US 3818748 A
A safety press apparatus for repeated operation at full production speed and for the prevention of injuries to an operator thereof. The apparatus comprises a traveling bolster assembly incorporated on a power press. The bolster assembly includes a bolster plate movable between an operative position beneath said press ram and a control and loading station spaced sufficiently from the ram of said press to prevent injury to any part of the operator. A safety control feature prevents operation of the press until the bolster is in its operative position and automatically returns the bolster to its inoperative position if its movement is obstructed. In one embodiment, the assembly includes restraining means for automatically restraining pressure pins used in conjunction with drawing dies except when the bolster is in its operative position.
Description (OCR text may contain errors)
United States Patent [191 June 25, 1974 Smit [ SAFETY APPARATUS FOR PRESSES [75.] Inventor: Henry Smit, Kentwood, Mich.  Assignee: Leslie E. Tassell, Grand Rapids,
Mich. a part interest  Filed: June 15, 1972  Appl. No.: 263,147
 US. Cl 72/448, 72/421, IOO/DIG. 18, 100/53  Int. Cl B2lj 13/00  Field of Search 72/448, 421, 351; 100/53, 100/DlG. 18
 References Cited UNITED STATES PATENTS 737,427 8/1903 Lemberg 100/208 2,908,405 l0/l959 Logan 214/] R 2,940,384 6/1960 Munschauer 100/214 2,988,234 6/1961 Barothy 214/1 R 3,002,479 l0/l961 Johansen .L 72/412 3,111,100 ll/l963 Georgeff 72/414 3,2l3,739 l0/l965 Zingone.... 83/563 3,225,686 12/1965 Clements. 100/43 3,273,490 9/1966 Beard... 100/229 3,455,141 7/1969 Bracco 72/446 3,673,849 7/1972 Voitsekhovsky 72/448 FOREIGN PATENTS OR APPLICATIONS 678,935 7/1939 Germany lOO/DlG. l8
Primary Examiner-Charles W. Lanham Assistant Examiner-Gene P. Crosby Attorney, Agent, or Firm-Price, Heneveld, Huizenga & Cooper  ABSTRACT part of the operator. A safety control feature prevents operation of the press until the bolster is in its operative position and automatically returns the bolster to its inoperative position if its movement is obstructed. In one embodiment, the assembly includes restraining means for automatically restraining pressure pins used in conjunction with drawing dies except when the bolster is in its operative position.
24 Claims, 13 Drawing Figures PATENTEDJUN25 I974 818,748
sum 3 HF 5 0 BOLSTER O CONTROL PANEL j 0 0 POWER ON BOLSTER I a 45/ ETURN /\48 SAFETY APPARATUS ron PRESSES This invention relates to safety apparatus for reciprocating type manually controlled presses, and more particularly, to a safety apparatus which includes a movable bolster assembly for the press apparatus, the bolster assembly being designed to prevent injury to an operator by keeping the operator at a safe distance from the moving press components and moving the bolster during production between the operator and reciprocal head of the press.
BACKGROUND OF THE INVENTION Manually controlled power presses with reciprocating heads are extremely old and well known. Such presses typically include a stationary bolster plate located underneath a reciprocatinghead with control means located immediately adjacent the bolster. The operator stands by the control means and feeds or loads the parts or articles to be processed onto the bolster and then actuates the motive power for the press by actuating the appropriate controls of the control means.
This type of power press has been found to be hazardous and dangerous to the operator in that he or she is required to reach under the head when loading and thus risk the possibility of the head coming down on his or her hands. Further, the close proximity of the operator to the working area of the press makes the possibilities of other injury to the operator extremely great.
Movable bolsters for use in conjunction with power presses are also well known in the press art. However, typically, the movable bolsters travel between a position outside of the press and a position within the press in order to effect die changes. Such bolsters have been designed. for infrequent, occasional usage in order to reduce th change-over time encountered during the retooling of the production facility to produce the different parts of the automobile. Thus, the prior bolsters have been slow-moving supports generally utilized only to facilitate the changing of dies and not for continuous and repeated production usage. As such, the previously known bolsters generally transport the entire die and cooperating or mating punch into the power press where the punch may be fastened to the upper movable ram of the press. After securing the punch, the material to be stamped or die-cut is placed on the lower portion of the die while the bolster remains in its stationary position within the power press. The press is then activated to punch, stamp or die-cut the material on the die after which the scrap and the punched article are removed. Thus, the bolster remains in one position during the production operation after transporting the die into the press and is not moved unless it is desired to change the die. Consequently, the bolster may remain in its stationary position within the power press for hours, days or even weeks during which time the production of one typeof part makes it unnecessary to move the bolster.
Other presses incorporating prior movable bolsters have not been designed with the complete safety of the operator in mind. In these other presses control and operation still may be effected from a position and in a manner which does not require operator location away from the press ram and/or use of both hands of the operator before the press operation may be initi-, ated.
- plete safety of those operating the press apparatus.
SUMMARY OF THE INVENTION In accordance with the present invention, I provide a press which has a control and loading station mounted at a remote position from the working area of the press so as to locate the operator a sufficient distance from the press to prevent any possibility of any extremity or part of the operator from passing into the working area. Further, I provide a bolster assembly including a movable bolster plate mounted on the press for movement between the control and loading station and the working area of the press, with means for moving the bolster back and forth between the working area and control station during productive operation of the press. Consequently, the operator is always located out of danger from having his or her extremities caught between the working components of the press.
Therefore, the object and feature of the present invention is to provide a movable bolster for use in conjunction with power presses in which the bolster assembly is integrated with the operation of the press apparatus and is arranged in order to prevent the injury of an operator of the combined apparatus.
It is another object and feature of the present invention to provide a traveling bolster assembly which includes apparatus which allows the bolster assembly to operate at production speeds and to be coupled with a power press apparatus for sustained, continuous, and repeated production usage.
It is a further object and feature of the present invention to provide a movable bolster assembly which may be coupled with a power press apparatus and includes means for controlling the operation of the entire apparatus in order to prevent the operation of the press unless the movable bolster is aligned with the ram or punch thereof, and which allows the press ram to be activated only from a single operating position located away from the press ram or punch.
It is yet another object and feature of the present invention to provide a traveling bolster assembly which automatically returns to a rest position away from the press or punch if it is prevented from being aligned with the ram or punch within a certain period of time by any type of a hindrance or obstacle.
It is a further object and feature of the present invention to provide a movable bolster assembly for use in conjunction with power press apparatuses which incorporate energy absorbing means adapted to allow high production speeds for the press and bolster combination.
It is an additional object and feature of the present invention to provide a movable bolster assembly for presses which incorporates integral pressure pins for use with drawing dies and which allows those pins to reciprocate only when the bolster assembly is aligned with the press ram or punch.
The above mentioned objects and features may be accomplished by providing a movable bolster assembly adapted for use in conjunction with a power press apparatus of the type including a frame, an upper movable ram, a lower press bed, and means for reciprocating the ram toward and away from the press bed. The
bolster assembly is adapted to support and transport the lower portion of a die-punch combination, i.e., a die and a die shoe, in repeated production operation. The assembly comprises in combination a traveling bolster movable between at least an inoperative position and an operative position; a pair of horizontally spaced parallel rails for supporting the bolster as it is moved between the first and second positions, a pneumatic fluid pressure cylinder for moving the bolster, energy absorbing means for decelerating the bolster from a predetermined speed within a predetermined distance at both the first and second positions, and control means for controlling the movement of the bolster between the said positions. The bolster assembly may also include a safety shield for shielding the internal mechanisms of the press and bolster from foreign objects which might otherwise be caught therein.
In the inoperative or loading position, the movable bolster is displaced from alignment with the ram of the press apparatus and is positioned adjacent a control and loading station wherein materials to be worked are positioned by an operator on the die supported by the bolster at a distance spaced from the working area of the press. In the operative position, the bolster is aligned with the ram of the press apparatus and the material is stamped, punched, cut or otherwise worked. The rail supporting the bolster between the first and second positions include recesses for vertically displacing the bolster such that it is supported by the press bed when it is aligned under the press rarn in the second position.
The control means for the operation of the combined bolster assembly and press apparatus is located adjacent the control and loading station so as to be activated only by an operator standing at such station. The control means prevents the operation of the power press apparatus at all times except when the bolster is in the operative position. The above structure assures the safe operation of the press apparatus as a whole and prevents injury to the operator thereof.
In another embodiment of the traveling bolster assembly, apparatus is included for preventing the reciprocation of at least one pressure pin which may be used in conjunction with a bolster supporting a drawing die. In this embodiment, the clamping mechanism allows the reciprocation of the pressure pins only in the operative position of the bolster when the bolster is aligned with the ram of the press apparatus, and otherwise causes the pressure pins to be moved in unison with the traveling bolster.
These and other objects, advantages and features of the invention will become apparent from a study of the following description taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the invention which comprises a safety press;
FIG. 2 is a fragmentary, plan view of the traveling bolster assembly of the safety press;
FIG. 3 is a cross-sectional side elevation of the traveling bolster assembly of FIG. 2 taken along lines III-III of FIG. 2;
FIG. 4 is a fragmentary, perspective view of the traveling bolster assembly of FIG. 2;
FIG. 5 is a fragmentary, cross-sectional view of a portion of the traveling bolster assembly taken along lines IVIV of FIG. 3;
FIG. 6 is a fragmentary, cross-sectional view of another portion of the traveling bolster assembly taken along lines V-V of FIG. 3;
FIG. 7 is a fragmentary, cross-sectional view of a portion of the bolster assembly control means operated by the main crankshaft of the power press taken along line VI-VI of FIG. 1:
FIG. 8 is a side elevation of the portion of the bolster assembly control means shown in FIG. 7;
FIG. 9 is a schematic electrical diagram of the electrical control circuit for the movable bolster assembly;
FIG. 9a is a limit switch setting diagram for indicating the closing and opening of limit switches in response to the position of the ram crank;
FIG. 10 is a front elevation of the press control panel;
FIG. 11 is a fragmentary, bottom view of another embodiment of the movable bolster assembly including a clamping apparatus for pressure pins used in conjunction with a drawing die; and
FIG. 12 is a fragmentary, cross-sectional view taken along line XII--XII of FIG. 11.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in greater detail to the drawings, FIG. 1 shows the safety press 12 which includes a movable or traveling bolster assembly 10. The bolster assembly 10 is designed for incorporation or integration generally with all types of power presses, including open back inclinable presses, such as that shown in FIG. 1, straight sided presses (not shown), presses utilizing air or partial revolution clutches (not shown) and presses utilizing dog-type or full cycle or revolution type clutches (not shown). Generally, the typical power press 12 (FIG. 1), with which the bolster assembly 10 is designed for use will include a frame 14, an upper movable ram or head 16, a lower press bed 18, and means 20 including main crankshaft 21 for reciprocating the ram 16 toward and away from the lower press bed 18. The bolster assembly 10 is adapted to be fitted or incorporated on the power press 12 in the working area generally between the lower press bed 18 and the upper movable ram 16. As will be explained in detail below, the movable or traveling bolster assembly 10 is designed to support and transport the lower portion of a punch-die combination, i.e. the die and die shoe 22 in FIG. 1, while the upper movable ram or head portion of the power press 12 carries the mating punch 24 which cooperates with the lower die. During use, the press 12 carries out an operation such as stamping, punching, die cutting or drawing a piece of material 26 to be worked. The material to be worked is generally a sheet material such as steel, aluminum or other metals. The apparatus is designed for operation from a control and loading station 28 located remote from the working area of the press, as shown in FIG. 1.
The movable bolster assembly 10 is constructed to support and transport a die into and out of alignment with the upper movable ram and punch in a manner which allows the sustained, continuous and repeated operation of the press in order to maintain full production operation and which insures the complete safety of the operator. As will be more fully described below, the
bolster assembly generally comprises a traveling bolster plate 30 movable between an inoperative position 31 (FIG. 1, phantom lines) and an operative position 32 (FIGS. 1, 2, and 3). In the inoperative position 31, the bolster plate 30 is horizontally displaced from alignment with the ram 16 and punch 24 and supports the die 22 in a position wherein the material to be worked 26 may be loaded on the die of the bolster 30 by an operator located at the control and loading station 28. In the operative position 32, the bolster plate 30 isaligned with the ram 16 and punch 24 and the material to be worked is punched or cut as described above by the operation of the press 12.
As shown in FIGS. 2, 3, and 4, movable bolster plate 30 comprises a rectangular plate 30 supported at its four corners on hearing means or wheels 33 and movable between inoperative position 31 and operative position 32 as shown in FIGS. 1 and 2. FIG. 2 shows only one-half of the traveling bolster assembly 10; the other or remaining half is an exact mirror image thereof. A bolster arm 37 is rigidly secured to the forward end 35 of the bolster 30'and provides a means for transferring the motive power of a power cylinder 61 to the bolster plate 30 for movement thereof.
The bolster plate wheels 33 ride a pair of horizontally spaced parallel elongated support rails 42 extending between the inoperative position 31 and the operative position 32. Wiper elements 41 (FIG. 6) are mounted on either end 35 and 36 of bolster 30 and remove all foreign objects from rails 42 as the bolster moves. The rails 42 include positioning means comprising recesses or depressions 52 within the supporting surfaces of the rails 42 corresponding to the positions of the wheels 33 when the bolster 30 is in the operative position 32. Thus, as the bolster 30 is moved toward the operative position 32, the wheels 33 will roll down into the recesses to vertically displace the entire bolster 30 downwardly onto the lower press bed 18 of the press 12. The bolster 30 will thus come to rest on bed 18 in an aligned position with the upper movable ram with its supporting wheels 33 spaced slightly above the bottom of the rail recesses 52. Consequently, the entire weight of the bolster 30 and any die and die shoe 22 supported thereon will be borne, by the lower press bed during the working operation of the power press 12. The force of the working operation will thus be relieved from the bearing means or wheels 33 by means of the depressions 52.
Power is supplied for the movement of the bolster 30 by a power means comprising the fluid motor pressure cylinders 61 mounted within the housings 45 (FIGS. 1, 5, and 6) which are arranged parallel to and extend along the length of the path of travel of the movable bolster 30. The housings 45 are covered by cover plates 47 partially broken away in FIG. 2. In the preferred embodiment, each cylinder 61 comprises a pneumatic cylinder having an internally mounted piston (not shown) and an extendable connecting rod or shaft 62 connecting the movable bolster 30 to the pneumatic cylinders 61 by means of the bolster arms 37. As shown in FIGS. 4 and 6, each bolster arm 37 has a cut-out portion 38 for allowing the passage therethrough of the elongated support rails 42 as the bolster is moved. Bolster arm 37 also includes a cut-out portion 39 receiving the end of the connecting rod 62. The end 62 is secured in cut-out 39 by bolt 63 as shown in FIG. 4.
The pneumatic cylinder 61 which is secured within the housing 45 by means of securing block 64 is adapted to move bolster 30 between the inoperative position 31 and an operative position 32. Also mounted within housing 45 are the energy-absorbing means comprising two shock absorbers 82 and 84 mounted at each end of the path of travel of the bolster 30. Shock absorber 82 is mounted on the end wall 46 of housing 45 and includes a compressible spring arm 86 which is contacted and compressed by the first side 43 of the bolster arm 37 as the bolster 30 moves toward and into its inoperative position. Similarly, shock absorber 84 is mounted on mounting block 83 which in turn is secured to cover 47 of housing 45. Shock absorber 84 includes compressible spring arm 88 which is contacted and compressed by the opposite side 44 of bolster arm 37 as the bolster plate 30 is moved toward and into the operative position 32. Additionally, positive stops or abutment blocks 90 and 92 (FIGS. 2 and 3) are provided for stopping the travel of the movable bolster 30 in case of failure by the shock absorbers 82 and 84. The shock absorbing or energy absorbing means 80 thus provides a means for quickly decelerating the movable bolster 30 from its controlled production speed to a complete stop within a predetermined distance as determined by the resistance of the compressible spring arms included in the shock absorbers. If desired, the shock absorbers may be adjustable in order to accomodate various weights and sizes of dies 22 to be supported and transported by the movable bolster 30. Accordingly, if the size of the die supported by the bolster plate 30 is increased, the shock absorbers are adjusted in order to increase the amount of force needed to compress the spring armsthereon. Thus, the increased mass of the larger combined die and movable bolster plate will be brought to a complete stop within the same distance as with a lighter and smaller die as described above.
The bolster assembly 10 preferably further includes additional safety features designed to prevent injury to an operator thereof. One of these features is the retractable cover means shown in FIGS. 1 through 3. Retractable cover means 100 include two retracting rollers 102 and 104 mounted adjacent the extreme ends of the path of travel of traveling bolster 30, i.e., in the first and second positions 31 and 32 respectively. Rolled on the rollers 102 and 104 are durable, flexible covers 106 and 108 respectively, which are formed from any suitable material. The flexible covers 106 and 108 are fixedly secured to the first and second ends 35 and 36 of the traveling bolster 30 by means of securing bars 110 and 112. Rollers 102 and 104 are spring biased to rollably retract the flexible covers as the bolster travels toward and away from the respective rollers. Thus, as the bolster 30 travels from its inoperative position 31 to its operative position 32, cover 106 will be pulled from roller 102 by bolster end 35 and simultaneously cover 108 will be rollably retracted on roller 104 as the bolster moves toward position 32. Similarly, as the bolster 30 travels back toward its inoperative position 31, cover 106 will be rollably retracted and cover 108 will be extended. Covers 106 and 108 thus cover what would otherwise be open areas exposing the internal mechanisms of both the bolster assembly 10 and the power press 12 if the covers were not provided. The covers thus prevent foreign objects such as tools and other loose matter from falling into the internal mechanisms and preventing those mechanisms from either jamming or throwing the foreign objects in a manner which might injure the operator of the apparatus. As will be appreciated by one skilled in the art, stationary trays may be fitted beneath the area in which the bolster 30 travels back and forth, which trays provide the same function of preventing foreign objects from entering the internal mechanisms of the bolster assembly and press 12, but which are not retracted and extended in a manner similar to the covers 106 and 108.
A second safety feature which preferably is incorporated on the traveling bolster assembly 10 is a safety shielding means 115 as shown in FIGS. 1 through 3. Safety shielding means 115 comprises a protective plate or shield 117 mounted generally vertically on a generally horizontal support rod 119 (FIG. 3) removably mounted atop the extending ends of the housings 45 and retained thereon by restraining means 121. Restraining means 121 comprises mounting blocks which include spring-biased means 123 which prevent the escape of the support rod 119 unless a force of a predetermined size is exerted upon either the plate 117 or rod 119.
Should a tool, piece of metal or other foreign object become lodged between the first edge 35 of bolster 30 and the safety shielding means 115, and be thrown by the first edge 35 toward the operator standing behind the shield 117, the safety shield will block the motion of the foreign object and prevent the object from striking and injuring the operator standing therebehind. Should the foreign object be impelled with a force sufficiently great to overcome the resilient holding force of the spring-biased means 123, the compression of the spring and the movement of the rod 119 will expend the energy of the moving foreign object and reduce its force such that, even if the safety shield is knocked against the operator standing therebehind, the force of the impact will be insufficient to injure him. A flexible connecting means such as a chain (not shown) may be secured between the mounting blocks 121 and the safety shield 117 or support rod 119 to prevent the movement of the safety shield beyond a predetermined distance.
Thus, the safety shielding means provides an additional safety means mounted beyond the end 35 of bolster 30 and immediately in front of the operating position 28 which is the only position in which an operator of the combined power press 12 and traveling bolster assembly 10 can stand in order to reach the control panel 132 and load the work piece on the die 22.
Referring now to FIG. 9, the control means for controlling the operation of the traveling bolster assembly 10 and its coordination with the operation of the power press 12 will be described in greater detail. The control means basically comprises a solenoid-operated fluidflow control valve system (not shown) and an electrical circuit for controlling the operation of the control valve system. The control valve system is of the type which is well known in the art and includes solenoid responsive fluid valving for actuating the pneumatic cylinders 61 as described above. Fluid valving is also included to operate a registry means for indicating the exact positioning of the movable bolster 30 in its operative position 32.
As shown in FIG. 9, the electrical control circuit comprises a means for operating the traveling bolster assembly 10 in an automatic or semi-automatic sequence of operations as desired. The electrical circuit includes the bolster advance control solenoid 160 and the bolster return control solenoid 238 which control the operation of the pneumatic cylinder 61 for advancing the bolster under the ram of the press and for returning it back to the control and loading station.
The safety press including the traveling bolster 30 may be operated in one of three different operational modes, e.g., the set-up mode I, the bolster travelingpress run mode 11, and a bolster-stationary-press run mode 111. These modes are determined by the setting of the selector switch 150 (FIG. 10) which is a wafer-type switch having a plurality of switch parts or contact groupings, 150a, 150b, 150e, 150d, 150e, and 150f, all as disclosed in FIG. 9. It will be noted in the various positions I, 11, and III, the parts or groupings 150a, 150b, etc., of the switch 150 are connected or disconnected to the electrical control circuit so as to control the energization and de-energization of the advance solenoid 160 and the return solenoid 238.
In order to undersatnd this circuit and its operation, the Mode 11 operation in which the bolster is automatically advanced under the ram, the ram is actuated and then the bolster is returned to the control and loading station, will be explained.
Referring to advance control solenoid 160, it will be noted that it is a part of circuit 210 which is also comprised of the limit switch LS-7 and the relay contacts lCR-l, the entire circuit 210 being connected to the line 201 in which is located the main power switch 144, the stationary contacts a and 138a of the palm switches 138 and 140, and the switch b. Thus, when the selector switch 150 is adjusted to mode 11, power is supplied to the line 201 through switch part 15% from the line 202 which is connected to the press power supply. Thus, closing of the contacts 138a and 140a by the actuation of the palm switches 138 and 140 energizes the bolster advance control solenoid which immediately sets the fluid control valve in a position to cause the cylinder 61 to start advancing the bolster toward the ram, it being understood that LS-7 is closed at the inoperative position of the bolster and opens as the bolster advances but without effecting the position of the fluid control valves. When the bolster reaches the proper position under the ram, limit switch LS-S is acmated by plate 152 mounted on bolster arm 37 as shown in FIGS. 2, 3, and 5, thereby closing the circuit 203 and energizing the pin extension control solenoid 196. This immediately extends the register pins 200 (FIGS. 2, 3, 4, and 5) into the openings 202 of the bolster by means of the pneumatic cylinders including pistons 172 (FIG. 5). Extending the register pins into the bolster closes limit switches LS-l and LS2 by means of plates 154 mounted on the rear extensions of pins 200 (FIGS. 2, 3, and 5). Switches LS-l and LS-2 are located in line 204 which is connected between the limit switches LS-S and LS-9 and to the press clutch control (not shown). The press clutch control is operated by closing circuit 204 only after the press control circuit is reset by the closing of line 213. This resetting is accomplished in Modes 1 and II by the closing of limit switch LS-7 each time the bolster returns to inoperative position. Operation of the press clutch control by depressing the palm switches 138 and 140 causes the ram to be actuated downwardly to perform its working operation in the work piece located in the bolster.
As shown in the limit switch settings (FIG. 9a) for the crank limit switches LS-9 and LS-l4, immediately before the crank and the ram reach the top position, that is, between approximately 345 and 358, limit switch LS-9 is actuated thereby opening circuit 203 of the pin extension control solenoid 196 and at the same time closing switch LS-9 located in line 205. This closes the circuit of line 205 since the switch part 150d is on Mode 11 and immediately energizespin retraction control solenoid 230 causing retraction of the register pins out of the bolster. The retraction of the register pins causes plates 154 to contact and close limit switches LS- and LS-l 1(FIG. 2) located in line 206 which energizes the relay coils lCR and lTD. Energization of lCR opens the circuit through the bolster advance control solenoid 160 by means of contacts lCR-1 and closes relay contacts lCR-2 in line 207. Energization of the time delay relay coil lTD closes the switch lTD-l thus completing the circuit of line 207 and energizing the return control solenoid 238. This immediately changes the position of the control valve for cylinder 61 causing the cylinder 61 to return the bolster to the control and loading station. After a time controlled by the timer relay coil lTD, the switch lTD-l opens leaving the bolster and the entire circuit in its original position ready to be actuated by the palm switches.
The entire operation of Mode II can also be initiated by stepping on the foot pedal 142 thus providing power to line 201 from the press through the switch part 150c of the selector switch 150.
Preferably, in Mode II, it is desirable that the bolster is moved at high speed. Therefore, I provide a highspeed control solenoid 265 located in the line 208 in series with switch part 1506*. This high-speed control solenoid by appropriate valving causes the rate at which the air is fed to the cylinder 61 to be increased, thus increasing the speed at which the cylinder 61 actuates the bolster. If high-speed solenoid 265 burns out or in any way becomes non-functional or de-energized, the bolster is accordingly controlled to move at low speed.
Having described the operation of Mode II, the operation of Mode I is easily understood. In accordance with Mode I, the bolster can be advanced manually by operation of the palm switches 138 and 140 and then only when the bolster is in proper position, the press ram can be actuated intermittently without causing the bolster to retract, thereby allowing the proper positioning of dies and work pieces when changed or used for the first time.
In operating under Mode l, the selector switch 150 is adjusted to the Mode 1 position. In this position, the only part of the selector switch 150 that provides an electrical connection is part 1500 located in the line 209 which in turn is connected to the line 201 on the power side of contacts 138a and 140a. Thus, it will be evident that actuation of palm switches 138 and 140 closes contacts 138a and 140a completing the circuit from the power supply through line 209, 201, and 210 so as to energize the bolster advance control solenoid 160. When the bolster reaches its operative position under the ram, LS-S is closed permitting pin extension control solenoid 196 to be energized by depressing palm switches 138 and 140. As previously described, this closes the circuit through line 204 by closing the limit switches LS-l and LS-2 causing the ram to be actuated. Intermittent operation of the arm is possible by intermittent depression of palm switches 138 and 140 during the stroke of the arm. As the ram returns to its top position passing through 345 as shown in FIG. 9a, limit switch LS-9 opens and LS-9 closes as previously described in relation to Mode II. However, the switch part d projibits energization of the pin retraction control solenoid 230. As a result, there is no automatic return of the bolster as previously described in relation to mode II, and the safety press apparatus operation comes to a standstill with the ram at the top and the bolster underneath the ram. However, limit switch 14 located in the line 211 is closed and this closes the circuit through the indicator light A which designates that the ram is at its top position. Connected to line 211 is the line 213 having a manual bolster retract switch 148 which, when closed, energizes the pin retraction control solenoid 230 causing the pins to be retracted and limit switches LS-10 and LS-ll to be closed. As previously described, the closing of LS-10 and LS-ll energizes coils ITD and lCR and thus causes the closing of the circuit of line 207. This energizes the return control solenoid 238 causing the cylinder 61 to be actuated for returning the bolster to its inoperative position at the control and loading station. Manual retract switch 148 may be used any time when LS-14 is closed, i.e., until approximately 10 after crank 21 of press 12 passes its top position as shown on FIG. 9a. Bolster 30 can also be returned to the loading station by manually switching selector switch 150 from Mode I to Mode II on panel 132.
The third operational mode with the bolster stationarypress run Mode III may be selected on selector switch 150. In Mode III, the traveling bolster 30 remains stationary in its operative position underneath the ram while the movable ram is automatically actuated for continuous and repeated work cycles by means of the press control circuit. Normally, Mode III is selected after the bolster has been advanced to its operative position using Mode I. Thus, the continuous operation of the press ram is generally selected only after the die location has been verified using set of Mode I. How ever, the sequential operation of advancing the bolster under the ram in Mode III is also the same as in Mode I, that is, after the bolster reaches a proper position and the register pins are extended into the bolster, the pins and bolster cannot be retracted because switch 150d in line 205 is open, thus preventing the limit switch LS-9' from closing the circuits to energize the pin retraction control solenoid. However, in Mode III, as opposed to Mode l, the closing of the switch part 15% permits the circuit through line 202, 201, and 2043 to be closed for continuous actuation of the press ram as described above.
It should be understood that in order for the press ram to be actuated, the press control circuit must be reset by closing the circuit through the line 213. This is accomplished in one of two ways. As previously described, one way is as the bolster returns to the inoperative position, LS-7" closes which resets the press control circuit. In Mode II, line 213 is always closed by switch part 150f and therefore the press control circuit is reset after each operation of the ram. As a result, in Mode III the press ram is continuously actuated without returning the bolster to the operator. It is possible also to provide a means in the press control circuit which will cause the ram to operate in single cycles without the bolster returning by means of the repeated actuation of the palm and foot switches.
One safety feature that is present in all the modes, I, II, and Ill, involves the bolster delay circuit which is found in line 214. This circuit includes the limit switches LS-7' and LS-S' and the time delay relay coil 2TD. Thus, as the bolster is being advanced toward the ram of the press, if the bolster does not reach its operative position within a predetermined time as set by the coil 2TD, the circuit through line 207 will be closed by the closing of the switch 2TD to energize the return control solenoid 238 which automatically returns the bolster to the control and loading station. If the bolster reaches the operative position within the said time limit, limit LS-S' opens preventing the energization of coil 2TD. Further, an emergency stop switch 146 is included to out all power to the entire safety press apparatus when desired in emergency situations.
DESCRIPTION OF ALTERNATIVE EMBODIMENT A second embodiment of the traveling bolster plate may be incorporated in the bolster assembly 10 for use with power presses utilizing drawing dies wherein pressure pins are incorporated with the drawing die and cooperate with the upper movable ram of the power press to capture and retain a piece of material to be worked prior to its drawing or forming over a portion of the drawing die. Such pressure pins are commonly used in the press art and are normally utilized in conjunction with a pressure pin buffer means such as an air cushion pad which damps and resists the movement of the pressure pins in order to properly clamp the material to be worked between a draw ring mounted on the end of the pressure pins and the upper movable ram or punch. As will be appreciated, the incorporation of at traveling bolster plate in a power press of the type described above, utilizing a drawing die, would nonnally be impossible using existing designs since the pressure pins extend through the normal location of the bolster plate beneath the upper movable ram. Accordingly, the pressure pins would prevent the movement of the bolster plate unless additional means are incorporated to allow the movement thereof. The additional or alternative embodiment of the traveling bolster plate described hereinafter incorporated an apparatus conceived in recognition of and as a solution for this problem.
As shown in FIGS. 11 and 12, the alternative embodiment of the traveling bolster comprises a movable bolster 300 for supporting a drawing die 302 typically of the type shown in FIG. 12. The drawing die has an upper portion comprising a punch or ram 304 mounted on the upper movable ram 16 of a typical power press 12, as shown in FIG. 1 and a lower drawing die portion or drawing post 306 secured or fastened in place on the movable bolster 300. At least one and usually a plurality of pressure pins 310 are reciprocally mounted in apertures 312 formed in the bolster 300. Apertures 312 extend all the way through bolster 300 and are formed such that they are perpendicular to the supporting surface 314 of the bolster 300. Pins 310 support a draw I ster 300 operates between its operative and inoperative positions in a manner similar to that described above for the first embodiment of the movable bolster 30, a piece of material to be worked 308 will be positioned over draw post 306 in contact with draw ring 309 mounted on the upper ends of the pressure pins 310 when the bolster is in its inoperative position, as shown in the left-hand portion of FIG. 12. The bolster will then move to its second position where the punch 304 will be lowered such that the material 308 is clamped between the punch 304 and the draw ring 309. As the punch continues downwardly, the punch 304 will force the material 308 downwardly over the draw post 306 thereby drawing the material 308 into the desired shape. At the same time, the pressure pins 310 will be reciprocated downwardly against the resistance of the buffer means or air cushion pad 316 thereby securely maintaining the clamping of the material 308 during the drawing operation.
FIGS. 11 and 12 also show the present novel inventive apparatus designed to carry the pressure pins 310 during all movements of the traveling bolster 300 and to allow the reciprocation of those pins 310 only when the bolster 300 is in its operative position. As depicted therein, a clamping means 320 is provided in the bottom surface of the movable bolster 300 in order to perform the above-described function. Clamping means 320 comprises a slidable plate member 322 mounted flush with the bottom surface 318 of the bolster 300 in a recess 324. The plate member 322 is held in place by two bar members 326 which are also flush with bottom surface 318 and extend along the length of the recess 324 provided for the plate member. Slots 328 are provided in the plate member 322 having different size ends 330 and 332 to alternately allow the reciprocation of the pressure pins 310 therethrough and to retain or clamp the pressure pin 310 in a raised position. The larger end 330 of slot 328 is formed to be slightly larger than the outside diameter of the main portion 311 of the pressure pins 310 in order to allow the sliding reciprocation of the pressure pins 310 therethrough. The smaller end 332 of the slot 328 is formed to be slightly larger than a reduced diameter portion 313 of the lower end of the pressure pins 310. The main portion 311 of the pressure pins is separated from the reduced diameter portion 313 thereof by a shoulder 315. Accordingly, when the pins 310 are in the raised position as shown in the left portion of FIG. 12, Le, when the bolster 300 is traveling between the inoperative and operative positions, the pins are captured and retained in the raised position by means of the smaller ends 332 of slots 328. However, when the bolster 300 is in the operative position, the larger ends 330 of slots 328 are aligned with apertures 312 in bolster 300, and the pins 310 are allowed to reciprocate against the resistance of air cushion pads 316 by means of the force imposed by the ram or punch 304.
Shifting or release means 334 are included to shift the sliding plate member 332 between the appropriate positions in order to allow the pressure pins 310 to reciprocate at the desired times. Shifting means 334 include biasing means such as springs 336 at one end of the sliding plate and block means such as stop blocks 338 at the opposite end of the sliding plate for correctly positioning the slidable plate member 322 at the proper time. Thus, as shown in FIG. 11, in the left-hand portion thereof, the bolster 300 is traveling toward the opl3 erative position where it will be aligned with the upper movable ram 16 of power press 12. During such travel, the,springs 336 continuously bias the plate member 322 toward its first clamping position wherein the smaller ends 332 of slots 328 engage shoulders 315 of the pins 310 thereby retaining those pins in their raised positions and causing them to move in unison with the traveling bolster 300. However, when the traveling bol' ster 300 reaches the second position beneath the upper movable ram, as shown in the righthand portion of FIG. 11, the slidable plate member 322 is engaged by stop blocks 338 which are fixedly positioned in the second operative position of traveling bolster 300 on a portion of the power press 12. Consequently, stop blocks 338 contact one end of the slidable plate member 322 and force it against the biasing force of springs 336 and moving plate member 322 into its second or release position wherein the larger end 330 of slots 328 are aligned with the apertures 312 of bolster 300. Therefore,ithe bolster 300 and slidable plate member 322 will each be positioned in their respective second positions at the same time wherein the apertures 312 and larger ends 330 of slots 328 are aligned thereby allowing the reciprocation of pressure pins 310.
Accordingly, the additional embodiment of traveling bolster 300 incorporating the slidable plate member 322 allows the traveling bolster assembly to be incorporated on power presses of the type utilizing pressure pins and bumper means such as air cushion pads as described above. It will be understood that the clamping means including the slidable plate member 322 is automatically shifted between its two positions to allow the reciprocation of the pressure pins only when the traveling bolster 300 is in its second operative position beneath the upper movable ram 16, and at all other times, the clamping means 320 secure and capture the pressure pins in a raised position thereby allowing the unhindered movement of the traveling bolster 300.
As will now be apparent, the safety press apparatus including traveling bolster assembly 10 incorporated on a power press 12 provides significant safety advantages to an operator of the combined apparatus while maintaining the full production speeds and efficiencies required in modern day industrial applications. The assembly 10 may be incorporated on various types of presses including open back inclinable presses, straight-sided presses and presses utilizing various types of clutch mechanisms. Additionally, the assembly 10 may be incorporated for use on presses using drawing dies in which pressure pins must be carried with the traveling bolster at all times except when the bolster is positioned to be in alignment with the upper movable ram of the power press. Finally, it will be seen that the traveling bolster assembly 10 incorporates the use of pneumatic power means which enable the high production speeds required to maintain production standards. However, other fluid motive means may be utilized without deviating from the spirit of the invention.
While several forms of the invention have been shown and described, other forms will now be apparent to those skilled in the art. Therefore, it will be understood that the embodiments shown in the drawings and described above are merely for illustrative purposes, and are not intended to limit the scope of the invention which is defined by the claims which follow.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. In a power press of the type having an upper movable ram and a lower press bed; means for reciprocating said ram toward and away from said bed; a bolster assembly for supporting a die on said bed beneath said ram; control means for controlling the operation of said ram, said control means including a manually actuated means; said press permitting an operator standing adjacent thereto to place work pieces on said die and operate said manually actuated control means; the improvement comprising:
means for mounting said manually actuated means at a first position located a distance spaced horizontally from said ram whereby an operator standing in a position to actuate said manually actuated means cannot reach under said ram; means for movably supporting said bolster for movement from an operative position underneath said ram to a remote position adjacent said manually actuated means where the operator stands to operate said manually actuated means and vice versa;
motive power means for moving said bolster between said positions; and
additional control means for controlling the said motive power means whereby an operator standing at said manually actuated means remote from said ram can first place work pieces on said die and then actuate said manually actuated means for operation of said control means and additional control means to cause said die and work piece to move under said ram and said ram to perform a working operation on said work piece.
2. The apparatus of claim 1 which further includes safety shielding means for shielding an operator from foreign objects accidentally impelled by said bolster.
3. The apparatus of claim 2 wherein said safety shielding means comprises a protective plate secured to a support rod, said plate and rod being mounted on said assembly between said remote position and said operator position; said rod being removably secured on said assembly by a spring-biased means which releases said rod and plate only when a force greater than a predetermined level is exerted on said plate.
4. The apparatus of claim 1 which further includes cover means for shielding the internal mechanisms of said press and bolster from foreign objects.
5. The apparatus of claim 4 wherein said cover means comprise retractable curtains and said bolster has opposite ends facing said operative and remote positions respectively, said curtains fixed to said opposite ends of said bolster and mounted on retracting rollers adjacent each of said positions such that, as said bolster is moved between said remote and operative positions, said curtains are alternately extended and retracted to cover the areas between those positions and said bolster.
6. The apparatus of claim 1 wherein said apparatus includes support rails for said bolster; said bolster including a plurality of wheels for movement along said rails; said rails including positioning means comprising recesses formed below the normal supporting surface of said rail means in said operative position; said recesses having a bottom and end portions; said end portions being inclined between said normal supporting surface and said bottom portion such that said wheels are received in said recesses by rolling along said inclined end portions whereby said bolster is lowered onto and supported by said press bed.
7. The apparatus of claim 1 wherein said motive power means comprises at least one fluid pressure cylinder including an extendable piston and piston rod; said piston and piston rod being extended in response to said control means in order to move said bolster between said remote and operative positions.
8. The apparatus of claim 7 wherein said fluid pressure cylinder comprises a pneumatic cylinder, said piston and piston rod being extended with compressed air.
9. A power press apparatus in accordance with claim 1 wherein said control means comprises circuit means and selection means for selective operation of said circuit means; said circuit means arranged to be activated only by an operator actuating said manually actuated means while standing at said operator position; said selection means comprising:
first means for selecting coordinated low speed operation of both said bolster and press ram;
second means for selecting coordinated high speed operation of both said bolster and said press ram; and
third means for selecting the press ram operation alone when said bolster is in said operative position; said circuit means adapted to cause the movement of said bolster from said remote position to said operative position in a predetermined period of time; said circuit means also adapted to prevent further operation of said apparatus if said movement of said bolster in obstructed.
10. The apparatus of claim 9 wherein said circuit means comprises fluid flow control valve means and electrical means for controlling said valve means; said electrical means and valve means adapted to cause said bolster movement between said remote and operative positions within said time period; said electrical means adapted to cause the automatic return of said bolster to said remote position when said bolster does not reach said operative position within said time period.
11. The apparatus of claim 9 wherein said control means further includes registry means for indicating the correct positioning of said bolster in said operative position and means cooperating with said registry means for activating the reciprocation of said ram in response to said indication of said correct position.
12. The apparatus of claim 11 wherein said registry means includes at least one extendable pin, fluid pressure means for extending said pin, at least one electrical limit switch for controlling the activation of said fluid pressure means; said cooperating means comprising a plate mounted on said pin for engaging at least one electrical limit switch.
13. The apparatus of claim 1 including energy absorbing means comprising at least one shock absorber mounted at said remote position and at least one shock absorber mounted at said operative position, said shock absorbers arranged such that they decelerate said bolster at said respective positions.
14. The apparatus of claim 13 wherein said shock absorbers are adjustable in order to accommodate various dies having various masses which are supported and transported by said bolster.
15. A traveling bolster assembly for a power press including a press ram; said assembly adapted to prevent injuries to operators of such presses during the repeated production usage of such presses; said assembly comprising in combination a movable bolster means; support means for said bolster means; fluid cylinders on either side of said bolster means for moving said bolster means between at least a first and second positions; control means for controlled movement of said bolster means between said positions; deceleration means for said bolster means at said respective positions; said support means including bearing means for anti-friction movable support of said bolster means and means for removing any support forces from said bearing means when said bolster means is in said second position; manual means for actuating said control means spaced a distance from the press ram whereby an operator of said assembly on a press cannot reach under said ram; and means on either side of said bolster means for housing said cylinders, at least a portion of said control means, and said deceleration means.
16. A traveling bolster assembly as described in claim 15 wherein said bolster means comprises a bolster plate for supporting a die; said plate including a plurality of supporting wheels comprising said bearing means; said support means including a pair of elongated rails spaced horizontally apart and parallel to one another; said means for removing any support forces from said bearing means including depressions formed in said rails at said second position such that, in said second position, said wheels are received in said depressions, thereby vertically displacing said bolster plate and causing said bolster plate to be supported by a portion of a press operated in conjunction with said assembly.
17. A traveling bolster assembly for a power press including a press ram; said assembly adapted to prevent injuries to operators of such presses during the repeated production usage of such presses; said assembly comprising in combination a movable bolster means; support means for said bolster means; motive power for moving said bolster means between at least a first and second positions; control means for controlled movement of said bolster means between said positions; and deceleration means for said bolster means at said respective positions; said control means including:
fluid flow control valve means;
electrical means for controlling said valve means;
said electrical means including timing means; and
selection means for selective operation of said electrical means; said electrical means and fluid flow control valve means adapted to cause the movement of said bolster means from said first position to said second position within a predetermined time period set on said timing means; said electrical means and fluid flow control valve adapted to cause the automatic return of said bolster means to said first position when said bolster does not reach said second position within said period.
18. A traveling bolster assembly as described in claim 17 wherein said control means further includes registry means for indicating the correct positioning of said bolster plate in said second position and cooperating means for activating a subsequent operation of a press used in conjunction with said assembly.
19. A traveling bolster assembly for a power press including a press ram; said assembly adapted to prevent injuries to operators of such presses during the repeated production usage of such presses; said assembly comprising in combinationa movable bolster means;
support means for said bolster means; motive power means for moving said bolster means between at least a first and second positions; control means for controlled movement of said bolster means between said positions; and deceleration means for said bolster means at said. respective positions; said deceleration means including at least one shock absorber mounted in each of said first and second positions, said shock absorbers adapted to stop said bolster means in said respective positions in a certain distance from a predetermined speed.
20. A traveling bolster assembly for a power press including a press ram; said assembly adapted to prevent injuries to operators of such presses during the repeated production usage of such presses; said assembly comprising in combination a movable bolster means; support means for said bolster means; motive power means for moving said bolster means between at least a first and second positions; control means for cntrolled movement of said bolster means between said positions; and deceleration means for said bolster means at said respective positions; said assembly further including a releasable safety shield maintained in a springbiased mounting immediately adjacent one of said positions of said bolster means.
21. A traveling bolster assembly as described in claim wherein said assembly further includes a retractable cover curtain, said curtain mounted on spring-biased rollers and secured to the opposite ends of said bolster means adjacent said first and second positions such that said curtain alternately covers the areas between said bolster means and said respective positions as said bolster means is moved.
22. A movable bolster assembly for mounting on a power press including at least two fluid cylinders for moving said bolster between at least two horizontal positions with respect to said power press; said fluid cylinders being mounted at positions spaced laterally of the opposite lateral sides of said bolster means; press control means for preventing operation of the press in all positions except one of said horizontal positions of said bolster; energy absorbing means for repeatedly stopping said bolster in said respective positions from a high rate of speed such that the overall production speed of said bolster and press is maintained; and means defining housings for said cylinders, said housing means also including said energy absorbing means and a portion of said control means.
23. A movable bolster as described in claim 22 wherein said energy absorbing means comprise at least one shock absorber mounted adjacent each of said positions such that a portion of said bolster is contacted, thereby stopping the entire bolster in said positions with said shock absorbers.
24. A traveling bolster assembly for a power press; said assembly adapted to prevent injuries to operators of such presses during the repeated production usage of such presses; said assembly comprising in combination a movable bolster means; support means for said bolster means; motive power means for moving said bolster means between at least a first and second positions; control means for controlled movement of said bolster means between said positions; and deceleration means for said bolster means at said respective positions; said control means including means for actuating said motive power means to cause the movement of said bolster means between said first and second positions in a predetermined period of time, and means for preventing further operation of said assembly and any associated power press if said movement of said bolster means between said positions is not completed in said predetermined period.
UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 ,8l8,748
DATED June 25 1974 lN\/ ENTOR(S) Henry Smit It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
On the cover page of the patent, in the list of United States patent references cited;
The following should be added:
"3,446,106 5/1969 Ferris at al 83/400 Column 15, line 32;
"in" should be --is- Signed and Scaled this twenty-eight Day of October 1975 [SEAL] Attest:
RUTH C. MASON C. MARSHALL DANN Atrestmg Officer Commissioner nj'Parents and Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 ,8l8,748
DATED June 25 1974 lN\/ ENTOR(S) Henry Smit It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
On the cover page of the patent, in the list of United States patent references cited;
The following should be added:
"3,446,106 5/1969 Ferris at al 83/400 Column 15, line 32;
"in" should be --is- Signed and Scaled this twenty-eight Day of October 1975 [SEAL] Attest:
RUTH C. MASON C. MARSHALL DANN Atrestmg Officer Commissioner nj'Parents and Trademarks