US 3771930 A
A hydraulic metallic powder press including a press cylinder and a piston displaceable in the press cylinder. A piston rod is connected to the piston and a seal positioned adjacent the piston rod and at a location where the piston is led out of the press cylinder. A free end of the rod bears a die and is adapted to be introduced into a cavity for compacting metallic powder contained therein. An adjustable sleeve is provided in the press cylinder inwardly of the seal. The sleeve at least partially encloses the piston rod and has an external thread and the press cylinder has an internal thread in mating relationship with the sleeve thread. The sleeve further has a slide. A rotatable gland at least partially encloses the sleeve and has a longitudinal groove therein for guiding the slide. The groove runs in the axial direction of the piston rod and a drive motor is operatively coupled for rotatably moving the gland. Accordingly, the length of the stroke of the die into the cavity is thereby limited.
Description (OCR text may contain errors)
United States Patent Ginzel et al.
1 Nov. 13, 1973 1 HYDRAULIC PRESS FOR COMPACTING METAL POWDER  lnventors: Severin Ginzel; Peter Niederhuber,
both of Munich, Germany  Assignee: W. Bussmann KG, Munich, 1 Germany  Filed: Aug. 8, 1972 1 ppl 032 8178 i N  Foreign Application Priority Data Apr. 24, 1969 Germany P Related U.S. Application Data  Continuation-impart of Ser. No. 28,341, April 14,
 U.S. Cl 425/78, 92/l3.1, 100/256, 100/257, 72/441  Int. Cl B221 3/04  Field of Search 425/78, 151, 363; 72/441, 453; 100/256, 257; 92/131  References Cited UNITED STATES PATENTS 2,648,096 8/1953 Baigent 92/l3.l X 2,762,078 9/1956 3,044,138 7/1962 3,080,852 3/1963 3,191,232 6/1965 Haller 425/7 Primary Examiner-Robert L. Spicer, Jr. Att0rney.lim W. Gipple et a1.
 ABSTRACT A hydraulic metallic powder press including a press cylinder and a piston displaceable in the press cylinder. A piston rod is connected to the piston and a seal positioned adjacent the piston rod and at a location where the piston is led out of the press cylinder. A free end of the rod bears a die and is adapted to be introduced into a cavity for compacting metallic powder contained therein. An adjustable sleeve is provided in the press cylinder inwardly of the seal. The sleeve at least partially encloses the piston rod and has an external thread and the press cylinder has an internal thread in mating relationship with the sleeve thread. The sleeve further has a slide. A rotatable gland at least partially encloses the sleeve and has a longitudi' nal groove therein for guiding the slide. The groove runs in the axial direction of the piston rod and a drive motor is operatively coupled for rotatably moving the gland. Accordingly, the length of the stroke of the die into the cavity is thereby limited.
5 Claims, 3 Drawing Figures EESERW/R PATENTEUNHYIIJIQIS I 377L930 sum 1 or 3 Fig.1
FESER V011? PATENTEUNBY 1a 1925 3771, 930
SHEET 2 0F 3 v HYDRAULIC PRESS FOR COMPACTING METAL POWDER RELATED U.S. APPLICATION This is a continuation-in-part application of Ser. No. 28,341, now abandoned filed Apr. 14, 1970 by Severin Ginzel et al. for Hydraulic Press for Compacting Metal Powder.
The present invention is concerned with a hydraulic metal powder press in which a press cylinder has been placed within a machine frame. In the press cylinder, a piston on which a pressure medium acts is guided in such a way that it can be moved to and fro. The piston has a piston rod which leads tightly out of the cylinder, and the free end of which supports a pressing table or pressing plate, to which a press die has been attached. The press die is shaped in accordance with the form of the pressing to be manufactured and is introduced into a shaping cavity of a pressing tool which is filled with metal powder, when the piston rod is extended, so that the metal powder will be compacted to a pressing, under high pressure.
The precision of the dimensions of pressings manufactured in this way depends on how precisely the stroke of the piston supporting the press die can be circumscribed during the pressing process. In a known hydraulic metal powder press, the height of lift is circumscribed by adjustable stops that are arranged within the machine frame. The stops have been mounted on supporting columns and their position can be adjusted very finely by way of worn gears. But, this has the disadvantage that dust, in particular metal dust, collects on the stops, whereby the precision of the stroke limitation of the piston will suffer, unless the stops are carefully kept clean at all times.
A sheet-metal press is also known, in which the stroke limitation of the piston is achieved by means of stop rings which lie within the press cylinder, and which can be screwed, from the outside, into the press cylinder far (Swedish Pat. No. 204,205). The adjustment of those stop rings takes place by means of a snail and of a worm gear that is joined rigidly with the stop rings. In order to maintain the snail and worm gear in such a position that they engage one another, when the stop rings are displaced into the press cylinder or out of it, the
The figures of the drawings show the following:
FIG. 1 is a schematic longitudinal section through an upper press cylinder of a hydraulic metal powder press in accordance with the invention;
FIG. 2 is a sectional view from above of a pressing table, taken along the line 22- in FIG. 3, and
FIG. 3 is a lateral view of. the upper press cylinder and of the parts mounted underneath it, in accordance with the present invention, as viewed from the same direction as the longitudinal section in accordance with FIG. 1.
As is evident from FIG. 2, a geared electric engine 1 drives, by way of a driving shaft, a snail 2 which mates with a worm gear 3. The worm gear 3 is connected in such a way that it will rotate a rotatable gland 5 that is pivoting in a cylinder bottom 4 of a press cylinder 9 (FIG. 1). The inside of the rotatable gland 5 has an axial longitudinal groove 21 in which a slide 6 is guided, which is attached to the lower part of a stop-sleeve 7. The stop'sleeve 7 has been designed in one part for smaller presses, but for larger presses, it has been designed in two parts, as shown here. The division in two parts has the advantage that a shaft packing 8 can be inserted at the joint between the two parts of the stop sleeve 7.
The upper part of the stop-sleeve 7 has been screwed into a corresponding thread of the press cylinder 9, by means vof a buttress thread 22, and its height can be modified by turning the stop-sleeve 7. g
The shaft supporting the snail continues as a worm shaft 11 for an additional snail 12, which mates with an additional worm gear 13 (FIG. 2). The additional worm gear 13 is joined in such a way that it will rotate a wormgear spindle 14, as may be seen in FIG. 3, and rotates it when the engine 1 is running. The worm-gear spindle 14 is supported by bearings 14a and 14b, which are mounted on the press cylinder 9, so that it can rotate. A micro-limit switch 15 is screwed on the wormsnail has to be supported in such a way that it may be shifted at a right angle to its longitudinal axis. This support that can be shifted, and the corresponding design of the snail are complicated.
his the purpose of this invention to design a hydraulic metal powder press, in such a way that the height of lift of the piston can be circumscribed as precisely as possible, without constant supervision.
Another purpose of this invention consists in the creation of a hydraulic metal powder press with a stroke limit for the press plunger, in which the stop constituting the limit supports a worm gear which can be driven by a snail placed in the machine frame, so as to be stationary. A further aim of the invention is to create a hydraulic metal powder press with a stroke limit for the press plunger, by means of which the press plunger is supported evenly and symmetrically within the frame of the machine. Further purposes and characteristics of the present invention will become apparent from the following description of a preferred example of its design, on the basis of the enclosed drawings, and from the claims.
gear spindle 14 by means of a threaded sleeve, details of which have not been shown, and is prevented from rotating as is evident from FIG. 3 by means of a projection 18 which protrudes inside between two parallel rods (18a) mounted at a distance from one another. Only one of the two rods 18a, which are also joined rigidly to the press cylinder 9, can be seen in FIG. 3. In the press cylinder 9, a piston 9a has been mounted in such a way that it may slide and be moved; it has a piston rod 9b. The piston rod 9b passes through the stop-sleeve 7 and its free end supports a pressing table 22. Seal 28 is positioned adjacent piston rod 9b at the location where piston rod 9b is led out of press cylinder 9. As may be seen from FIG. 3, a sliding bar 16 is rigidly attached to the pressing table 22 (e.g. screwed to it). This sliding bar 16 freely penetrates through an opening 23 of a base plate 24, in which the bearing 14b of the worm-gear spindle 14 has been mounted. To the press cylinder 9, a sleeve 25 has been attached, through which the sliding rod 16 also projects, and in which it is guided in such a waythat it is parallel to the worm-gear spindle 14. A stop pin 17 has been fastened to the sliding rod 16; the path of motion of the stop pin 17 agrees with the path of motion of the micro-limit switch 15 so that it may meet it during an approach. The distance between the stop pin 17 and the micro-limit swtich 15 is adjusted before the start of the operation of the hydraulic metal powder press in such a way that it is equal to the distance between the lower surface of the piston 9a and the upper stop face of the stop-sleeve 7.
On the engine frame, limit switches 19 and 20, which lie on top of one another in the path of motion of the projection 18, have been mounted; normally, they are closed.
As is evident from FIG. 1, an inlet opening a for the pressure medium has been provided at the upper end of the press cylinder 9, above the upper surface of the piston 9a. Below the bottom surface of the piston 9a, an outlet opening 10b has been made in the press cylinder 9; it is linked with an outlet duct 10c which is shown by a schematic drawing only and which leads to a reservoir R for the pressure medium; the reservoir is also drawn schematically only. In the outlet duct 100, an electromagnetic control valve V has been inserted, which is closed when the piston 9a is not moved, or when the stop-sleeve 7 as will be explained in detail later is not shifted. The electromagnetic control valve V is connected with electric supply lines of the engine 1, in such a way that its magnet is excited simultaneously with the swtiching on of the engine 1 by means of a switch S (FIG. 1). In the example of the design of the invention described, the pressure medium in the outlet duct 100 is under the same pressure that prevails also in the reservoir R. This pressure may be atmospheric pressure. But, it is also possible to use the duct 10c as a supply duct for a pressure medium under pressure, that is fed by a pump which has not been shown so as to bring back the piston 9a from its lower position once more into the upper original position as shown in FIG. 1. In this case, an additional valve which has not been shown may be inserted into the duct 10c; this valve establishes, during the return movement of the piston 9a, a connection with the pump which has not been shown.
When the stop-sleeve 7 is moved, the operation progresses as follows: When the switch S (FIGS. 1 and 2) is closed, the electromotor 1 is supplied with current and starts. In consequence thereof, the snails 2 and 12 will turn and rotate the associated worm gears 3 and 13, respectively. Due to the rotation of the worm gear 3, the rotatable gland 5 with the groove 21 will also rotate and, thereby, actuate in addition the stopsleeve 7 by way of the slide 6. Depending on the sense of rotation of the engine 1, the stop-sleeve 7 will be screwed by means of the thread 22 further into the press cylinder 9, or out of it. In that way, the position of its upper stop face changes, and thereby, the distance between that stop face and the bottom surface of the piston 9a also changes. Since the slide 6 can-slide axially in the slot 21 of the packing box 5, the adjustment'of the stop-sleeve 7 will not be impeded.
By means of the rotation of the worm gear 13, which takes place at the same time, the worm-gear spindle 14 is rotated, so that the micro-limit switch 15 which is kept from rotating by the projection 18 and the rods 18a, will be moved axially at the same speed as the stop-sleeve 7. Accordingly, its distance from the stop pin 17 changes by the same amount as thedistance between the bottom surface of the piston 9a and the upper stop face of the stop-sleeve 7.
Simultaneously with the closure of the switch S and with the start of the engine 1 which results therefrom, the magnet of the magnetic valve V is excited, so that it will open. In this way, it is possible, when the stopsleeve 7 is adjusted, by way of the duct 10c to expel the pressure medium out of the press cylinder 9 or to suck it into the press cylinder 9. It is evident from the circuit that the magnetic valve will remain open as long as the motor 1 is running, and the stop-sleeve 7 and the micro-limit switch 15 are moved thereby. When the switch S is reopened, the engine 1 comes to a stop, and the adjustment motion of the stop-sleeve 7 and of the micro-limit switch 15 is interrupted. In addition, the magnetic valve V closes again.
Once the stop-sleeve 7 has been moved into the desired position in the manner discussed in the preceding paragraphs, the piston 9a can be loaded with the pressure medium. To that end, the pressure medium is introduced into the press cylinder by way of the inlet opening 10a, while the magnetic valve V is opened at the same time. The pertinent circuit for the introduction of the pressure medium and for the opening of the magnetic valve V in the outlet duct 10c is well known and does not require any further explanation at this point. Due to the loading with the pressure medium, the piston 9a moves downward from the original position as shown in FIG. 1. In that way, the slide rod 16 which is fastened to the pressing table 22, slides within the aperture 23 and within the sleeve 25, and moves the stop pin 17 toward the micro-limit switch 15. When the bottom surface of the piston 9a reaches the upper stop face of the stop-sleeve 7, the movement of the piston 9a is arrested. At the same time, the stop pin 17 reaches the micro-limit switch 15 and causes thereby the lighting of a control lamp, which has not been shown. An operator will, therefore, be able to see that the motion of the piston 9a has been arrested. The limit switches 19 and 20, which interact with the projection 18 of the micro-limit switch 15, have been inserted into the circuit of the electro-motor l, in such a way that they break that circuit when they are run by the projection 18. In that way, it is made impossible that, during the movement of the stop-sleeve 7, the slide 6 leaves the groove 21 in an upward or downward direction. Therefore, the distance between the two limit switches 19 and 20 corresponds to the length of the groove 21.
We claim: 1
1. A hydraulic metallic powder press comprising a press cylinder, a piston displaceable in the press cylinder, a piston rod connected to the piston, a seal positioned adjacent said piston rod and ata location where the piston is led out of the press cylinder, a free end of the rod being positioned outside of the press cylinder and being attached to a die which is adapted to be in- I troduced into a cavity for compacting metallic powder contained therein, an adjustable sleeve provided in the press cylinder inwardly of said seal, said sleeve at least partially enclosing the piston rod and having an external thread, said press cylinder having an internal thread in mating relationship with said sleeve thread, the sleeve further having a slide, a rotatable gland at least partially enclosing said sleeve and having a longitudinal groove therein for guiding said slide, said groove running in the axial direction of the piston rod, a drive motor operatively coupled to said gland for rotatably moving said gland whereby said adjustable sleeve is moved axially and the length of the stroke of the die into the cavity is varied, and means for introducing and for causing the movement of said die.
2. An hydraulic metallic powder press as in claim 1, further comprising a spindle mounted adjacent to and outside of the press cylinder, said drive motor coupled to said spindle to rotate said spindle, a first limit switch mounted on said spindle for indicating when said piston contacts said sleeve, so as to move axially along said spindle when said spindle is rotated and by the same axial amount as said sleeve, a slide rod mounted for movement with the piston rod, said slide rod being disposed outside the cylinder and displaceable parallel to the piston rod, and a stop pin mounted on said slide rod and positioned in the path of movement of said first limit switch so that said first limit switch is actuated when said piston contacts said sleeve.
3. An hydraulic metallic powder press as in claim 1,
in which the external thread on the sleeve and the internal thread of the press cylinder are buttress threads.
4. An hydraulic metallic powder press as in claim 2, further including second and third limit switches for stopping said drive motor when said sleeve has been moved axially a predetermined distance and a cam mounted on said first switch to actuate said second and third limit switches when said sleeve has been moved axially a predetermined distance.
5. An hydraulic metallic powder press as in claim 1 in which the means for introducing and removing a pressure medium from the pressure cylinder include valve means.