US 2941428 A
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Filed June 15, 1959 June 21, 1960 F. L. RIGGIO ErAL- 2,941,428
STAKING APPARATUS 2 Sheets-Sheet 1 mIiIElEL mil QI TOENEYS F. RIGGIO EFAL swAxmc APPARATUS 2 Sheets-Sheet 2 Filed June 15, 1959 5 a 0 a 0 6 u 2 2 w /w 3 9 2 mm? m A MGM E WAGE N T o d LS "H Al lfif. A A A III}! A! .f m f F H A 6 3 8 l M w a 2 QM 8 u 0 a 2 a a m w w /4 A lllllll YJHHII a A V 0 M M k Fail STAKING APPARATUS Frank L. Riggio, Essex, and Alfred B. Strempel, Deep River, Conn., assignors to Cramer Controls Corporation, Centerbro'ok, Conn, a corporation of Connecticut Filed June 15, 1959, Ser. No. 820,304
6 Claims. (Cl. 78-42) This invention relates to apparatus for interconnecting two parts by a staking operation, and more particularly to an improved staking press of relatively simple and compact construction which can be operated quickly and easily for mass production.
In the usual staking operation, two metal parts to be joined are placed on a supporting base in an assembled relation in which a detent on one part (the lower part) extends through a hole in the second part (the upper part) and projects slightly above the upper surface of the-second part, the detent extending from a shoulder of the first part which engages the second part adjacent the hole. The top of this detent is subjected to a hammer blow applied through a staking punch, thereby spreading the metal over the top of the second part around the hole therein. Such a staking operation requires holding the parts together in their assembled relation prior to the staking blow, and application of the hammer blow to the staking punch while it is accurately aligned with the detent.
With the apparatus of the present invention, the steps incident to the usual staking operation can be performed easily in rapid succession.
A staking apparatus made in accordance with the invention comprises a base for supporting the assembly of parts to be joined, a frame having an upper section and a lower section overlying the base, and a hollow pressing punch slidably mounted in the lower section of the frame for vertical movements toward and away from the base, the pressing punch having a lower end engageable with the assembly to hold it in position on the base. A staking punch is slidable in the pressing punch and has a lower end adapted to engage the detent of the lower part of the assembly when the latter is .engaged by the pressing punch. A hollow ram is movable vertically in the upper section of the frame and contains an air cylinder, and actuating means are operatively connected to the ram for urging it downward to press the pressing punch against the assembly on the base, thereby holding the parts firmly together in their assembled relation. A piston is slidable vertically in the air cylinder in the ram and is engageable at its lower end with the upper end of the staking punch, the piston being urged upwardly in the cylinder by a biasing means. A compressed air line is connected through a valve to the upper portion of the air cylinder. Thus, by operation of this valve to admit compressed air into the cylinder, the piston is actuated downwardly against the biasing means and is thereby impacted against the upper end of the staking punch, whereby the latter is hammered downwardly in the pressing punch and against the detent of the assembled parts when the assembly is held by the press ing punch.
In the preferred construction, the ram is separable from the pressing punch and is urged upwardly in the frame by a second biasing means, thereby permitting easy replacement of the pressing punch and the staking punch to accommodate different assemblies of parts to ,be staked 2,941,428 Patented June 21, 1960 of the new staking press, with parts broken away for illustrative purposes;
Fig. 2 is a vertical sectional view of the ram illustrated in Fig. 1, showing the piston in its normal raised position in the ram; and
Fig. 3 is a view similar to Fig. 2 but showing the piston in its lower position in the ram, to which position the piston is actuated for the staking blow.
Referring to the drawings, the reference numeral 10 designates a base for supporting an assembly of two parts to be staked together. As illustrated, these parts comprise a lower part 11 resting on the base and supporting an upper part 12 which is provided with a hole for receiving a detent 11a of the part 11. The part 12 rests on a shoulder formed by the detent 11a, and the latter fits closely in the hole in the part 12 and projects somewhat above the upper surface of the part 1 2. The base 10 also supports a frame 13 having an upper section 14 and a lower section 15 which overlie the work-supporting portion of the base.
A hollow pressing punch 17 is slidably mounted in the lower frame section 15 for vertical movements relative to the base 10. The punch 17 is of cylindrical form and extends through a replaceable bushing 18 in which the punch has a close sliding fit. The bushing 18 may be releasably secured to the lower frame section 15 in any suitable manner, as by screwing it into a threaded opening extending vertically through the section 15. Thus, the bushing 18 may be replaced to receive a punch 17 of different diameter, so as to accommodate a difierent assembly of work pieces 11-1 2. At its upper end, the pressing punch 17 has a flanged head 17a for 1imit ing downward movement of the punch in the bushing 18. As shown, the punch 17 is normally urged upwardly by biasing means in the form of a compression spring 19 coiled around the punch between its head 17a and the bushing 18. The spring 19 normally holds the pressing punch in a raised position wherein the assembly of work pieces 11-42 will just clear the lower end of the punch, thereby facilitating movements of this assembly to and from the proper staking position directly under the punch. When the punch 17 is lowered to its pressing or hold-down position, as shown in Fig. l, the lower end of the punch engages the work part 12. around the projecting detent 11a so that the parts 11-1=2 are held securely in their assembled pre-staking positions on the base 10.
A staking punch 21 extends downward through the hollow pressing punch 17 and is slidable vertically therein. At its upper end, the staking punch 21 has a flanged head 21a for limiting downward movement of this punch in the pressing punch 17. The inner punch 21 is of substantially greater length than the outer punch 17 so that when the head 21a rests on top of the punch 17, the lower end of punch 21 protrudes below the bottom of punch 17. Accordingly, when the pressing punch 17 is urged downward against the workpiece 1 2, as previously described, the top of detent 11a engages the lower end of staking punch 21 and raises the latter in the pressing punch 17, as shown in Fig. 1. In this position of the punches, the staking punch 21 is adapted to be driven downwardly in the holding punch 17 so as to effect the staking operation.
A ram 23 is mounted for vertical sliding movements in the upper frame section 14. The ram 23 is of cylindrical form having a close sliding fit in a vertical bore in the section 1'4. The latter has a vertical slot 14a which receives a detent or pin 23a projecting laterally from the ram 23, so that the pin 23a and coacting slot 14a serve to limit the upward and downward movements of the ram. A compression spring 24 is coiled around the ram between the frame section l4 and a cap 25 screwed on the upper portion of the ram, the spring 24 thus serving as a biasing means for urging the ram upwardly relative to the frame. The ram is adapted to be depressed against spring 24 by actuating means in the form of a lever 26 mounted on a pivot 27 secured to the frame section 14, the lever intermediate its ends being in overlying engagement with the pin 23a on the ram. The spring 24 normally holds the ram and its actuating lever 26 in raised positions; but by swinging the lever 26 downwardly about its pivot 27, the ram is moved toward its lower position as shown in Fig. l.
The ram 23 contains'an air cylinder 28, the upper endof which is defined by .the cap 25. At its lower portion, the cylinder 28 has a reduced section 28a located above a shoulder 28b, and below this shoulder the cylinder has a further reduced section 280 opening through the lower end of the ram. A piston 29 is slidable vertically in the cylinder 28-2c and is provided at its upper end with an enlarged head 29a which fits closely in the main cylinder portion 28, the piston 29 having a close sliding fit in the intermediate cylinder section 28a. The lower portion of piston 29 is reduced, as shown at 2%, so that it is adapted to enter the cylinder portion 280 with a close sliding fit. Downward movement of the piston in the ram is limited by engagement of shoulder 28b with the shoulder formed between the piston parts 29 and 2%, as shown in Fig. 3.
The piston 29 is urged upwardly in the ram by a biasing means in the form of a compression spring 30 coiled around the piston between its head 29a and an internal shoulder 28d of the ram. Accordingly, the piston is normally held in a raised position wherein the head 28a engages the cap 25 of the ram.
The piston 29 is adapted to be actuated downwardly by compressed air from a pneumatic line 32 in the form of a flexible hose. A valve 33 is interposed between the compressed air line 32 and the upper portion of cylinder 28. As shown, the valve 33 has a housing 34 and a nipple 35' which is screwed into a threaded opening 25a in the cap 25. The valve 33 also comprises a rotor 36 which normally cuts off communication between the air line 32 and the ram cylinder 28 while venting the latter cylinder to atmosphere through an air vent (not shown). By means of a handle 37, the rotor 36 may be rotated to an operating position for closing the air vent and admitting compressed air to the upper portion of cylinder 23. While the valve 33 may take various forms, we prefer to employ a conventional air valve of the quickopening type which, by actuation of the handle 37, admits compressed air at its full pressure practically instantaneousiy from line 3?. into the cylinder 28, so that the piston is urged with an impact by the compressedair. When rotor 36 is returned to its non-operating position by handle 37, after completion of the impact stroke of piston 29', the latter is returned to its raised position by springfid.
The cylinder 28 is proved with an air vent 38 which is normally separated from the compressed air inlet opening by the piston head 29a. However, upon actuation of t e piston to its lowermost position, as shown in Fig. 3, the head 2% moves below the vent 38 and thereby permits discharge of the compressed air through this vent. Thus, after movement of valve 33 to its operating position, it may be left in this position without subjecting the depressed piston 2? to the full pressure in the compressed air line 32.
In the operation of the apparatus, the lever 26 is swung downwardly on its pivot 27 to depress the ram 23 against the head 17a of the hold-down punch 17, so that the latter tightly engages the work piece 12 and holds the assembly 11-42 firmly in the proper staking position on the base 10. The valve handle 37 is then operated to open the valve 33 and admit compressed air to the uper portion of cylinder 2? Consequently, the piston 29 is driven downwardly against the action of spring 30 and is impacted against'the protruding upper end of the staking punch 21. The resulting hammer blow on this punch drives it downwardly in the holddown punch 17 to effect the staking operation in the manner previously described. Upon release of the ram lever 26, the spring 24- returns the ram to its raised position, thereby allowing the spring 19 to raise hold-down punch 17 from the work assembly 11-12. The latter may then be removed from the press and a new assembly substituted, whereupon the operations are repeated.
Due to the air vent 38, the downward blow of piston 29 on the staking punch 21 is entirely an impact blow developed by the mass of this piston and the velocity imparted to it by the compressed air from line 32. The force of the blow is developed during the downward stroke of the piston 29 prior to uncovering of vent 38; and when this vent is uncovered to permit escape of compressed air, the further downward movement of the piston is due only to its momentum. Accordingly, after the piston has struck the punch 21, there is no air pressureto recoil the ram 23 or develop strain in frame 13.
When the lever 26 is released after completion of a staking operation, it is swung upwardly by spring 24 into engagement with a stop 40, which normally holds the lever 26, ram 23, and holding punch 17 in intermediate retracted positions to allow replacement of the previously staked assembly by a new one to be staked. The stop 40 is mounted for swinging movement on a pivot .41 secured to frame 13 but is normally engaged by a pin 42 which locates the stop in position to 'be engaged by lever 26. By swinging the stop 40 upwardly, the ram'23 can be raised to an extreme retracted position in which pin 23a is disposed in the upper end of slot 14a. In this extreme retracted or upper position of ram 23, the hold-down punch 17 and staking punch 21 may be lifted from the bushing 18 and replaced by diiferent punches to accommodate different sizes and shapes of work pieces.
As will be apparent from the foregoing, the new apparatus-maybe operated quickly and easily to perform the staking operations in rapid sequence, and lends itself easily to change-over for accommodating diiferent sizes and shapes of-work pieces.
1. A staking press for interconnecting two assembled parts, which comprises a base for supporting the assembly of parts, 'aframe having an upper section and a lower section overlying the base, a hollow pressing punch slidably mounted in said lower section for vertical movements toward and away from the base and havinga lower end engageable with said assembly to hold it in position on the base, a staking punch slidable in the pressing punch and having a'lower end adapted to engage one of said parts when the assembly is engaged by the pressing punch, a hollow ram movable vertically in said upper section and containing an air cylinder, actuating means operatively connected to the ram for urging it downward to press said pressing punch against the assembly on the base, a piston slidable vertically in said cylinder and engageable with the upper end of the staking punch, biasing means urging the piston upwardly in the cylinder, a compressed .air line, and a valve for connecting said air line to the upper portion of the cylinder to actuate'the piston downwardly against said biasing means and thereby impact the :piston :against the upper-endof the staking punch,
whereby said staking punch is hammered downwardly in the pressing punch and against said one part when the assembly is engaged by the pressing punch.
2. A staking press according to claim 1, in which the ram is separable from the pressing punch.
3. A staking press according to claim 1, comprising also a second biasing means urging the ram upwardly relative to the frame.
4. A staking press according to claim 1, in which the ram is separable from the pressing punch, the press comprising also a second biasing means urging the ram upwardly relative to the frame, and a third biasing means urging the pressing punch upwardly relative to the frame.
5. A staking press according to claim 1, in which the cylinder has an air vent normally closed from the upper portion of the cylinder by said piston, the vent being located to exhaust air from said upper portion of the cylinder only when the piston is actuated downwardly toward the staking punch.
6. A staking press according to claim 1, in which the 20 ram is separable from the pressing punch and is movable 6' to a fully retracted position in which said punches are removable from said lower section, the press comprising also an adjustable stop for limiting retraction of the ram to an intermediate retracted position in which the pressing punch is engageable with the ram while the pressing punch is slidably mounted in said lower section.
I References Cited in the file of this patent UNITED STATES PATENTS 517,172 Nicolai Mar. 27, 1894 812,787 French Feb. 13, 1906 863,346 Berry Aug. 13, 1907 1,196,656 Bugbee Aug. 29, 1916 1,523,359 Leggett Jan. 13, 1925 2,113,161 Osborne Apr. 5, 1938 2,332,935 Schlack Oct. 26, 1943 2,364,420 Bloss Dec. 5, 1944 FOREIGN PATENTS 564,290 France Dec. 26, 1923