US2737066A - Drop hammer - Google Patents

Description

March 6, 9 F. RIEMENSCHNEIDER DROP HAMMER 3 Sheets-Sheet 1 Filed June 12, 1952 INVENTOR: Fk/Tz E/EMENSYHNE/DEE,

DROP HAMMER Filed June 12, 1952 3 Sheets-Sheet 2 I N V EN TOR. f2! TZ EIEAM'NSOWVE'IDEB H S HGE/YTS.

March 6, 1956 F. RIEMENSCHNEIDER 2,737,066

DROP HAMMER Filed June 12, 1952 5 Sheets-Sheet 5 FRITZ izlemeflscwaofe,

HIS AGENTS.

United States Patent DROP HAMMER Fritz Riemenschneider, Leverkusen Schlebusch, Germany, assignor to Eumuco AWG. fiir Maschinenbau, Leverkusen-Schlebusch, Germany, a German corporation Application June 12, 1952, Serial No. 293,174 Claims priority, application Germany June 14, 1951 1 Claim. (Cl. 78-3l) The invention relates to drop hammers and relates more particularly to drop hammers of the type wherein the hammer head is suspended from a flexible chain.

Desirable features for a drop hammer include the development of suitable drop energy by the hammer head, and this is generally speaking well accomplished by such machines now in use. However, present drop hammers are deficient therein that they have too great a length of fall, usually of up to 7 feet or more, which brings about that only low drop frequencies can be had.

It is among the principal objects of the instant invention to provide a drop hammer with a high drop frequency, having a comparably great weight of hammer head and a smaller length of fall.

In order to increase the drop frequency, it is desirable to arrange for speedy lifting of the hammer head. At the same time, owing to the great weight of the head, it is advantageous to keep the lifting power within reasonably low proportions. For this purpose, particular lifting mechanism is arranged which comprises a specially shaped lifting cam, as will be more fully explained hereinbelow.

With the above and other objects of the invention in view, the invention consists in the novel methods, construction, arrangement and combination of various devices, elements and parts, as set forth in the claim hereof, one embodiment of the same being illustrated in the accompanying drawings and described in the specification.

In the accompanying drawings,

Fig. l is a front elevational view, partly in section, showing a drop hammer in accordance with the invention;

Fig. 2 is a sectional view taken on line 22 of Fig. 1;

Fig. 3 is a sectional view taken on line 33 of Fig. 1;

Fig. 4 is a large scale elevational view of the lifting cam shown in Fig. 1 but, for the sake of clarity and simplicity, showing the cam in plain outline; the cam is illustrated in position before lifting;

Fig. 5 is an elevational view similar to Fig. 4, but showing the cam after slightly more than a one-quarter lifting turn;

Fig. 6 is a fragmentary elevational view of a lifting chain in accordance with the invention; and

Fig. 7 is a sectional view taken on line 77 of Fig.. 6.

In carrying the invention into effect in one of the embodiments which has been selected for illustration in the accompanying drawings and for description in this specification and referring now particularly to Figs. 1 and 2, there is provided a drop hammer generally indicated at 11 which has a base 12 and an anvil 13 arranged thereon. A lower die 14 is exchangeably secured to the anvil 13. Two upright legs 16 and 17 surmount the base 12, each having a guide 18 for guiding therebetween a hammer head generally indicated at 19.

The hammer head 19 has on its lower side an upper die 21 that is interchangeably secured to the head 19, and is in registry with the lower die 14.

A bridge 22 is supported by the legs 16 and 17' and carries a mechanism generally designated 23 for lifting, holding and respectively releasing the hammer head 19.

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A lifting chain 24 is interconnected to the hammer head 19 and to the mechanism 23. The chain 24, as best shown in Fig. 2, carries on its lower end a rod 26 that protrudes to the interior of a chamber 27 that is formed on the interior of the hammer head 19. The rod 26 has on its lower end a mushroom-shaped enlargement 28 that is normally disposed about midway of said chamber 27 and is spaced above the bottom of said chamber 27. Said enlargement 28 supports a disc 29 which, in turn, supports a resilient material 31, such as several layers of rubber sheet or the like, within said chamber 27. A platen 32'covers the top of the chamber 27 thereof, and provides an abutment for the resilient material 31, preventing removal of the resilient material upwardly from the chamber 27. The platen 32 is removably secured to the head 19, for instance, by means of a key 33, as shown in Fig. 1, and has a central opening 34 for the rod 26, and the opening 34'is wide enough to permit sideward swinging movement of the rod 26.

The lifting mechanism 23 comprises a lifting cam 36 that is secured to a horizontally disposed rotatable shaft 37. The upper end of the link chain is secured to the lifting cam 36 at an attachment point 38 thereof.

The length of fall of the drop hammer in accordance withthe'invention is about fifty-one (51) inches, and in a preferred embodiment is only about thirty-nine (39) inches. Accordingly, in the preferred embodiment, the circumference 39 of the'cam 36 which preferably corresponds to the length of fall, has a rectified length of thirty-nine inches. During lifting, the chain 24 is wound up on said circumference 39.

The said shaft 37 that carries the cam 36 is rotatably journalledin anti-friction bearings 41 which are supported in the bridge 22. Said shaft 37 carries on one side a brake, generally indicated at 42, and on the other side a'clutch, generally designated 43. The brake 42 includes a stationary part 44 which is supported on the bridge 22, and a movable part 46 that is keyed to the shaft 37. Means are provided, for instance, one or more springs 47 operable to normally interengage the movable part 46 with the stationary part 44, to hold the shaft 37 normally still. There are provided release means such as hydraulic means (not shownin detail) fed by a hydraulic conduit 48, to release the brake to permit rotation of the shaft 37.

The said clutch-43 comprises a single inner lamella 49 that is keyed to, and rotatable with, the shaft 37, and two outer lamellae 51 and 52, one on each side of the lamella 49. Said outer lamellae 51 and 52 are rotatable about the axis of the shaft 37 and furthermore are movable in opposite directions axially of the shaft 37 for releasable frictional engagement of the inner lamella 49 of the shaft 37. Said outer lamellae 51 and 52 are dis posed in a housing 53 that is rotatably journalled, by means of a journal bearing 54 on the shaft 37, so that rotation of the housing 53 and frictional interengagement of the lamellae 59, 51 and 52 will cause rotation of the shaft 37. A plunger 56 is provided which is reciprocably movable axially of the shaft 37 to actuate, and to release, the movable lamellae 51 and 52, and which is actuable by means ofa pneumatic mechanism generally indicated at 57.

The rotatable'housing 53 carries cooling fins 58 and is provided'on its' outer circumference with gear teeth 59 that mesh with a pinion 61. Said pinion 61 is mounted on a shaft (not shown) coaxially with a pulley 62 that is driven by means of a plurality of belts 63 from a motor 64. The motor 64 and the shaft carrying the pinion 61 and the pulley 62 are supported on the bridge 22. Means, such asdogs' 66, may be provided for controlling the pneumatic circuit 67 for the mechanism 57 and the conduit 48, and means, suchas a pedal 68, may be provided to actuof the conduit 67 are well known, and therefore not described in full detail herein. 1

The cam 36 has eccentrically arranged an opening 71 with which it is mounted on the shaft 37, and keyed thereto at 72 and 73. The circumference 39 includes a section between the points A and B that is concentric with the center C of the opening 71, and the said center C coincides with the axis of rotation of the shaft 37. Between the points B and D on the circumference 39, the radii from the center C increase continuously, and between D and E decrease again. The are between B and E may be circular and described about a center point F which is disposed on the line BCD and spaced thereon from the center C. Accordingly, when the lifting cam 36 rotates in the direction G from the initial position shown in Fig. 4, towards the position in Fig. 5, it has moved about the center C for an angle H somewhat in excess of a right angle; throughout the rotation for the angle H, the speed of lifting of the chain 24 will be linearly proportional to the angular speed of the cam 36 as it rotates about the center C. As best shown in Fig. 5, the chain 24 will after the rotation for the angle H make contact with the point B on the circumference 39. Between the points Band D, it will be noted, the lifting speed of the chain 24 will be increased as compared to the speed between A and B assuming continued steady angular rotation of the shaft 37, and thereafter, between D and E, the lifting speed of the chain 24 will again be decreased as compared with the speed between B and D. The cam 36 may have holes (see Figs. 4 and 5) to reduce the weight thereof. As mentioned before, the circumference 39 is so dimensioned, that during lifting the length of chain available for lifting will be entirely rolled-up on the circumference 39.

In accordance with a preferred embodiment, a special chain 24 may be provided, shown in Figs. 6 and 7. It comprises inner links 74, and paired outer links 76 as well as connecting bolts 77 and nuts 78. Each inner link 74 comprises a bar 79 that has on both ends opposite integral bosses 81. Each boss 81 rests in a matching cavity of an outer link 76, in order to take up the stress, thereby relieving the bolts 77 of any shearing stress. Each of the outer links 76, furthermore, is provided with recesses 83 to reduce the weight thereof.

The operation of the drop hammer is as follows.

The motor 64 is started, and will turn the pulley 63, which will rotate the pinion 61 and, by means of the gear teeth 59, rotate the housing 53. The spring 47 will actuate the brake mechanism to hold at standstill the shaft 37.

Operation of the pedal 68 will actuate the circuit 67, and thereby the brake 42 will be released, against the action of the spring 47, and at the same time the plunger 43 will actuate the clutch 43. Thereupon, the lamellae 51 and 52 will frictionally engage, and turn, the lamella 49, thereby rotating the shaft 37. The lifting cam 36 will rotate with the shaft 37, and will lift the link chain 24. The rod 26 will thereby press upwardly against the disc 29, the pressure thereof will be taken up by the resilient means 31 and by the platen 32, and the hammer head 19 will be lifted, sliding between the guides 18.

The lifting impact between the chain 24 and the head 19 will be gentle, owing to the take-up of the pressure by the resilient means 31. The shaft 37 will rotate at uniform speed; however, the lifting of the chain 24, due to the shape of the circumference 39 of the cam 36 will first be slow, thereafter be accelerated, and thence be decelerated before reaching the end of the upward stroke. The lifting will be completed after a single turn of the cam 36.

Upon reaching the upper extreme position, the head 19, by means of the upper dogs 66, will actuate the circuit 67, so that the flow of compressed air to the brake 42 and to the clutch 43 is cut-off, and instead these parts are opened to the atmosphere. Thereupon, the brake 42 will be actuated by the spring 47 arresting the rotation d of the shaft 37, and the plunger 56 will release the lamellae 51 and 52, uncoupling thereby the clutch 43. The motor 64, the pinion 61 and the housing 53 will continue to turn idling.

If a fall of the hammer head 19 is desired, the brake 42 will be released by the operators by supplying compressed air through the conduit 48. Thereafter, the hammer head will descend under its own weight, releasing its energy to a workpiece that may be held between the dies 14 and 21. The combined small length of fall and great weight of the hammer head 19, will release a large energy onto the work piece. Near the end of the downward stroke of the hammer head 19, it may, if the machine is so set, actuate the lower dog 66 to initiate the lifting stroke. Instead of such automatic regulation, a regulation of the upward and downward stroke succession may be arranged for hand or foot operation.

Owing to the short length of fall, a high drop frequency can be attained, which, for instance during drop forging, enables an excellent utilization of the heat within the work piece. This makes it possible to use dies suitable for pre-forging as well as for finishing forging, obviating the use of separate special dies for each operation.

At the end of the descent of the hammer head 19, the rod 26 will for a short distance, proceed downwardly within the chamber 27 in the free space formed below its normal position, and will thereby avoid any impact damage to the links of the chain 24.

Certain of the advantages of the invention have already been herein referred to. It may be useful, however, to allude particularly at this point to the advantage provided by the shape of the cam 36, which enables the developing of the necessary lifting acceleration for the chain and hammer head without the necessity for excessive power to drive the cam. This also helps to keep the dimensioning of the clutch 43 within reasonable limits.

It will be apparent to those skilled in the art that the novel principles of the invention disclosed herein in connection with specific exemplifications thereof will suggest various other modifications and applications of the same. It is accordingly desired that in construing the breadth of the appended claim it shall not be limited to the specific exemplifications of the invention described herein.

Having thus described the invention, what I claim as new and desire to be secured by Letters Patent, is as follows:

In a drop hammer, in combination, a frame defining a guide way, a hammer movable in said guide way and a mechanism for lifting said hammer head comprising power means and a cam supported by said frame, a clutch and brake operatively connected between said power means and said cam for driving the cam through one revolution and releasing the same, means for actuating and for releasing said brake and clutch, an elongated flexible lifting means connected at one end of said hammer and at the other end to said cam, said lifting means being adapted to be carried around the circumference of said cam when the same is used for lifting the hammer, and said cam having a circumference for receiving said lifting means which includes a minor first portion concentric with the axis of rotation of said cam, an adjacent second substantial portion having increasing radii from said axis and a third minor portion having decreasing radii from said axis whereby the lifting of said hammer is started at a uniform speed, then an accelerating speed through the major path of travel of said hammer and then a decelerated speed prior to release of said hammer.

References Cited in the file of this patent UNITED STATES PATENTS 463,574 Hammesfahr Nov. 17, 1891 629,737 Bassett July 25, 1899 1,324,925 Rice Dec. 16, 1919 1,614,419 Brewster Jan. 11, 1927 1,720,592 Fitzgerald July 9, 1929

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