US3499334A

US3499334A - Drive for a feed device

Info

Publication number: US3499334A
Application number: US678416A
Authority: US
Inventors: Karl Griesinger
Original assignee: L Schuler GmbH
Current assignee: L Schuler GmbH
Priority date: 1966-11-07
Filing date: 1967-10-26
Publication date: 1970-03-10
Anticipated expiration: 1987-03-10
Also published as: GB1150750A; DE1552092A1

Description

March 10, 1970 K. GRIESINGER 3,499,334

DRIVE FOR A FEED DEVICE Filed Oct. 26, 1967 3 Sheets-Sheet 2 77 36 mm J7 MJ/emenf 0f slide 75 fine mm e/wa/ of 1mm 1' 360 of a'r/re crank! 7 INVENT OR ATTORNEYS March 10, 1970 K. GRIESINGER DRIVE FOR A FEED DEVICE 3 Sheets-Sheet 5 Filed Oct. 26, 1 967 0 p m IA INVENT OR KARL GRIESINGER 2L $2M v M ATTORNEYS United States Patent 3,499,334 DRIVE FOR A FEED DEVICE Karl Griesinger, Goppingen-Jebenhausen, Germany, assignor to L. Schuler G.m.b.H., Goppingen, Germany Filed Oct. 26, 1967, Ser. No. 678,416 Claims priority, application Germany, Nov. 7, 1966, Sch 39,790 Int. Cl. F16h 21/32 US. Cl. 74-40 9 Claims ABSTRACT OF THE DISCLOSURE A drive for a feed device for workpieces, particularly useful in conjunction with presses, driven by a rotary shaft with the aid of a cam guide and stationary in the reversal points of a reciprocating motion, including two slide members guided for reciprocal motion in a transporting direction, one of which derives an oscillating motion from a crank operatively connected with the rotary shaft, wherein the two slide members are coupled for conjoint motion except for swinging movement executed by the slide member in the zone of the reversal points of their reciprocal motion at which point a curved guide means causes a relative motion between the two slide members such that one slide is slowed with respect to the other in the zone of the reversal points.

This invention relates to a drive for a feed device for workpieces, which is utilisable in particular in conjunction with presses and which is driven by a rotating shaft with the aid of a cam guide and is stationary in the reversal points of a reciprocating movement.

Known feed devices of this type, for example devices which grip a workpiece, advance it a certain distance and release it, and which thereupon return to their starting position, are controlled by a rotating cam through suitable lever linkages. The lever linkage connected to the feed device is stationary as long as a part connected to the lever linkage acts on a concentric portion of the rotating cam. The lever linkage and consequently also the feed device move when a movement is imparted to the linkage through a correspondingly shaped portion of the cam. The disadvantages of these cam controls consist in particular in that all the movements must be produced and the moments of inertia overcome by the cam or by a guide replacing the latter, so that the forces acting on the control cam or on the flanks of a guide are extremely great. This in turn entails large contact surfaces and consequently great masses, and thus also high moments of inertia. In addition, such heavy loading of flanks leads to considerable wear. Since precisely those parts of the cam which may also consist of curved guides are difiicult to produce, wear on these parts is particularly troublesome. Speaking quite generally, such heavily loaded cam controls are components which frequently give trouble, particularly when they are dirty, so that components of this type are avoided whenever possible. The problem underlying the invention is to develop feed devices of the abovedescribed type, in which the cam controls are subjected to smaller loads.

The invention consists in that the feed device has two slide which are guided for movement in the feed direction and one of which performs an oscillating movement, derived from a crank, along the feed direction, that the second slide is connected to the first slide by a coupling member, that with the exception of the region of the reversal points of the first slide the two slides are coupled for movement synchronously with one another by the coupling member, and that in the region of the reversal points of the movement of the first slide the coupling Patented Mar. 10, 1970 member on the other hand cooperates with a cam which cancels the movement-producing coupling and permits a relative movement of the two slides in relation to one another in such a manner that the second slide is stationary in that region.

The particular advantage of the invention consists in that in this manner a to-and-fro oscillating movement of the second slide is obtained, the latter being stationary for a certain time at the points of reversal of its movement, so that this standstill time can be used to grip the workpieces by means of suitable devices or to perform movements which must be performed from a stationary device, for example in the engagement of gripper devices in recesses, or the like.

The particular advantage of the invention consists in that both slides, and thu also the feed device, which may have one or more grippers, are accelerated and braked by the crank, and that from the cam control there is derived only a control movement or a relative movement for the production of which great force is not required. Another advantage of the invention consists in that the cam controls are limited to small movement portions. Since they have to produce only a relative movement, they may be disposed in the path of the feed device.

The relative movements which have to be produced by the cam control also amount in magnitude to only a fraction of the total slide movement. The movement derived from the cam control therefore also does not need to he stepped up, so that the transverse forces applied by the cam are relatively small.

Which movements are produced by the guides disposed in the region of the reversal points of the first slide depends on the further development of the invention. For example these guides may provide control movements which uncouple the second slide from the first and, after the first slide has passed through the reversal point, recouple the two slides together. In a preferred embodiment of the invention however the guide produces a movement which is transmitted to the second slide and is oppositely directed to the movement of the first slide and is so selected that the movement of the first slide is just compensated and consequently the second slide is stationary. To this end the relative movement compensating the movement of the second slide is derived from a part of the coupling member cooperating with a cam, said part moving with the first slide. In this arrangement the cam may in turn be so selected that the movement on it is relatively great, so that favourable force conditions can be selected. The coupling member between the first and second slides may in turn be of various constructions. For example the coupling member may have an angle lever mounted in the first slide, while the end of one arm of said lever cooperates with the cam in the region of the reversal points and the other arm is connected by a link to the second slide. The cam control is then therefore so selected that in the region of the reversal points of the first slide the angle lever is rocked about its axis and thus produces a relative movement between the first and second slides. This embodiment of the invention can be further developed so that in the region between the reversal points of the second slide the arm of the angle lever which cooperate-s with the cams i guided in a guide extending parallel to the feed direction, so that during this portion of the path the free angle lever arm cooperating the cams at the reversal ponts is likewise held and permits no rocking movement of the angle lever, so that in this region the two slides move absolutely identically, just as if they were rigidly connected together.

In one embodiment of the invention the crank driving the slides does not act directly on the first slide, but acts thereon through a lever transmission which increases the oscillating movement of a push-rod swinging to-an-fro and connected to the crank.

If the feed path over which the workpieces are to be advanced is as large as the oscillating movement of the second slide, it is suificient for a carrier connected to the second slide to be provided with a gripper device. In many cases however the feed path is larger than the oscillating movement of the feed device. In this case a plurality of grippers are fastened on a carrier which is connected to the second slide and which, when three or more grippers are used, is substantially longer than the amplitude of the oscillating movement, the distance between said grippers corresponding to the amplitude of the oscillating movement. A workpiece gripper than always picks up again and advances the workpiece which has been advanced and laid down by the neighbouring workpiece gripper. A numerical example will explain this. The distance to be travelled amounts for example to 4.50 metres. If in this case the amplitude of the oscillating movement of the second slide amounts to 1.50 metres, the carrier fastened on the second slide must have a length of at least 3 meters and must carry three grippers, the distance between which amounts to 1.50 metres. The first gripper then advances the workpieces a distance of 1.50 metre in accordance with the amplitude of the oscillating movement, and then lays it down. The carrier then swings back, the second gripper seizes the workpiece and advances it again in accordance with the amplitude of the oscillating movement, while in the next oscillation the workpiece is seized by the third gripper and advanced to the end of the path to be travelled.

In many cases in practice it is entirely sufficient for the feed device to perform a to-and-fro swinging movement, while said device is stationary at the end points of this oscillating movement. It is however also frequently desirable that at the end points of the oscillating movement a lifting movement should also be performed, perpendicularly to this oscillating movement, luring the standstill time. In one embodiment of the invention a lifting movement of this type is now derived from the movement which the two slides perform relative to one another. Since the relative movement between the two slides also reverses its direction at the reversal point of the first slide, in a particularly simple embodiment of the invention this lifting movement can be derived from a crank which is driven in a reciprocating oscillatory movement by the relative movement of the two slides. If in addition it is desired to achieve the effect that the lifting movement likewise becomes stationary in the region of its stroke point, the lifting path of the carrier can be limited by stops in the movement phase during which the first slide passes through its reversal point, and the remainder of the lifting movement transmitted by the crank can be absorbed by a resilient connection. The effect is thereby achieved that the carrier is absolutely stationary for a finite period of time both in respect of the movement of translation and in respect of the lifting movement, although the feed device is driven by a rotating main crank.

Further features of the invention will be seen from the following description of an embodiment of the invention, in conjunction with the claims and with the drawing. The individual features may be utilised either independently or in combinations of a plurality thereof in an embodiment of the invention.

An embodiment of the invention is illustrated in the drawing.

FIGURE 1 illustrates the parts necessary for understanding the invention in elevation, partly in section,

FIGURE 2 shows a section on the line IIII in FIG- URE 1.

FIGURE 3 represents a simplification of the device according to FIGURE 1, for the purpose of illustration of the interconnection of the two slides,

FIGURE 4 represents a perspective view of the connecting members interposed between the two slides,

FIGURE 5 represents a sectional view along line VV of FIGURE 1,

FIGURE 6 represents a prospective view of the carrier and for supporting columns of the device, and

FIGURE 7 is a graphical representation of the motion and acceleration of the two slides through an angular rotation of the drive crank of 360.

In the embodiment of the invention illustrated in the drawing, a crank 1 is driven by a machine tool, the crank 1 for example rotating synchronously with a main shaft of a press. On the crankpin 5 of the crank 1 there is articulated a push rod 2, the other end of which is mounted in a bearing 4 on a lever 3 which increases the movement of the push rod 2. To this purpose one end of the lever 3 is mounted about a stationary lever bearing 6, while at the other end of the lever a link 8 is pivotally mounted in a bearing 7. The distance between the bearings 4 and 6 is smaller than the distance between the bearings 4 and 7, so that the movement of the link 8 is increased in the desired ratio in relation to the movement of the push rod 2. The link 8 is mounted on a pin 9 on a first slide 10, which is guided for sliding in the transport direction. When the crank 1 rotates the slide 10 therefore performs a reciprocating oscillatory movement.

This first slide 10 is guided by rollers 11 in a second slide 15, which in turn is guided for sliding movement in the transport direction on four

rails

24, 25, 26, and 27 disposed in a rectangle. In the centre of the slide 10 an

angle level

12, 16 is pivotally mounted about a bearing 17. The end of the arm 16 of the angle lever carries a bearing 18, on which a link 19 is articulated, the other end of said link being mounted about a pin 20 in the slide 15. The other end 12 of the angle lever carries a roller 21, which engages in a cam guide 22, the centre line of which is designated by 23. As long as the cam roller 21 rolls in a portion of the cam guide 22 which extends parallel to the rails 24 to 27 during the reciprocating movement of the slide 10, the

angle lever

12, 16 cannot turn about its bearing 17, so that the slide 10 is coupled rigidly to and integral in movement with the slide 15, and consequently the two

slides

10 and 15 move synchronously in the feed direction.

As can be seen from FIGURE 4, the two

lever arms

12, 16 of the bell crank or angle lever are displaced axially with respect to the bearing 17 and relative to one another, but are connected for joint rotation. FIGURE 5 illustrates how slide 15 is advanced in

tracks

24, 25, 26, 27. For this purpose, slide 15 is provided with

projections

54, 55, 56, 57 on its lateral surfaces, which projections surround, together with the lateral surfaces of the slide 15, the guide surfaces of the

tracks

24, 25, 26, 27.

Tracks

24, 25 are connected, by means of an intermediate connecting piece 51, with a stationary machine part 53;

tracks

26, 27 are connected, by means of an intermediate connecting piece 52, with the stationary machine part 53, which simultaneously supports guide 22. FIGURE 6 illustrates the carrier 37 which is guided by four columns 39, in the longitudinal direction of the columns and is driven by means of the two pins 34, which are moved by means of crank 31, illustrated in FIGURE 2, via the connecting line 32.

Towards the end of the swinging movement of the link 8, the rectilinear portion of the cam guide 22 ends and the cam guide becomes curved. This curve is so shaped that the cam roller gives rise to a rocking movement of the

angle lever

12, 16 about its bearing 17 and that the end of the lever 16 carrying the bearing 18 performs a movement oppositely to the movement of the slide 10. The cam path at the ends of the cam guide 22 is so selected that the movement of the lever end with the bearing 18 just compensates for the movement of the slide 10 in the feed direction, so that in the region of the curved portion of the cam guide 22 the slide 15 is stationary, that is to say it is stationar during a period of time during which the slide passes through the points of reversal of its swinging movement. The slide thus becomes stationary before the slide 10 reaches the reversal points of the swinging movement. The swinging movement of the second slide 15 is therefore shorter by the distance a than the swinging movement of the first slide 10.

On the slide 10 there is fastened a rack 28 meshing with a gear 29 which is fastened on a shaft 30 mounted in the slide 15. The circumference of the gear 29 amounts to twice a. When in the region of the reversal points of the slide 10 the two

slides

10 and 15 perform a movement relative to one another, the gear 29 first turns half a revolution in one direction corresponding to the displacement a and, when the slide 10 has moved out of its end position again, turns back half a revolution until the slide 15 is again coupled for movement to the slide 10 and moves synchronously along the feed direction.

On the shaft 30 there is fastened a crank which in each of the end positions of the slide 10 turns through 180". On the crankpin 33 of the crank 31 there is articulated a link 32 on which a connector 35 is suspended. The connector 35 engages in a bore 36 in a carrier 37. This bore 36 contains a spring 38, which is supported at one end on the inner end face of the bore 36 in the carrier 37 and at the other end against a shoulder on the connector 35.

The connector 35 extends through the entire bore 36 and at its end remote from the link 32 has an adjustable stop 43.

The carrier 37 has two pillars 39 which are guided for sliding movement perpendicularly to the direction of feed in corresponding bores 41 in the slide 15. At the top ends of the pillars 39 there is situated an adjustable stop nut 40, which bears against a stop surface 42 at the top end of the bore 41 in the slide 15. The carrier 37 can therefore follow a downward movement of the connector 35, which is driven by the crank 31, only until the stop 40 bears against the stop surface 42, The remainder of the downward movement of the connector 35 is absorbed by the spring 38. The carrier 37 consequently remains entirely stationary until the slide 15 comes to rest and as long as the vertical movement of the connector 35 is absorbed by the spring 38. The stop 43 then drives the carrier 37 upwards again. During this lifting movement the slide 15 is stationary, since the carrier 37 is moved only as long as the

slides

10 and 15 perform a movement relative to one another. If the curved portion of the cam 22 is so shaped that at the end of the curved portion of the cam adjoining the straight portion the movement of the bearing 18 does not yet completely compensate for the movement of the slide 10, the slide 15 still performs a movement while a relative movement between the

slide

10 and 15 is already taking place and thus the lifting movement is initiated. Through suitable choice of the curvature of the cam guide 22 it is therefore possible to select whether the slide 15 is to be stationary during the entire lifting movement or during only part of the lifting movement, or else, in exceptional cases, is to perform during the entire lifting movement a movement which is considerably retarded in relation to the slide 10. During a rotary movement of the crank 1 the carrier 37 is therefore lifted, advanced a determined distance in the feed direction, and lowered again at the end of this distance.

Gripping devices (not illustrated), for example tongs, for workpieces are provided on the carrier 37, and are adapted to grip the workpiece and lay it down again. If the oscillating movement of the slide 15 is not sufiicient to advance the workpiece the whole of the required distance, the carrier 37 may be made correspondingly longer and be provided with a plurality of gripping devices, the distance between which corresponds to the length of the oscillating movement of the slide 15, so that after the slide 15 has swung back the neighbouring gripper grips again a workpiece which has been laid down by the preceding gripper and advances it a distance corresponding to the amplitude of the oscillating movement of the slide 15.

The entire arrangement is driven by the link 8. Only small additional forces, which result from the additional acceleration and additional retardation of the slide 15, have to be supplied by the cam guide 22, while the length of the arm 12 of the angle lever makes it possible to ensure that the transverse forces applied by the cam guide 22 do not become excessively great.

FIGURE 7 illustrates the sinusoidal movement executed, for example, by slide 10 as drive crank 1 rotates through an angle of 360. The similarly sinusoidal acceleration of slide 10, which is merely phase-shifted relative to the motion of the slide, is represented below the representation of the movement. Similarly, the movement of slide 15, representing a substantially trapezoidal pattern, is also represented relative to an angular rotation of drive crank 1. Below the graph representing the movement of slide 15, the acceleration associated therewith is graphically represented.

I claim:

1. A drive for a feed device for workpieces which is useful particularly in conjunction with presses and which is driven by a rotating shaft with the aid of a cam guide and is stationary in the reversal points of a reciprocating movement, characterized in that the device comprises first and second slides guided for reciprocal motion in a transporting direction, said first slide being drivingly connected with a crank which imparts thereto an oscillating motion proportional to the rotary motion of the rotating shaft, said second slide being connected with said first slide by means of a coupling member, the con nection between said two slides being rigid except for swinging motion executed by said slides in the zone of the reversal points of their reciprocal motion, and further including a curved guide engaging said coupling member, moving same in the zone of the reversal points of the swinging movement and causing a relative motion between said two slides such that the second slide is slowed down with respect to said first slide in said zone.

2. A device according to claim 1, characterised in that a relative movement compensating the movement of the second slide (15) is derived from a part (21) moving with the first slide (10), of the coupling member which cooperates with a cam (22).

3. A device according to claim 2, characterised in that the coupling member (12, 16, 19) has an angle lever (12, 16) mounted in the first slide (10), the end of one arm (12) of said angle lever cooperating with the cam (22). in the region of the reversal points of the first slide (10) while its other arm (16) is connected to the second slide (15) by a link (19) extending approximately in the feed direction.

4. A device according to claim 3, characterised in that in the region between the reversal points of the second slide (15) the arm (12) of the angle lever (12, 16) is guided in a guide extending parallel to the feed direction.

5. A device according to claim 1, characterised in that between the crank (1) and the first slide (10) there is inserted a lever transmission system (3, 4, 6, 7) increasing the oscillating movement of the crank (1).

6. A device according to claim 1, characterised in that on a carrier (37) connected to the second slide (15) there are provided at least two grippers, which are disposed at a distance from one another which corresponds to the amplitude of the oscillating movement of the first slide (15).

7. A device according to claim 6, characterised in that from the movement performed by the two slides (10, 15) relative to one another there is derived a lifting movement, perpendicuarly to the feed movement, of a carrier (37 guided on the second slide (15).

8. A device according to claim 7, characterised in that the lifting movement is derived from a crank (31) which is driven in a reciprocating oscillatory movement by the relative movement of the two slides (10, 15).

9. A device according to claim 8, characterised in that in the movement phase in which the first slide (10) passes through its reversal points the lifting movement of the carrier (37) is limited by stops (40), and that the remainder of the lifting movement produced by the crank (31) is absorbed by a resilient connection (38).

References Cited UNITED STATES PATENTS,

Barton et a]. 74-4O Gzoon et a1. 74--40 Lehman 74-40 Morgan et al. 744O Roucka et a1. 74--40 Longfield 74-40 FRED c. MATTERN, 111., Primary Examiner W. S. RATLIFF, Assistant Examiner