US3468154A

US3468154A - Manipulator for forging press

Info

Publication number: US3468154A
Application number: US485756A
Authority: US
Inventors: Albert Hertl
Original assignee: Hydraulik Fa GmbH
Current assignee: Hydraulik Fa GmbH; Hydraulik Firma GmbH
Priority date: 1964-09-01
Filing date: 1965-09-08
Publication date: 1969-09-23
Anticipated expiration: 1986-09-23
Also published as: CH440917A

Description

Sept. 23, 1969 A. HERTI.

MANIPULATYOR FOR FORGING PRESS 3 Sheets-Sheet 1 Filed Sept. 8, 1965 l W w 2 IN AMP/V70? HLBER T HERTL B YMVWOL W Sept. 23, 1969 A. HERTL 3,458,154

MANIPULATOR FOR FORGING PRESS Filed Sept. 8, 1965 3 Sheets-Sheet 2 WMWMM (ll MW Sept. 23, 1969 A. HERTL 3,468,154

MANIPULATOR FOR FORGING PRESS Filed Sept. 8, 1965 3 Sheets-Sheet S fims/vra/a HLBER T HERTL g7 M 12M United States Patent 3,468,154 MANIPULATOR FOR FORGING PRESS Albert Hertl, Duisburg, Germany, assignor to Firma Hydraulik G.m.b.H., Duisburg, Germany Filed Sept. 8, 1965, Ser. No. 485,756 Int. Cl. B21d 43/02 US. Cl. 72421 17 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for manipulating a workpiece relative to a forging press involves an undercarriage mounted for movement longitudinally relative to the forging press and supporting a tong holder movable longitudinally on the undercarriage and relative to the forging press. The undercarriage is provided with a stationary reference base which, during movement of the undercarriage relative to the forging press, remains fixed and stationary at a fixed distance from the forging press. This reference base serves for positioning the tong holder relative to the forging press and the work. Means are provided whereby the reference base may be stepwise adjusted, a preselected amount, longitudinally relative to the forging press and, responsive to this adjustment of the reference base, the tong holder is adjusted, relative to the undercarriage, a corresponding amount so that the tong holder remains at a fixed distance from the reference base. Also, and simultaneously with adjustment of the tong holder, the undercarriage is moved the preselected distance or amount so that the reference base remains fixed with respect to the forging press. The means for moving the tong holder exert a direct force on the latter which results in a reaction on driving means for the undercarriage, and this reaction is absorbed by an equal reaction force so that there is no resultant reaction on the undercarriage during relative adjustment of the tong holder. The undercarriage may be moved relative to the press either continuously or stepwise, and either regularly or irregularly, and in each case the reference base remains fixed relative to the forging press.

Means are also provided for adjusting the tong holder angularly through preselected angles of adjustment.

Background of the invention This invention relates to forging operations in which the workpiece is gripped in tongs movably mounted on an undercarriage which is movable longitudinally relative to a forging press. More particularly, the present invention is directed to a novel method of and apparatus for conjointly manipulating the undercarriage relative to the forging press and the workpiece relative to the undercarriage and to the forging press.

The mechanization or automation of forging apparatus necessitates the use of a manipulator for the workpiece, and which manipulator, in addition to the usual gripping or clamping means for the workpiece, should include lifting, lowering and tilting means for the workpiece gripping means. The manipulator also should include additional means to perform other auxiliary movements. A primary requisite of the manipulator is that it must be able to move the workpiece gripping means in accurate and exact increments of movement both longitudinally and angularly, with these increments being selectable as to amplitude. Such stepped movements are initiated by impulses transmitted from the control panel of the press or directly from the press.

The provision of a manipulator which will perform the above-mentioned functions persents relatively difiicult problems. Thus, in order to solve the diflicult problem of performing exact longitudinal steps of a preselected Patented Sept. 23, 1969 "ice amplitude, three conditions must be met. Furthermore, in order to solve the problem of performing exact and accurate angular displacement steps of a preselected amplitude, an additional condition must be met.

With respect to solving the problem of performing exactly measured longitudinal steps of a preselected amplitude, the conditions may be summarized as follows. In the first place, during longitudinal movement of the undercarriage relative to the press, the work gripping means must be maintained stationary relative to the forging press. Furthermore, during movement of the workpiece gripping means relative to the undercarriage, the reaction forces must be absorbed in such a manner that there is no resultant longitudinal movement of the undercarriage. The second condition which must be met is that the movement of the workpiece gripping means is, at all times, performed with reference to a point fixed relative to the forging press.

The third condition which must be met is that the movement of the undercarriage must be effected in exactly controllable longitudinal steps of a preselected amplitude and responsive to control impulses.

With respect to performing angular adjustments of the workpiece gripping means, the condition which must be met is that such rotation may be effected in exact angular increments of a preselected amplitude and either independently of the longitudinal movement of the workpiece gripping means or simultaneously with the longitudinal movement thereof.

An object of the present invention is to provide, in forging operations in which the workpiece is gripped in tongs movably mounted on an undercarriage which is movable longitudinally relative to a forging press, a method of manipulating the workpiece which completely fulfills the foregoing conditions.

Another object of the invention is to provide, in forging operations in which the workpiece is gripped in tongs movably mounted on an undercarriage which is movable longitudinally relative to a forging press, apparatus for manipulating the workpiece in a manner to completely fulfill each of the foregoing conditions.

A further object of the invention is to provide a forging manipulator comprising an undercarriage moving in a forging direction and a tong-holder also moving in the forging direction and mounted on roller, sliding, or swing bearings on the undercarriage, and which can be raised or lowered as well as moved in an angular direction, and in which the workpiece gripping tongs are mounted for angular adjustment.

A further object of the invention is to provide a method and apparatus of the mentioned type in which, during movement of the undercarriage in the longitudinal direction, the tong-holder is maintained stationary with respect to the forging press.

Yet another object of the invention is to provide a method and apparatus of the mentioned type in which during movement of the tongs relative to the undercarriage, the movement of the undercarriage, with respect to the forging press, is not altered by reaction forces.

A further object of the invention is to provide a manipulating apparatus of the type mentioned in which, on one hand, the tong-holder can be maintained stationary with respect to the forging press even if the undercarriage is moved longitudinally relative to the forging press at any speed and through any distance by driving means on the manipulator and, on the other hand, during longitudinal movement of the tong-holder by driving means on the manipulator, the resulting reaction forces do not effect any longitudinal movement of the undercarriage.

A still further object of the invention is to provide, in a workpiece manipulator for forging operations including a longitudinally movable undercarriage and gripping tongs movably mounted on the undercarriage in a tongholder, a drive means arranged in the undercarriage and which maintains the tongs stationary with respect to the forging press, or with respect to a reference point fixed relative to the press, even when the undercarriage is moving longitudinally.

A still further object of the invention is to provide, in a manipulator for manipulating workpieces with respect to a forging press, means for absorbing reaction forces due to movement of a tong-holder relative to an undercarriage so that movement of the undercarriage relative to the forging press is unaffected.

Still another object of the invention is to provide, in a manipulator for manipulating workpieces with respect to a forging press and including a longitudinally movable underframe and a tong holder movably mounted on the underframe, means providing a reference base for adjustment of the tong holder relative to the forging press, and which reference base is maintained at a fixed position relative to the forging press during adjustment of the tong holder.

An ancillary object of the invention is to provide for longitudinal movement of the tong holder relative to a stationary base section provided in the undercarriage, and which base section remains stationary even when the undercarriage moves longitudinally relative to the forging press.

Another object of the invention is to provide a drive for the undercarriage including a chain or rack fixed relative to the forging press and engaged by driving means on the undercarriage, and a second endless chain mounted on the undercarriage and connected, by transmission means, with the first mentioned chain or rack and constituting a reference base held stationary relative to the forging press.

Yet a further object of the invention is to provide a manipulating apparatus, for forging operations, of the mentioned type and in which movements of a tong holder under the influence of a control piston, in longitudinal steps of exactly predetermined amplitude, are effected responsive to external control impulses.

A further object of the invention is to provide a forging operations manipulator of the independent type which includes a controllable drive and a control device in the form of a control disk whose rotation is initiated by impulses either directly from the forging press or from the control panel therefor, and controls the stepping of a tong holder in such a manner that a control piston, and a tong-holder controlled thereby, are operated to perform longitudinal steps of a preselectable exact amplitude.

Yet another object of the invention is to provide, in a manipulating method or apparatus of the mentioned type, for imparting to tongs, mounted in a tong-holder for angular adjustment, angular displacements of a preselected exact amplitude, either independent of longitudinal movement of the tong-holder or simultaneously with the latter, with these angular displacements being effected responsive to external control pulses.

A further object of the invention is to provide, in a method and apparatus such as just mentioned, for using the tong-holder as a reference base for the angular displacement of the tongs, the tong-holder remaining stationary during angular displacement of the tongs.

For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a somewhat schematic side elevation view of a manipulator embodying the invention and operable to perform the method of the invention;

FIG. 2a is a longitudinal sectional view through a distribution slide valve for the drive of the tong-holder;

FIG. 2b is a longitudinal sectional view through a distribution slide valve controlling the drive of the undercarriage or frame;

FIG. 3 is a schematic illustration of a stepwise movable control device for operating a piston of a distribution slide valve;

FIG. 4 is a partial and incomplete elevation view corresponding to FIG. .3; and

FIG. 5 is a partially schematic elevation view of a rotary control device.

Referring to FIG. 1, a tong-holder 1 is swingably supported at points 2 on suspension bars 3 which are pivotally suspended from the free ends of levers 4. Levers 4 are angularly displaceably mounted on supports 6 on a frame 7, constituting an undercarriage, which is supported by wheels 8 movable along rails 9. Thereby, frame or undercarriage 7 is longitudinally displaceable relative to a forging press. By suitable actuator means, which have not been illustrated, the levers 4 may be selectively actuated to a position tong-holder 1 in either a horizontal or an inclined position, and at different elevations. In each position of tong-holder 1, driving elements 21a or 21b press against a ledge or abutment 5' on tong-holder 1. These elements constitute components of fluid pressure actuators and, in accordance with the direction of pressure fluid application, they can effect a longitudinal adjustment of tong-holder 1. The driving elements 21a and 21b are designed as cylinders which are displaceable relative to pistons 20a and 20b, respectively, which are fixed on frame 7. The manipulator has a self-contained source 10 of a pressure medium, and the pressure medium from source 10 supplies the working medium to all of the fluid pressure actuating means on the manipulator.

The problem posed in meeting the first condition mentioned above is solved, in accordance with the invention, by means including the cylinder-piston units 20-21 mounted on frame 7. The strokes of these units are suificient to effect, starting from the central or neutral position, substantially a maximum longitudinal step of the tongs either in a forward or in a reverse direction. The surfaces of the cylinder-piston units exposed to fluid pressure are of equal size, and their respective cylinder chambers 21a and 21b communicate with the connections 22a and 22b of a fluid pressure pump 22 mounted on frame 7 and arranged for operation in either direction. This pump 22 can operate either as a pump or generator or as a motor.

Pump 22, which can also idle, is driven, through the medium of a transmission means 23, by a driving wheel 24 rotatably mounted in frame or undercarriage 7. Driving wheel 24 is configured to engage a rack or chain 25 secured to the ground or floor to extend longitudinally relative to the forging press. Furthermore, transmission means 23 is arranged so that it can be disengaged.

In particular accordance with the invention, the speed reduction ratio from the rack or chain 25 to the pump 22 is so selected that the speed of frame or undercarriage 7, in the direction x, for example, produces an exactly equal speed of tong-holder 1 relative to the ground. This is effected by the admission of pressure fluid into cylinder 21a and exhaust of pressure fluid from cylinder 21b. Thus, tong-holder 1 moves in a direction opposite to the direction of movement of frame 7 so that the two movements cancel or balance each other. Tong-holder 1 thus remains stationary With respect to the ground or the forging press even though undercarriage or frame 7 is moved longitudinally. Thereby, the first part of the first condition mentioned above is met.

By supplying a metered amount of pressure fluid from source 10, through control 60, for example, into cylinder 21b, while simultaneously exhausting the same amount from cylinder 21a, tong-holder 1 is moved, relative to the ground or to the forging press, by a preselected amount in the direction b. At the start of this movement, piston 20b connected to frame 7 is accelerated in the direction y due to the pressure of the working medium supplied from source 10. The acceleration force is transmitted to the frame 7. However, at the same time, the pressure medium acts on pump 22 so that the latter acts as a motor.

Pump 22 thereby exerts a torque through transmission means 23 on driving wheel 24. Consequently, a force in the direction x is transmitted to rack or chain 25, which, being fixed, reacts with a reaction force in the direction y. This reaction force also acts on frame or undercarriage 7 and is exactly equal to the force transmitted from piston 20b to the frame and which is directed oppositely to the latter. Force and reaction force therefore cancel each other, so that the movement of frame 7 is unaffected by the stepping of tong holder 1. By the two expedients just mentioned, the first condition set forth above is fully met.

The second condition mentioned above is met, in accordance with the invention, by means including a double piston 61 (FIGS. 1 and 2) controlling a slide valve 60 in turn controlling the supply and exhaust of pressure fluid relative to cylinders 21a and 21b. Since slide valve 60 is connected with one of the driving elements of tongholder 1, illustrated, in the present example, as a cylinder 21a, slide valve 60, cylinders 21a and 21b, and thus also tong-holder 1 always follow the movement of double piston 61.

If this arrangement is to be mounted on any moving manipulator, such as the frame or undercarriage 7, and if the positioning of the tong-holder 1 with respect to the ground or to the forging press at an accurate location is to be assured after each movement of the tong-holder, double piston 61 must be fixed or stationary with respect to the ground or to the forging press. For this purpose, a reference base is provided in frame 7 and is always fixed or stationary with respect to the ground or with respect to the forging press during adjustment of the tongholder. Piston rod 62 can be moved, with respect to this reference base, in longitudinal steps of the preselected amplitude.

In accordance with the invention, such movement with respect to a fixed reference base is effected by providing an endless chain 32 trained over two

sprockets

30 and 31 rotatably mounted in frame 7. One of these sprockets is so connected, by means of a suitable transmission means, with the rack or chain 25 that the reduction ratio imparts, to endless chain 32, a circumferential or peripheral speed and motion which is exactly equal to the longitudinal speed and motion of frame 7. In the arrangement shown in FIG. 1, the transmission means 23 for driving pump 22 is also used to drive sprocket 30. It will be readily understood that, while

sprockets

30 and 31 are moved with frame 7, the upper run of chain 32 provides a reference base which is stationary with respect to the forging press for a period of time determined by the length of the upper run of chain 32.

By way of a particular example, carriage 40 is secured to the upper run of chain 32 so that it can move with this run in steps. By means of bar or rod 62 connected to carriage 40, the carriage effects the required or desired movement of double piston 61. However, a prerequisite is that undercarriage or frame 7 follows the stepped movement of carriage 40 to an extent such that carriage 40 always remains on the upper run of chain 32. In order to effect this, a second double piston 71 is moved by carriage 40 through the medium of piston rod 72, this double piston 71 being illustrated in longitudinal section in FIG. 2b. Piston 71 actuates a slide valve 70 secured on undercarriage or frame 7 and controlling the undercarriage. By the operation of slide valve 70, frame 7 is set in motion until slide valve 70 connected thereto has again assumed the illustrated closed or neutral balanced position with respect to piston 71. Manipulator frame or undercarriage 7 is thus forced to follow the movement of double piston 71.

By appropriate design of the drive of undercarriage 7, it is possible to provide for undercarriage 7 following the step-by-step movement of double piston 71 not in jerks or steps but rather in a smooth manner but at a variable speed. The length of the upper run of chain 32 is so dimensioned as to provide for the relative movement between frame 7 and carriage 40 at any time. The drive can be effected in a known manner. For example, and as illustrated, it can be effected by reversible fluid pressure motor 73 driving the carriage through transmission means.

Another objective of the invention relates to the stepwise movement of carriage 40 on the upper run of chain 32. Referring to FIG. 3, carriage 40 has operatively associated therewith a drive including a reversible fluid pressure motor 41. Motor 41, through a transmission means 42, drives a sprocket 43 rotatably mounted on carriage 40 and engaging the upper run of chain 32. Motor 41 is controlled by slide valve 44-46 which controls the supply of pressure fluid from source 10 to motor 41. Operation of distribution slide valve 44-46 is effected by a disengageable or interchangeable control disk 50 for the preselection of the desired amplitude of movement, and disk 50 is connected with sprocket 43 on carriage 40.

Referring to FIG. 4, control disk 50 is provided with radially displaceable plungers 51 each having a roller 52 at its outer end and each biased to a retracted inner position by a spring 53. Each roller plunger 51-53 has operatively associated therewith a lifter 54 mounted on the housing of carriage 40. Lifters 54 effect radially outward movement of plungers 51 to an extent such as to provide for a latch or catch 55, associated with each plunger, snapping into position behind the plunger and retaining the plunger in its extended position. The operation of lifters 54 is effected responsive to electrical pulses. The latched extended position of a plunger is indicated by the roller plunger 51-53 at the position a in FIG. 4.

A flap or operator 56 is hingedly or pivotally mounted on the housing of carriage 40 and, when this flap is swung outwardly, as indicated in FIG. 4, the double piston 44 of slide valve 45 is moved, against the bias of spring 46, to its closing position in which the supply of pressure fluid to motor 41, for either direction of operation, is interrupted.

Method of operation In the rest position of carriage 40, as shown in FIG. 4, double piston 44 is in the valve closing position. Consequently, both connections to motor 41 are at the same pressure so that there is no driving of gear wheel 43 and no movement of carriage 40 along the upper run of chain 32. As soon as a stepwise movement of the tongs 11 is to be effected, a pulse, supplied either directly from the forging press or from the control panel of the forging press, is applied to the lifter 54 at that one of the positions a, b, c x, y, 1 which corresponds to the amplitude of the stepwise movement to be effected. In response thereto, the roller plunger 51-53 associated with the particular lifter 54 is moved radially outwardly and retained in the extended position by the associated catch or latch 55. In FIG. 4, for example, this is represented by the roller plunger at the position d. At the same time, the electric pulse effects release of the catch 55 associated with the roller plunger 51-53 which is then at the point a and in extended position. This is effected by suitable means which have not been illustrated, and this latter roller plunger is moved radially inwardly to the retracted position. Thereby, double piston 44 is also moved out of its closing or balanced position under the bias of spring 46. Motor 41 is thus operated to rotate gear wheel 42, sprocket 43 and control disk 50 in the direction of the arrow until the extended plunger has moved from point at to point a, whereby flap or operator 56 is pivoted to a position to return double piston 44 to the closed position and thus interrupt the movement of motor 41. Due to the rotation of sprocket 43, carriage 40 is displaced by the preselected amplitude of movement longitudinally of the upper run of chain 32.

Due to this longitudinal movement or stepping of the carriage 40, double piston 61 is displaced. This causes tong-holder 1, connected with slide valve 60, to follow the movement of piston 61 until the latter is again in its closing position in slide valve 60. On the other hand, double piston 71 is simultaneously moved, through bar 72, in slide valve 70 so that the driving means 73, 74 effects movement of frame 7 in the direction of the stepping movement of the tongs.

To effect stepwise movement of carriage 40 in the opposite direction, the control may be switched to another flap or operator 56 associated with a second distributing slide valve 4446 and controlling reverse rotation of control disk 50, with the motor 41 being reversed in direction of operation by means of a suitable reversing slide valve.

The drive of the entire manipulator without stepwise movement of tong-holder 1 is effected by an additional hand control or remote control distributing slide valve connected to driving motor 73, this valve not being illustrated. Such control is effected after disengagement of the connections between sprocket 43 and gear 42 of carriage 40, as well as disengagement of the connection between pump 22 and transmission 23.

To clarify the operation of the independent manipulator of the invention, the sequence of operations will now be summarized. The undercarriage 7 moves in the forging direction substantially continuously and at any preselected speed. During such movement of the undercarriage 7, the portion of the upper run of chain 32 between the

sprockets

30 and 31, or between the vertical lines intersecting their pivots, provides a reference base which is stationary relative to the ground and the forging press during adjustment of the tongholder. This is true because the position of the

sprockets

30 and 31 constantly changes in the direction of movement on the carriage. The chain links on the lower run of chain 32 are thus being moved continuously to be added to the upper run, While the chain links of the upper run are continuously being taken off the opposite end of the upper run. The movement of underframe 7 may be either regular or, within certain limits, irregular. The main consideration is that the upper run of chain 32 always provides during adjustment of the tongholder, a steady reference position or base for the carriage 40 from which position the tongs 11 may be stepped in the forging direction. It is assumed that an ingot or the like is gripped by the tongs 11 for movement relative to the stationary press.

During a forging stroke, the press clamps the billet or the like supported in the tongs 11. The movement of the carriage 7 in a forging direction continues, while the upper run of chain 32 remains stationary, with respect to both the ground and the forging press, and thus forms a stationary reference base for the carriage 40. In spite of the continuously moving undercarriage 7, the carriage 40 is moved by one step and then remains stationary on the stationary reference base. This stepwise movement of carriage 40 is effected in the time between two successive forging strokes. Thus, both the upper run of chain 32 and the carriage 40 are maintained stationary, relative to the forging press, irrespective of the continued movement of the undercarriage 7. correspondingly, the tong holder 11 and the billet clamp therein are likewise maintained stationary. It should be noted that carriage 40 is locked against movement because of the application of equal fluid pressures to both sides of its driving member 41. After carriage 40 has performed one step stroke on the stationary reference base formed by the upper run of chain 32, those links of the upper run which have thus far formed the stationary reference base may be removed from the upper run since the stationary reference base is now formed by chain links which have been added, to the left end of the upper run of chain 32, by sprocket 30.

After the forging stroke of the press, the press tools open to release the billet or the like carried by the tongs 11 so that the billet can be shifted.

With the press tools now disengaged from the billet, a control command is given to the control arrangement 50 of the carriage 40'. As a result of this control command, and through the medium of the

means

44 and 45 of FIG. 4, the fluid motor 41 is energized and drives the sprocket 8 42 and 43. Carriage 40 is thus advanced through the desired control step with reference to the still stationary base provided by the upper run of chain 32, and in the forging direction. Undercarriage or frame 7 continues to travel on at the speed which it had at the beginning of the forging operation.

After completion of such step motion of the carriage 40 along the upper run of chain 32, carriage 40 is again fixedly positioned on the upper run of chain 32. Thereby, control piston '61 of the follower control, as shown in FIG. 2a, is fixed relative to ground. However, previously to this, this control piston has actuated the follower control. As carriage 40 is connected to the piston 61 and the piston rod 62, as well as to the piston 71 and the piston rods 72, the double piston 61 is displaced in control housing 60 during the previously mentioned stepping motion of carriage 40. Carriage 48 is fixedly connected with tong holder 1. Thus, the control impulse results in a follow-up motion of tong holder 1 with relation to the relative displacement of piston 61 until piston 61 reassumes its initial or neutral position in housing 60. This results in controlled flow of pressure medium relative to the tong holder shifting cylinders 21a and 21b. A proportioned quantity of pressure medium flows into one cylinder 21b and, at the same time, the same quantity of pressure medium is exhausted from the other cylinder 21a. Tong holder 1 is thus moved in the forging direction through a preselected distance corresponding to the stepping of the carriage 40, and then remains stationary relative to the press. Thus, the billet clamped in the tongs 11 is also held stationary for the succeeding forging operation.

However, simultaneously with movement of carriage 40, control piston 71, shown in FIG. 212, has been moved relative to its cylinder 70. This movement effects an operation of the fluid motor 73 which, through the intermediate gear 74, operates the drive of under frame 7 to move the under frame in the forging direction. The upper run of chain 32 still remains stationary relative to the forging press, and thus constitutes an again stationary reference base for the next shifting of the tongs, after completion of the new forging step and opening of the forging press tools.

Angular displacement of tongs 11 in a stepwise manner is effected by the means shown in FIG. 5. This means is a control device acting in the same way as the control device for the longitudinal stepping of carriage 40. Referring to FIG. 5, a reversible fluid pressure motor 81 is secured on tong-holder 1 and drives a gear 83, connected with tongs 11, through a transmission means 82. A con trol disk 90 is disengageably connected with gear 83 and is provided with roller plungers 91 in the same manner as described with respect to the parts 51-55 shown in FIG. 4. In a like manner plungers 91 act on a flap or operator 96 actuating double piston 84 in a distributing slide valve 85 similar to the parts 44-46 of FIG. 4. This effects rotation of driving motor 81 by pressure fluid from source 10, and tongs 11 are turned through the desired angle as soon as an impulse is transmitted either from the control panel of the press or directly from the press.

FIG. 5 shows the parts in a position in which the roller plunger aligned with the double piston 84 of slide valve 85 has been retracted to its innermost position, and a roller plunger displaced at an angle of 45 has been extended, so that rotation of the tongs is effected in a direction of the arrow. As soon as the now extended roller plunger is aligned with double piston 84, thus actuating flap or operator 96 and moving double piston 84 in slide valve 85 to the closing position, the supply of fluid pressure to motor 81 is interrupted and the rotary displacement of tongs 11 has been completed.

What is claimed is:

1. Apparatus for manipulating a workpiece relative to a forging press comprising, in combination, a carriage movable longitudinally relative to the forging press; a tong-holder mounted on said carriage for movement relative thereto; tongs on said tong-holder for gripping the workpiece; means mounting said tongs for angular displacement relative to said tong-holder; a source of pressure fluid on said carriage; a fluid pressure motor operable, when activated, to angularly displace said mounting means; .a balanced slide valve connecting said fluid pressure motor to said source of pressure fluid; means normally biasing said valve to an unbalanced position for supplying fluid to said fluid pressure motor to activate the same for rotation in a selected direction; a control disk .angularly displaceable with said mounting means; an operator for said valve disposed at a preselected angular position with respect to said control disk and effective, when operated, to move said valve to the balanced position to interrupt activation of said fluid pressure motors; a plurality of radially displaceable actuators mounted on said control disk at equal angular spacings therearound; means biasing each actuator to the radially retracted position; extender means each operatively associated with a respective actuator to radially extend the same; each extended actuator, when at said selected angular position, engaging said operator to move said valve to the balanced position to interrupt activation of said fluid pressure motor; signal responsive means operable to effect radial retraction of the actuator then at said selected angular position and to effect extension of another actuator spaced an angular distance from said preselected angular position equal to the desired displacement of said tongs; the radial retraction of the actuator then at said selected angular position effecting operation of said valve to activate said fluid pressure motor to rotate said mounting means and said disk in a direction to advance the then extended actuator to said selected angular position to engage said operator to restore said valve to the balanced position to interrupt activation of said fluid pressure motor.

2. In forging operations in which the workpiece is gripped in tongs movably mounted on an undercarriage of an independent manipulator which is movable longitudinally in the forging direction relative to a forging press and independently of the forging press, the method of moving the tongs holding the workpiece stepwise longitudinally of the forging direction comprising the steps of providing, on the undercarriage, a reference base for movement of the tongs; during forging operations, moving the undercarriage at a preselected speed relative to the press, in the forging direction; during a forging stroke of the forging press, maintaining a reference base on the moving undercarriage stationary relative to the press, and maintaining the tongs stationary relative to this stationary reference base, whereby to maintain the tongs stationary relative to the press; following each forging stroke of the forging press, and while the undercarriage continues to move in the forging direction, moving the tongs, in the forging direction and on the then still stationary reference base, by one step of a preselected length, and then maintaining the tongs stationary on the reference base; and then, during the succeeding forging stroke of the forging press, maintaining the tongs stationary on a reference base on the undercarriage which is then also maintained stationary relative to the press during movement of the undercarriage.

3. In forging operations, the method of manipulating a workpiece, as claimed in claim 2, including the steps of moving the tongs, by direct force, relative to the undercarriage; and balancing the resultant equal reaction forces on the undercarriage by applying, to the undercarriage, a force equal to such reaction force in an opposition to the latter; whereby to neutralize the acceleration forces on the undercarriage.

4. In forging operations, the method claimed in claim 2, including continuing the movement of the undercarriage in the forging direction during such succeeding forging stroke of the forging press.

5. In forging operations, the method claimed in claim 2, including, during stepping of the tongs in the forging direction from the stationary reference base, moving the tongs, by direct force, relative to the undercarriage; and

balancing the resultant equal reaction force on the undercarriage by applying, to the undercarriage, a force equal to such reaction force and in opposition to the latter; whereby to neutralize the acceleration forces on the undercarriage to maintain the movement of the undercarriage unaffected by the acceleration forces.

6. In forging operations, the method claimed in claim 2, including the steps of, and simultaneously with adjustment of the tongs relative to the undercarriage in one direction, moving the undercarriage in the same direction an equal amount to maintain the reference base stationary relative to the press.

7. Apparatus for manipulating a workpiece relative to a forging press comprising, in combination, an independent manipulator including an undercarriage mounted for longitudinal movement in the forging direction relative to the forging press and independently to the forging press; driving means on said undercarriage operable to move said undercarriage at a preselected speed relative to the press in the forging direction; a tong holder movably mounted on said undercarriage; tongs movably mounted on said tong holder to grip the workpiece; means on said undercarriage providing a reference base stationary relative to the forging press during a forging stroke; means operatively associated with said undercarriage and with said reference base and operable, responsive to movement of said undercarriage relative to the press, to move said reference base providing means correspondingly relative to the press during a forging stroke; shifting means selectively operable to move said tong holder after a forging stroke, in the forging direction and on said stationary reference base, by one step of a preselected distance; and means operable, responsive to operation of said shifting means, to move said undercarriage an equal distance in the same direction as the direction of movement of said tong holder.

-8. Apparatus for manipulating a workpiece relative to a forging press, as claimed in claim 7, including means operable, responsive to operation of said shifting means exerting a direct force on said tong-holder to shift said tong-holder longitudinally relative to said reference base, with resulting and equal reaction transmitted to said undercarriage, to .apply a force to said undercarriage equal to said direct force and in opposition to said reaction on said undercarriage.

9. Apparatus for manipulating workpieces relative to a forging press, as claimed in claim 7, including fluid pressure actuator means operatively interconnecting said tongholder and said undercarriage and selectively operable to shift said tong-holder longitudinally relative to said undercarriage; a reversible fluid pressure pump-motor mounted on said undercarriage; a closed pressure fluid circuit interconnecting said pump-motor and said fluid pressure actuator means; said driving means being operable, responsive to movement of said undercarriage longitudinally with respect to the forging press, to operate said pumpmotor to energize said fluid pressure actuator means to move said reference base and said tong-holder conjointly longitudinally relative to the carriage and in a direction and amount to maintain said reference base and said tongholder stationary relative to the forging press.

10. Apparatus for manipulating a workpiece relative to a forging press, as claimed in claim 7, comprising means, including transmission means coupled with said driving means, operable, responsive to movement of said undercarriage in one direction relative to the press, to move said tong-holder in the opposite direction relative to the press and to the same extent, to maintain said tong-holder stationary longitudinally relative to the forging press.

11. Apparatus for manipulating a workpiece relative to a forging press, as claimed in claim 7, including actuator means selectively operable to shift said tong holder longitudinally relative to said reference base; driving mechanism, including a rotary transmission member, operatively associated with said driving means; a pair of sprockets rotatably mounted in longitudinally spaced relation on said undercarriage; a chain engaged over said sprockets and having an upper run, said upper run constituting said reference base; and means connecting at least one of said sprockets to said rotary transmission member and effective, responsive to longitudinal movement in a selected direction of said undercarriage relative to the forging press, to drive said chain to maintain said upper run stationary in space and fixed relative to the forging press.

12. Apparatus for manipulating workpieces relative to a forging press, as claimed in claim 9, including means selectively operable to activate said fluid pressure actuator means to shift said tong-holder longitudinally relative to said undercarriage, thereby causing a corresponding reaction tending to move said undercarriage; said fluid pressure actuator means, during such shifting movement, operating said pump-motor as a motor through said closed pressure fluid circuit; and transmission means included in said driving mechanism operable, responsive to operation of said pump-motor as a motor, to exert on said undercarriage a force equal and opposite to said reaction to maintain said undercarriage stationary.

13. Apparatus for manipulating a workpiece relative to a forging press, as claimed in claim 11, including a control device selectively settable to control the degree of shifting of said tong-holder longitudinally relative to said base, and further including a member engaged with and shiftable along the upper run of said chain by an amount corresponding to the desired amplitude of shifting of said tong-holder; first and second elements connecting said member to said first and second control means, respectively, said first element, responsive to said shifting of said member, operating said first control means to activate said actuator means to shift said tong-holder by the preset amount; said second element, responsive to shifting of said member, activating said second control means to operate said driving device to move said undercarriage in the direction of the shifting movement of said tong-holder and through a distance equal to the distance that said tong-holder is shifted; said driving mechanism, including said rotary transmission means, thereby operating said chain to displace the upper run of said chain longitudinally in a direction and to .an extent such as to maintain said member fixed longitudinally relative to the forging press.

14. Apparatus for manipulating a workpiece relative to a forging press, as claimed in claim 13, in which said actuator means comprises fluid pressure actuator means; said first and second control means comprising slide valves each having a piston slidable therein in a casing secured to said undercarriage; and a source of pressure fluid mounted on said undercarriage and connected to said slide valves; said driving device comprising a fluid pressure motor; said elements comprising piston rods rigidly connected to said member and to the pistons of said slide valves.

15. Apparatus for manipulating a workpiece relative to a forging press, as claimed in claim 14, in which said presettable control device comprises a rotatable disk, a sprocket secured to said disk for rotation therewith and engaged with the upper run of said chain; a second fluid pressure motor operable, when energized, to rotate said disk and said last-named sprocket; a balanced slide valve, normally biased to the open position, controlling an application of fluid pressure to said second fluid pressure motor; a normally ineffective valve operator operatively associated with said last-named slide valve and disposed at a selected angular position adjacent the periphery of said disk; a plurality of radially displaceable actuators arranged at equal angular spacings around the disk; means biasing said radially displaceable actuators to the radially retracted position; each radially displaceable actuator, when at said selected angular position and when radially extended, engaging said operator to move said last-named slide to the balanced position to interrupt operation of said last-named fluid pressure motor; actuator means each associated with the respective radially displaceable actuator; signal responsive means operable to energize an ac.- tuator extending means located at an angular position, relative to said selected angular position, corresponding to the desired degree of shifting of said tong-holder and simultaneously to eifect retraction of the radially displace- .able actuator then at said selected angular position to release said last-named slide valve to supply pressure fluid to said second fluid pressure motor to rotate said disk and said sprocket in a direction to engage the then extended radially displaceable actuator with said valve operator; the then extended radially displaceable actuator, when reaching said selected angular position, engaging said operator to restore said last-named slide valve to the neutral position to interrupt operation of said second fluid pressure motor.

16. Apparatus for manipulating a workpiece relative to a forging press, as claimed in claim 15, including spring means associated with each radially displaceable actuator and effective to bias the same to the retracted position; and latch means each associated with a respective radially displaceable actuator and effective, upon extension of the selected radially displaceable actuator, to latch the latter in the extended position; said signal responsive means releasing the latch means associated with the radially displaceable actuator then at said selected angular position.

17. Apparatus for manipulating a workpiece relative to a forging press, as claimed in claim 1, including driving means on said carriage; shifting means operable to move the tong-holder longitudinally relative to a reference base on said carriage; means, including said driving means, operable, responsive to movement of said carriage a preselected amount in one direction relative to the press, to maintain said reference base stationary relative to the press and to control said shifting means to maintain said tong-holder stationary relative to said reference base, to maintain the tongs longitudinally stationary relative to the press.

References Cited UNITED STATES PATENTS 3,267,708 8/1966 Sims et al. 72421 X 3,349,601 10/ 1967 Burrows 72-421 X 3,125,053 3/1964 Mitchell 72-45 3 3,274,819 9/ 1966 Knowles 7242l CHARLES W. LANHAM, Primary Examiner E. SUTTON, Assistant Examiner