US 2720800 A
Description (OCR text may contain errors)
Oct. 18, 1955 s. w. TAYLOR FORGING MANIPULATOR 2 Sheets-Sheet 1 Filed Nov. 27, 1951 llll United States Patent FORGING MANIPULATOR Sidney William Taylor, London, England, assignor to The Wellman Smith Owen Engineering Corporation Limited, London, England, a company of Great Britain Application November 27, 1951, Serial No. 258,458
Claims priority, application Great Britain November 30, 1950 2 Claims. (Cl. 78-96) This invention comprises improvements in or relating to furnace charging apparatus, manipulators for use in forging and other like apparatus of the kind (hereinafter termed the kind described), comprising a work carrying member, for example a peel, a carrier for such member, and a carrier support on which the carrier is mounted by means of one or more pivotal arms or levers, fluid pressure means being operative between the carrier and said arms or levers to raise and lower the carrier on the carrier support.
Such apparatus may be embodied in several forms. Thus it may be suspended overhead, it may run on rails, or it may be of the run-about type in which case it is mounted on wheels so that it can be moved to any desired position over a floor.
In various kinds of furnace charging apparatus, manipulators for use in forging and other like apparatus, means has heretofore been suggested for absorbing downward shock on the work carrying member arising, for example, when operating on forgings under a power hammer or press.
In apparatus of the kind described, it has been proposed to take up such downward shock on the work carrying member by cushioning apparatus in the form of an air vessel, or a spring loaded piston in an oil cylinder, connected in the supply line to the fluid pressure means by which the work carrying member is raised. Suggestion has also been made to apply compression of air in a receiver, caused by displacement of such a fluid pressure means under downward shock on the work carrying member, to bring about through a piston an increase in the pressure in the cylinder of fluid pressure power means for operating gripping means of the work carrying member, so that the shock while being taken up by the cushioning involved in the compression of the air in the receiver will also bring about increase of the gripping pressure on the work held by such gripping means.
These provisions in apparatus of the kind described have heretofore involved hydraulic losses, resulting in reduced resilience in the resistance to shock, when the apparatus is used in conjunction with such a rapidly displaceable device as a forging hammer. This has been because the cushioning of the shock, whether or not applied also to increase of the gripping pressure, involved movement of pressure fluid at high velocity along relatively small diameter pipes leading to the cushioning means from the fluid pressure means by which the work carrying member was raised. Under such conditions there is disadvantageous resistance to displacement of the pressure fluid through the pipes with consequent loss of efliciency.
It is an object of the present invention to provide improved means for taking up shock received by the work carrying member in a substantially vertical direction. A further object is to make improved provision for increasing, or improved means for maintaining, the gripping effect of the work carrying member on the work.
According to this invention apparatus of the kind described is characterised in that the pressure fluid means, operative between the carrier and the arms or levers on which the carrier is mounted, comprises a cylinder and piston combination which houses resilient means operative to exert control on the work carrying member.
According to another feature of this invention, apparatus of the kind described is characterised in that the fluid pressure means, operative between the carrier and the arms or levers on which the carrier is mounted, comprises a cylinder and piston combination of which the piston is made hollow and houses resilient means operative to exert control on the work carrying member.
The construction may be such that the resilient means will absorb shock exerted in the vertical direction on the work carrying member, or it may be such that the resilient means will be operative to increase the gripping pressure of the work carrying member on the work, or the construction may be such that both these effects are attainable.
In each of these cases, due to the resilient means being internal of the piston and cylinder combination, it is possible to dispense with pipe connections likely to cause the reduced resilience hereinbefore referred to. Thus, hydraulic contraction loss due to displacement of oil from the cylinder of the combination through the entrance to such pipe connections, friction loss along the pipes, and expansion loss through the exit opening of the pipes into a cushioning chamber are all eliminated.
In order to enable the invention to be readily understood several examples of construction, as applied to manipulators for use in forging, will now be described with reference to the accompanying drawings wherein:
Fig. 1 is a side elevation of a manipulator constructed in accordance with the present improvements, and
Figs. 2, 3 and 4 respectively are sectional plan views of difierent forms of the piston and cylinder combination.
In Fig. 1, the manipulator is for use in forging and is of the run-about type. It comprises a carrier support 1 mounted on wheels 2 to run over the floor. There may be two of these wheels at the front of the support 1 and a centrally disposed wheel or wheels at the rear. The drive is from a suitable engine or motor (not shown) mounted on the carrier support. The construction of this part of the apparatus is usual and well-known.
The peel 3 is supported by a carrier 4 which is mounted on the carrier support 1 by two parallel linkages, one on each side of the carrier. Only one of these linkages is shown but as the other is similar, only the one will be described. It is constituted by a pair of bell-crank levers 5, 6 respectively which have what may be termed vertical arms 7 and horizontal arms 8, the vertical arms 7 being connected together by a pivotal rod 9 so that the levers and rod constitute three of the links of such parallel linkage. Referring now to each linkage by similar reference numerals, the carrier 4 is pivotally mounted at 10, 11 on the angles of the two bell crank levers 5, 6 respectively of each linkage. The horizontal arms 8 of the bell crank levers 6 and 5 respectively of each linkage are connected pivotally to one arm of a lever or levers 12 mounted at 13 on the carrier support 1 and to a link 14 which is pivotally connected to one arm of a further bell crank lever 15 pivoted at 16 on the carrier support. Two fluid pressure operated apparatuses of which only one is shown, the other being similar, have their cylinders 17 fixed one on each side of the carrier support 1 and their pistons (not shown) are connected by connecting rods 18 pivotally to the other arms of the further bell crank levers 15. The other arm of the lever or levers 12 is or are pivotally connected to a part or parts 19 slidable in a cylinder or cylinders 20 against the action of V which is pivotally between the two parallel linkages, is shown in greater detail in Fig. 2. The cylinder 22 thereof is connected at 25 through a control valve (not shown) to a source of su 7 ply of fluid pressure and to exhaust. The piston 23 of the combination is made hollow and open at the cylinder end thereof and has a second piston 26'slidable therein adjacent that end. This second piston is prevented from leaving the hollow piston 23 by an abutment coliar 27 which determines the normal position of the piston 26. In effect, this piston 26 constitutes the operative end of the piston 23 though it is yieldable into the piston 23 for the purpose to be described. It will be seen that it is thus yieldable or slidable (for example to the position shown in Fig. 2) against the action of resilient means in the form of'a volute spring 28 which is slidable within the hollow piston 23. This volute spring acts between the second piston 26 and a spacer 29 which is also slidable within the hollow piston 23. Beyond this spacer, a further resilient means in the form of a reversely disposed volute spring 30 is provided. This further volute spring acts between the spacer 29 and a third piston. 31 of reduced dimensions slidable in a sleeve 32 within the opposite end of hollow piston 23. The outer end of this sleeve 32 is closed by a cap 33 to form a second cylinder. This second cylinder is connected at 34 and through a flexible pipe 35, Fig. 1, to fluid pressure operated apparatus 36 provided at the rear of the carrier 4 for operating the gripping jaws 37 of the peel 3.
In operation, when it is desired to raise the carrier 4 (and with it the peel 3), pressure fluid is admitted by appropriate adjustment of the aforesaid control valve to the cylinder 22 of the cylinder and piston combination 22, 23 connected between the carrier and the bell crank levers 6. This moves the bell crank levers 5, 6 about their pivotal connections 10, 11 on the carrier and thus the carrier rises parallel to itself. The volute springs 28 and 30 are constructed so that the piston 26 substantially does not yield from the abutment collar 27 during the raising of the carrier. On the other hand, their construction is such that the pressure fluid in the cylinder 32 at the other end of the hollow piston 23, which fluid is at a higher pressure than the pressure fluid in the cylinder 22, will hold the piston 31 back a little from the outer end of the cylinder 32 such as is indicated in Fig. 2.
Should it be desired to tilt the carrier 4 upwards at an angle the fluid pressure cylinders 17 on the carrier support 1 are supplied with pressure fluid so that only the bell crank levers 5 are moved (through the connecting rod 18, bell crank lever and link 14), and the carrier is tilted about the point of pivot at 38 of the bell crank levers 6 on the lever or levers 12, the other bell crank levers 6 remaining fixed relatively to the carrier. 7
Should the carrier 4 be subjected to shock in a vertical direction, such as when the apparatus is employed in a forging operation, then the carrier will tend to move downwards. As a result (the control valve aforesaid being closed), the cylinder 22 of the cylinder and piston combination 22,, 23,'Fig. 2, will move along the hollow piston 23 so that in effect the latter will move inwards into the cylinder 22. Since, however, the pressure fluid in the cylinder 22 is substantially incompressible this will cause the second piston 26 aforesaid to move backwards.
inside the hollow piston 23, away from the abutment collar 27, and as indicated in Fig. 2, against the action of its spring 28 so that the latter, and, through the slidbut this is not of importance.
able spacer 29, the spring 30, will absorb the shock.
'In turn, the second volute spring 30 will be forced against the third piston 31 which is subjected by way of the pipe 35 to the pressure of the pressure fluid in the cylinder 36 of the fluid pressure operated apparatus'for operating the gripping jaws 37 of the peel 3. The shock is thus being taken up by the springs 28 and 30, will therefore tend to move the third piston 31 outwards so as to increase the pressure in the cylinder 36 and cause the gripping jaws 37 to increase their pressure on the work held in the jaws. This is of advantage because, the pressure fluid not being elastic, an active grip may not maintained at all periods of operation on the work although the grips 37 are prevented from opening by the passive resistance of the fluid. An increase of pressure will, however, re-establish the grip, Further, if, for example, during forging under manipulation, and during working, the semi-plastic surface of the work contracts, a further closing of the grips37 will take place to keep the grip;
After the external restraining force of the forging hammer or press on the carrier 4' is removed on completion of the forging stroke the springs 28, 30 will return the second piston 26 to its initial position displacing pressure fluid from the interior of the hollow piston 23, thus moving the cylinder 22 and the bell crank levers 6, 5 and lifting the carrier and workpiece to their the piston 23, and 'will be communicated through that spring to the further volute spring 30, owing to the housing of the springs within the hollow piston and the yieldableness of the second piston 26 into the hollow piston 23 under the shock. Thus no connections, external of the cylinder and piston combination are required to enable the shockto be absorbed and hydraulic losses heretofore experienced are avoided. There would be a very small contraction loss due to the pressure fluid displacement from the cylinder -22 into the end of the hollow piston 23 past the abutment collar 27 There will be little, if any, movement of pressure fluid in the pipe 35 leading to the gripping means operating cylinder 36, because the fluid causing the gripping is locked in the cylinder 36, the grip'already having been taken and the control valve for this fluid closed. Altogether, therefore, the re- 7 of displacement of the work under vertical shock from such apparatus as a forging hammer.
According to a modification of the cylinder and piston combination abovedescribed, the spacer 29 may take the form of a fixed stop anchored in position in the hollow piston 23 by suitable means, so that the second and third pistons 26 and 31 will operate independently of each other. In that case the volute spring 28 would be designed to absorb the whole of the shock on the work carrying member 3, while the volute spring 30 would be constructed to maintain such pressure in the cylinder 36 through the piston 31 and pipe 35 as will enable the members, 37 -to secure appropriate grip on the work at all periods of operation thereon.
The piston and cylinder combination shown in Fig. 3 diflers from that illustrated in Fig. 2, in that'the resilient means within the combination is adapted only for maintaining appropriate grip on. the work. In this case,
In the form of piston and cylinder combination illustrated in Fig. 4, the aforesaid volute spring 30, piston 31 and sleeve 32 are dispensed with. The volute spring 28 retained operates between a fixed stop 43 and the slidable piston 26. This construction is designed to suit cases where it is desired to take up vertical shock on the work carrying member but not to increase the gripping pressure on the work.
It may be noted that Figures 2 to 4 illustrate a desirable versatility in the apparatus. That is to say, the cylinder and piston combination 22, 23 and parts to be disposed therein are employable in several ways to obtain desired eflects.
Parts shown in Figs. 3 and 4 which are not specifically referred to in connection with those figures but which are similar to those shown in Fig. 2 are indicated by similar reference numerals.
It will be understood that the volute springs used in the constructions described may be replaced by helical or other suitable type of springs. Moreover, other variations in the apparatus may be made without departing from the scope of the invention. For example, in Fig. 2, the two volute springs 28, 38 and the spacer 29 may be replaced by a single, though longer, spring bearing at its ends against the respective pistons 26, 32, or more than two springs could be used separated by appropriate spacers, the arrangement adopted depending on the size of the manipulator or the like and the rate of loading of the springs under the shock eflects.
The pivotal connection of the longitudinal arms of the bell crank levers 6 at 38 to the lever or levers 12 subjected to the opposition of a spring or springs in the cylinder or cylinders 20, is a convenient means whereby shock in a backward axial direction on the carrier may be taken up. However, the pivotal mounting at 38 may be on a fixed bracket or brackets on the carrier support 1 in which case, other suitable or known means may be adopted for absorbing backward axial shock eflects on the carrier as will be understood.
What I claim is:
1. In a furnace charging apparatus, a manipulator for use in forging, comprising a support, a carrier adjustably mounted on said support, a work carrying member mounted in said carrier and movable therewith, said work carrying member including means for gripping the work, levers pivotally connected to said carrier and said support for adjusting the position of said carrier with respect to said support, a first fluid pressure means operatively connected to said levers for adjusting the vertical position of said carrier on said support, and a second fluid pressure means mounted on said carrier for controlling said gripping means, said first fluid pressure means including a cylinder operatively connected to said lever means and adapted to receive motive fluid therein, a hollow piston slidably disposed in said cylinder and operatively connected to said carrier, a second piston mounted in said hollow piston and movable in response to pressure exerted by said motive fluid, resilient means mounted in said hollow piston in engagement with said second piston, said second piston responsive to relative movement of said cylinder and hollow piston when said work carrying member is subjected to vertical shock to exert a force on said resilient means, said resilient means thereby absorbing the shock as applied to said work carrying member, a third piston mounted in said hollow piston in engagement with said resilient means and communicating with said second fluid pressure means, said third piston moving in response to the force exerted on said resilient means thereby controlling the operation of said second fluid pressure means for increasing the gripping pressure on said work when the vertical force is applied thereto.
2. In a furnace charging apparatus, a manipulator for use in forging, comprising a support, a carrier adjustably mounted on said support, a work carrying member mounted in said carrier and movable therewith, said work carrying member including means for gripping the work, levers pivotally connected to said carrier and said support for adjusting the position of said carrier with respect to said support, a first fluid pressure means operatively connected to said levers for adjusting the vertical position of said carrier on said support, and a second fluid pressure means mounted on said carrier for controlling said gripping means, said first fluid pressure means including a cylinder operatively connected to said levers, a hollow piston connected to said carrier and slidably disposed in said cylinder for adjustng the position of said carrier and in an adapted position capable of movement in said cylinder when a vertical shock is applied to said work, a second piston slidably disposed in said hollow piston and moving in response to compressed fluid caused by relative shock inflicted movement of said cylinder and hollow piston, resilient means mounted in said cylinder adjacent said second piston and responsive to the movement of said second piston to absorb the vertical shock applied to said work, and means actuated by the movement of said second piston and associated with said second fluid pressure means for increasing the gripping pressure on the work when a vertical shock is applied thereto.
References Cited in the file of this patent UNITED STATES PATENTS 1,857,750 Wilbur May 10, 1932 2,257,546 Dienenthal et a1 Sept. 30, 1941 2,333,096 Dowty Nov. 2, 1943 2,345,572 Brosius Apr. 4, 1944 2,376,678 Foster May 22, 1945 2,379,388 Thornhill June 26, 1945 2,402,887 Greeley June 25, 1946 2,495,516 Foster Jan. 24, 1950