PROCESS AND APPARATUS FOR FORGING ONE PIECE TRACK ROLLER RIM

Abstract: A process for forging a one piece track roller rim (31) comprising the steps of placing a hot metal billet (27) on a supporting block (1); closing a die (4) having two complementary half-shells (4a, 4b) which, when engaging each other, define a forging cavity (14) the inner shape of which corresponds to the outer surface of the track roller rim (31) to be formed; moving a hoop (7) to surround and lock the two half-shells (4a, 4b) closed; moving a cylindrical punch (8) into the forging cavity (14) to form an axial opening (29) in the billet (27) and forging the billet material into the inner shape of the forging cavity (14); removing the cylindrical punch (8) from the forged track roller rim (31); removing the track roller rim (31) from the supporting block (1). A machine is also provided to carry out the process.

Description: Description Process and Apparatus for Forging One Piece Track Roller Rim Technical Field The present invention relates to a process and apparatus for the forging of a hollow metal part, more particularly of a track roller rim for a track-type vehicle. Background Art The track roller rims of track-type vehicles generally consist of two complementary parts welded coaxially to each other. However, the present process used to produce the two piece track rollers is time consuming and costly. In fact, it requires that the ends of the parts to be attached to each other be machined prior to welding. Also, it necessitates considerable precaution to ensure a suitable alignment of the parts to be butt-welded to avoid the production of defective rollers. To solve such problems there have been attempts to produce one piece track roller rims from a single metal billet. Unfortunately, the solution proposed, which consisted in transforming the billet step by step using several interchangeable dies, is not fully satisfactory as it involves high investments and further requires fairly numerous and difficult handling operations to be performed by the personnel using such processes. Disclosure of the Invention The present invention aims at overcoming the various drawbacks discussed above, and it is therefore an object of the present invention to provide a process and apparatus for the forging of a hollow metal part, more particularly a one piece track roller rim for a track-type vehicle, which process is substantially characterized in that it comprises the steps of: placing a hot metal billet on a supporting block; closing a die having two complementary half-shells which, when brought together in a closed position, define forging cavity having a lower end closed by the supporting block, an open upper end, and an inner shape of which corresponds to the outer surface of the part to be produced; moving a hoop around the two half-shells so as to interlock them; moving a cylindrical punch into the forging cavity to form in the billet an axial opening with a bottom portion above the lower end of the extrusion cavity and to force the material of the billet against the inner surface of said extrusion cavity; removing the cylindrical punch from the extruded part; unlocking the two half-shells; moving the two half-shells apart; removing the extruded part resting on the supporting block; and punching out the bottom portion of the axial cavity in the extruded part. With this process, the track rollers and/or other hollow parts can now be produced from a single billet using a single die, thereby reducing the fabrication costs, improving the production rates and making the work easier for the personnel. In a preferred embodiment of the process, the two half-shells are brought together and are moved apart by being moved in opposite directions along a horizontal straight path; and the hoop that locks the two half-shells closed is removed therefrom by being moved vertically. In order to further increase the production rates, the hoop may be advantageously disposed around the two half-shells while the punch is being lowered, and removed therefrom while said punch is being raised. The present invention also relates to a apparatus for carrying out the process, said apparatus comprising a supporting block; a die having at least two complementary shells disposed on either side of the supporting block and movable in opposite directions from an open position, in which they are spaced apart, to a closed position in which they engage each other, said shells when in their closed position defining a cavity having one end closed by the supporting block, an open opposite end, and an inner shape which corresponds to the outer surface of the part to be produced; control means for moving the two half-shells in opposite directions along a straight path; a frame movable toward the supporting block from an inoperative position to a fully extended position; a hoop supported from the frame and so shaped as to surround the two half-shells in their closed position to lock them in the closed position when the frame is in an intermediate locking position between its extreme positions; a cylindrical punch mounted on the frame so as to project into the forging cavity when the frame is between its intermediate locking position and its fully extended position; and means for moving the frame between its inoperative and fully extended positions. The above as well as other features and objects of the machine according to the present invention will become apparent from the following description provided by way of example with references to the accompanying drawings. Brief Description of the Drawings Figure 1 is a schematic sectional and cutaway view of an apparatus according to the invention, with the components of said apparatus shown in their relevant position during the first step of the forming process; Figures 2 to 7 illustrate further steps of the forming process; Figure 8 is a schematic scaled down sectional view taken along line VIII-VIII of Figure 5; and Figure 9 is a schematic scaled down sectional view taken along line IX-IX of Figure 5. Best Mode In Carrying Out the Invention Referring now to the drawings, a cylindrical supporting block 1 is shown resting on a horizontal baseplate 2 which is integral with a fixed frame 3. A die 4 consists of two complementary half-shells 4a, 4b which are disposed on either side of the supporting block 1. Control means 5a, 5b are provided to move the half-shells 4a, 4b in opposite directions from an open position (as- shown by Figures 1 and 7) in which they are apart to a closed position (as shown by Figures 2 to 6 and 8) in which they engage each other and enclose the supporting block 1. A frame 6 is movable vertically above said supporting block from an uppermost position (as shown by Figures 1, 2, 6 and 7) . A rigid hoop 7 extending below the frame 6 is configured for closely surrounding the two half-shells 4a, 4b in their closed position, for solidly locking them in the closed position when the frame 6 is in an intermediate position as shown in Figures 3 to 5. A cylindrical punch 8 provided in the lower end of a column 9 projects vertically from the lower face of the frame 6. Means 10 is provided to move the frame 6 between its uppermost and lowermost positions, such means being for example hydraulic jacks. The half-shells 4a, 4b are movable in opposite directions between two straight guiding rails 11 (as shown on Figures 8 and 9) which are secured by means of screws 12 to the frame 3, on either side of the supporting block 1. The half-shells are respectively formed with two side brackets 13a, 13b projecting under the guiding rails 11 which keep the half-shells on the frame 3. The brackets are perpendicular to the half-shells on the frame 3. The brackets are perpendicular to the half-shells as is shown in Figure 8. In their closed position, the half-shells 4a, 4b have outer surfaces 22a,22b in the form of a truncated cone and defining inner surfaces forming and/or forging cavity 14 having its lower end closed by the supporting block 1 and its upper end in communication with a cylindrical prechamber 15 which is open at its upper portion. The forming cavity 14 and prechamber 15 extend coaxially with the punch 8, the inner surfaces of forming cavity 14 further having shape corresponding to the outer surface of the part to be produced. The control means 5a, 5b consist of two coaxial jacks having their cylinders 16a, 16b attached to the frame 3 and their piston rods 17a, 17b connected to the half-shells 4a, 4b. Referring more specifically to Figure 8, it can be seen that said jacks are equidistant from the guiding rails 11 and extend perpendicular to engage surfaces 18a, 18b of the half-shells. The hoop 7 is fastened to the lower end of vertical rods 19 slidably mounted on the frame 6. Such rods, of which only one is visible in the drawings, are distributed uniformly along the side wall of an imaginably cylinder, the axis of which is coincident with the axis of the hoop. The rods 19 are loosely secured to frame 6 by nuts 20 that are screwed on to their upper ends. To ensure proper locking of the half-shells, the inner surface 21 of the hoop 7 has a truncated shape corresponding to the truncated cone shape provided by the outer surfaces 22a, 22b of the half-shells 4 a, 4b, when the half-shells are in their closed position. The punch 8, in turn, is formed at its upper end with a cylindrically enlarged portion 23 which cooperates with the side surface of the prechamber 15 when the half-shells 4a,4b are in their closed positions to close the upper end of the forming cavity 14 when the frame 6 is in its lowermost position. Resilient members 24 are further interposed between the frame 6 and the hoop 7 so as to be compressed when the frame is between its intermediate locking position and its lowermost position. In the example illustrated, the resilient members 24 are formed by Belleville spring washers disposed in vertical tubes 25, 26 which are mounted in a telescopic manner between the hoop 7 and the frame 6. It should be noted that the telescopic tubes 25, 26 of which only one set is represented in the drawings, are angularly equidistant from one another as well as from the rods 19 supporting the hoop. Although the forging apparatus is shown and described in a generally vertical arrangement, it is to be understood that other orientations would be feasible. Industrial Applicability The operation of the apparatus according to the invention is described hereafter, assuming that the half-shells 4a, 4b are initially in their open position and the frame 6 is in its uppermost position. Firstly, a cylindrical steel billet 27 is placed on the supporting block 1, as shown in Figure 1. The billet used is slightly larger in volume than the volume of the track roller rim to be produced. It is heated to a temperature in the order of 1200°C. The jacks 5a, 5b are then actuated to move the half-shells 4a, 4b into engagement with each other, as illustrated on Figure 2. The billet 27 then extends into the forming cavity 14 and is slightly projecting into the prechamber 15. Next, the control means 10 is actuated to lower the frame 6. While the latter is moving from its uppermost position to its intermediate locking position as shown on Figure 3, the hoop 7 moves down around the half-shells 4a, 4b until its inner surface 21 comes into intimate contact with the outer surfaces 22a, 22b thereof solidly locking the half-shells into their engaged position. The punch 8 moves into the prechamber 15 at this time. As the frame 6 is moving from its intermediate position to its lowermost or fully extended position as shown on Figure 4, the Belleville spring washers 24 compress, maintaining the locking of the half-shells 4a, 4b by applying pressure on the hoop 7. The punch 8 penetrates into the billet 27 forcing the metal outwardly against the inner surface of the forming cavity 14 as frame 6 continues to move downward. When the frame 6 reaches its lowermost position as shown in Figure 4, the punch 8 will have formed an axial opening 29 with a relatively thin bottom portion 30 in the billet 27. The enlarged portion 23 is obstructing the upper end of the extrusion cavity 14 when the punch reaches this position. As the punch 8 is forced into the billet, the material of the billet is rearranged, taking the shape of the inner surface of the forming cavity 14 while forming the axial opening 29. The means 10 is now actuated reversibly so as to raise the frame 6. While the latter is moving away from its fully extended position, the punch 8 moves out of the cavity 29 of the forged part 31 made from the billet 27. It moves to the position represented in Figure 5, without the hoop 7 being driven upwardly. It should be noted here that the upward movement of the punch 8 from the cavity 29 is assisted by the Belleville spring washers 24. Then, as the frame 6 continues moving from the position shown in Figure 5 to the position shown in Figure 6, it drives with it the hoop 7, thus unlocking the half-shells 4a, 4b. Thereafter, the jacks 5a, 5b are actuated to bring the half-shells 4a, 4b to their open position as shown in Figure 7 and thus allows removal of the extruded part 31 from the extrusion cavity 14. The extruded part 31 is finally transferred to a punching station to cut out the bottom portion 30 of the cavity 29 in a well known manner. Then, the track roller needs only to be submitted to a conventional finish machining operation. The above described production cycle will of course be repeated to produce other track rollers. It stands out clearly from the foregoing that with the process and apparatus according to the present invention, one piece track roller rims can be produced more easily and quickly at a lower cost than with the processes and machines of the prior art. Although the apparatus is described as producing track rollers for track-type vehicles, it may be used without any limitations for producing other hollow metal parts. Other aspects, objects and advantages become apparent from study of the specification, drawings and appended claims.

Claims: Claims 1. A process for forging a one piece track roller rim from a billet of material, comprising the steps of: placing the billet (27) against a supporting block (1) ; closing a die (4) having at least two complementary shells (4a, 4b) which, when closed, define a cavity (14) having one end closed by the supporting block (1) , an open opposite end, and an inner surface with a shape corresponding to the outer surface of the track roller rim to be formed in the cavity; locking the shells (4a,4b) in their closed position; moving a cylindrical punch (8) into the cavity (14) to form an axial opening (29) in the billet (27) and to force the material against the inner surface of the cavity and form the track roller rim; removing the cylindrical punch (8) from the axial opening (29) ; unlocking the shells (4a, 4b) ; moving the shells (4a, 4b) apart; and removing the forward track roller rim (31) . 2. The process according to claim 1, wherein closing and opening of the shells (4a, 4b) is done by moving them in opposite directions along a straight path. 3. The process according to claim 1, wherein the hoop (7) locking the shells (4a, 4b) closed is moved in a straight path into and out of surrounding engagement with the shells. 4. The process according to.claim 1 or 3, wherein the hoop (7) surrounds the two half-shells (4a, 4b) locking them in their closed position while the punch (8) is being moved into the cavity, and it is removed as said punch is being moved out of said cavity. 5. An apparatus for forming a one piece hollow part from a billet of material comprising: a supporting block (1) ; a die (4) having at least two complementary shells (4, 4b) adjacent the supporting block (1) and movable between an open position in which they are spaced apart to a closed position in which they engage each other, said shells when in their closed position defining a cavity (14) having one end closed by the supporting block (1) , an open opposite end, and an inner surface having a shape corresponding to the outer surface of the part to be formed; control means (5a, 5b) for moving the shells (4a, 4b) between said positions along a straight path; a frame (6) mounted for movement with respect to the supporting block (1) and in a direction generally perpendicular to said path from an inoperative position to a moved position; a rigid hoop (7) supported on the frame (6) and configured to surround the shells (4a, 4b) in their closed position locking them in said closed position when the frame (6) is at a locking position intermediate its inoperative and moved positions; a cylindrical punch (8) mounted on the frame (6) to progressively project into the cavity (14) as the frame (6) moves from its intermediate locking position to its moved position; and means (10) for moving the frame (6) between its said positions. 6. The apparatus according to claim 6, wherein the shells (4a, 4b) are slidably mounted in parallel guiding rails (11) . 7. The apparatus according to claim 5, wherein the control means (5a, 5b) of the shells (4a, 4b) consist of two coaxial jacks. 8. The apparatus according to claim 5, wherein the extrusion cavity (14) is extended by a cylindrical prechamber (15) , the punch (8) being formed at one end with a cylindrical enlarged portion (23) which cooperates with the side surface of the prechamber (15) to close the open end of the extrusion cavity (14) when the frame (6) reaches its fully extended position. 9. The apparatus according to claim 5, wherein the outer surfaces (22a, 22b) of the shells (4a, 4b) and the inner surface (21) of the hoop (7) are truncated in shape and have the same dimensions when the shells are in their closed positions. 10. The apparatus according to claim 5, wherein the hoop (7) is fastened to the end of vertical rods (19) slidably mounted on the frame (6) . 11. The apparatus according to claim 5, wherein resilient members (24) are interposed between the frame (6) and the hoop (7) , so as to be compressed when the frame (6) is between its intermediate locking position and its fully extended position. 12. The apparatus according to claim 11, wherein the resilient members (24) are disposed in vertical tubes (25, 26) mounted in a telescopic manner between the hoop (7) and the frame (6) . 13. The apparatus according to claim 5 wherein the shells (4a, 46b) are two complementary half-shells.

Inventors: GARCIA RENE VINCENT HYACINTHE, GARCIA, RENE, VINCENT, HYACINTHE
Applicants: CATERPILLAR INC, CATERPILLAR INC.
Application year: 1988
Main classification: B21J5
IPC codes: B21J5, B21J13, B21K1, B21K23