Patent Application
20070151318
1. Field of the Invention
The invention relates to a forging machine, more particularly to an improvement relating to a workpiece holding clamp mechanism of a forging machine.
2. Description of the Related Art
Generally, forgings, such as screws and nuts are manufactured by feeding a rod-like material from a roll of raw material into a forging machine, where the material is straightened and cut into workpieces with a predetermined length. The workpieces are clamped and transported to a plurality of punching units to undergo a series of punching and forging processes, and the resulting semi-products are transported to next stations for subsequent operations, such as tapping, thread forming, etc.
Referring to
The number of the roller frames 13 corresponds to that of the workpiece holding clamp mechanisms 2. The workpiece holding clamp mechanisms 2 are mounted on the slide plate 15 and each include a transmission shaft 21 extending through the slide plate 15 and projecting leftwards and rightwards, a swing arm 22 mounted on the left end of the transmission shaft 21, a first clamp arm 23 mounted on the right end of the transmission shaft 21, a driven shaft 24 parallel to the transmission shaft 21 and extending through the slide plate 15, two meshing sector gears 25 mounted respectively on the transmission and driven shafts 21, 24, a second clamp arm 26 mounted on the driven shaft 24 proximate to the first clamp arm 23, first and second clamp jaws 27, 27′ connected respectively to the first and second clamp arms 23, 26, and a returning spring 28 mounted on the slide plate 15 to bias the first clamp arm 23.
When the cam wheel 14 drives the roller frame 13 to swing, the roller frame 13 pushes the swing arm 22 so that the transmission shaft 21 rotates itself and further drives the driven shaft 24 to rotate in an opposite direction. The first and second clamp arms 23, 26 are therefore actuated to swing in opposite directions so that the first and second clamp jaws 27, 27′ are opened and moved away from each other, thereby compressing the returning spring 28. When the cam wheel 14 stops camming the roller frame 13, the returning spring 28 returns to its original position and biases the first clamp arm 23 and the related components to swing so that the first and second clamp jaws 27, 27′ are closed.
Referring to
Like the swing arm 22, the first clamp arm 23 also includes a sleeve part 231, first and second prongs 233, 233′, a key 235, and locking screws 236. The connection between the first clamp arm 23 and the transmission shaft 21 is similar to that of the swing arm 22 and the transmission shaft 21. However, the first clamp arm 23 has a passive extension part 237 to be biased by the returning spring 28, instead of having the lugs 224 of the swing arm 22. In addition, a lower extension part 238 projects from the sleeve part 231 to connect with the first clamp jaw 27.
Since the swing arm 22 and the first clamp arm 23 are mounted on the transmission shaft 21 while interacting with the roller frame 13 and the returning spring 28, respectively, the swing arm 22 and the first clamp arm 23 are subjected to torsion forces during the forging operation. Generally, stresses due to such torsion forces are concentrated at the juncture of each sleeve part 222, 232 and the corresponding prong 223, 223′ , 233, 233′ so that cracks can easily occur in the swing arm 22 and the first clamp arm 23. Such cracks might affect adversely the accuracy of the operation of the swing arm 22 and the first clamp arm 23. Thus, the life of the swing arm 22 and the first clamp arm 23 is usually short, and frequent replacement thereof is necessary, thereby reducing the production efficiency and increasing the manufacturing costs.
An object of the present invention is to provide a workpiece holding clamp mechanism with a robust construction so as to prolong the life of the workpiece holding clamp mechanism.
According to one aspect of the present invention, a workpiece holding clamp mechanism comprises: first and second clamp arms which have first and second clamp jaws, respectively, and which are turnable to open or close the first and second clamp jaws; and a transmission shaft having a key groove. The first clamp arm is mounted on the transmission shaft, and includes a sleeve part sleeved onto the transmission shaft proximate to the key groove and having a shaft receiving hole, a first prong extending axially from the sleeve part and having a shaft receiving recess which extends axially from the shaft receiving hole, a second prong extending axially from the sleeve part and spaced apart transversely from the transmission shaft, and a connection part bridging the first and second prongs. The first and second prongs cooperate with the sleeve part and the connection part to confine a receiving space which is aligned with the key groove. The first clamp arm further includes a key disposed within the receiving space and inserted into the key groove, and a fastener that extends through the second prong and locks the key in the key groove.
According to another aspect of the present invention, a workpiece holding clamp mechanism comprises: a transmission shaft having a first key groove; a driven shaft parallel to and driven by the transmission shaft; a swing arm mounted on the transmission shaft; a first clamp arm mounted on the transmission shaft opposite to the swing arm; and a second clamp arm mounted on the driven shaft.
The swing arm includes a sleeve part sleeved onto the transmission shaft proximate to the first key groove and having a shaft receiving hole, a first prong extending axially from the sleeve part and having a shaft receiving recess which extends axially from the shaft receiving hole, a second prong extending axially from the sleeve part and spaced apart transversely from the transmission shaft, and a connection part bridging the first and second prongs. The first and second prongs cooperate with the sleeve part and the connection part to confine a receiving space which is aligned with the first key groove. The swing arm further has a key disposed within the receiving space and inserted into the first key groove, and a fastener that extends through the second prong and locks the key in the first key groove.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:
Referring to
The transmission shaft 4 extends through the slide plate 15 and includes two end portions on two opposite sides of the slide plate 15, and first and second key grooves 42, 42′ respectively formed in the end portions.
The swing arm 5 is mounted on one of the end portions of the transmission shaft 4 and is actuated by a roller frame (shown at 13 in
The present invention resides in a connection part 513 that bridges the first and second prongs 512, 512′ and that is spaced apart from the sleeve part 51. Preferably, the connection part 513 is formed as one piece with the sleeve part 51 and the first and second prongs 512, 512′. The key 52 is disposed within a receiving space 514 which is defined by the sleeve part 51, the first and second prongs 512, 512′, and the connection part 513 and which is aligned with the first key groove 42. The key 52 is further inserted into the first key groove 42 and is locked therein by two fasteners, i.e. locking screws 53 which extend threadedly through the second prong 512′ and which have ends abutting against the key 52.
The sleeve part 51 further has two spaced apart lugs 515 which project radially from the sleeve part 51, and a roller 54 mounted rotatably between the lugs 515. The roller 54 is provided to abut against the roller frame 13 (see
The first clamp arm 6 is mounted on the other end portion of the transmission shaft 4 and has a construction substantially similar to that of the swing arm 5. In particular, the first clamp arm 6 includes a sleeve part 61 disposed around the transmission shaft 4 and having a shaft receiving hole (not shown) for receiving the transmission shaft 4, a first prong 612 extending axially from the sleeve part 61 and having a shaft receiving recess 6121 of substantially semi-circular cross-section extending axially from the shaft receiving hole to receive one side of the transmission shaft 4, a second prong 612′ extending axially from the sleeve part 51 and spaced apart from the transmission shaft 4, and a key 62.
The present invention further resides in a connection part 613 that bridges the first and second prongs 612, 612′ and that is spaced apart from the sleeve part 61. Preferably, the connection part 613 is formed as one piece with the sleeve part 61, and the first and second prongs 612, 612′. The key 62 is disposed within a receiving space 614 which is defined by the sleeve part 61, the first and second prongs 612, 612′, and the connection part 613 and which is aligned with the second key groove 42′. The key 6 is further inserted into the second key groove 42′ and is locked therein by two fasteners, i.e. locking screws 63 which extend threadedly through the second prong 612′ and which have ends abutting against the key 62. As a result, the first clamp arm 6 is fastened firmly to the transmission shaft 4.
The first clamp arm 6 does not have any components corresponding to the lugs 515 and the roller 54 of the swing arm 5. Rather, the first clamp arm 6 is provided with a lower extension 615 which extends downward from the sleeve part 61 to connect with the first clamp jaw (see numeral 27 in
The second clamp arm 7 is rotated by the driven shaft 8 which rotates in a direction opposite to that of the transmission shaft 4 like the second clamp arm 26 of the prior art described hereinbefore.
When the swing arm 5 is actuated to rotate the transmission shaft 4, the first and second clamp arms 6 and 7 are turned in opposite direction so that the first and second clamp jaws attached thereto are closed. When the swing arm 5 is not actuated, the upper extension 616 is moved by the returning spring (see
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
