1. Field of the Invention
The present invention relates to a press device. More particularly, the present invention relates to an arrangement for slidably mounting a slide cam to a slide cam base which allows little unwanted deflection, and which provides sufficient biasing force to the slide cam over the entire stroke length of the slide cam.
2. Description of the Background Art
As shown in FIGS. 13 and 14, a prior art press device includes a slide cam base, a slide cam guided by the slide cam base, a machining member such as a punch mounted to the slide cam, a biasing member provided between the slide cam base and the slide cam for biasing the slide cam, and an actuating cam for abutting with the slide cam to drive the slide cam.
In FIGS. 13 and 14, the press device more specifically includes a slide cam base 102 having a quadrangular-section guide member 101 formed at the head thereof, a slide cam 103 guided by the slide cam base 102, a machining member such as a punch 109 mounted to the slide cam 103, a coil spring 104 provided between the slide cam base 102 and the slide cam 103 for biasing the slide cam 103, and an actuating cam 105 for abutting the slide cam 103 to drive the slide cam 103. The quadrangular-section guide member 101 of the slide cam base 102 abuts against a wear plate 106 of the slide cam and is held by guide plates 107, and the guide plates 107 are threadably tightened to the slide cam 103 with many bolts 108.
After a work W has been placed on a supporting member 111 of a lower die 114 in which a die bush 110 was embedded, when an upper die 115 lowers, the wedge-shaped slide cam 103 is moved toward the work W between the slide cam base 102 and the actuating cam 105. Then, when the upper die 115 begins to rise after a machining operation has been completed, the slide cam 103 is moved backward due to a biasing force of the coil spring 104 to its original position.
A stripper plate 112 is biased by a pressurizing rubber 113.
In such press devices as described above, a large problem is not present where the dimension thereof in the lateral direction as shown in FIG. 14 (in the horizontal direction in the figure) is short. However, where the length of the slide cam 103 in the lateral direction becomes a value, for example, about 300 mm or more, the guide member 101 of the slide cam base 102 is held insufficiently with the wear plate 106 and the guide plate 107 mounted to the slide cam 103, so that a noticeable deflection occurs so that pressing with a high precision is hard to perform. Further, machining of the guide member 101, the wear plate 106 and the guide plate 107 requires a longer time, thereby making press devices expensive.
Also, in maintaining the prior art press devices, dismounting the slide cam 103 from the slide cam base 102 requires many bolts 108 to be loosened in order to dismount the guide plate 107, so that maintaining the press devices has taken a longer time.
Further, the output from the coil spring 104 used as a biasing force of the slide cam 103 becomes larger depending on the compressed length and when the compressed length of the coil spring 104 is short, the output becomes small, so that the coil spring 104 may not positively move the slide cam 103 back to the original position. A coil spring with an ordinary size is very difficult to have the compressed length of about 150 mm and thus cannot give a stroke of about 150 mm to the slide cam, so that recently in pressing large-sized works for automobile sheet-metal molded parts such as side panels, such coil spring has not satisfied the needs of a long stroke for the slide cam.
Still further, in prior art press devices, particularly large-sized press devices, the face pressure on the slide face becomes as large as about 150 kg/cm.sup.2, so that the wear has been severe; and thus wear prevention is insufficiently provided.
The slide cam has not been properly guided during movement on the slide cam base, so that the slide cam has not always moved precisely.
Further, the slide cam has not been properly guided during moving on the actuating cam, so that the slide cam has not always moved precisely.
USPTO Backgrounds
USPTO Backgrounds