Abstract:
A press die includes a lower die, a slide cam movable along the lower die, and an energizing body disposed between the slide cam and the lower die to abut against both surfaces thereof for biasing the slide cam for movement in one direction along the lower die. The slide cam is provided with a plug having an outer diameter that is larger than an outer diameter of the energizing body and abutting against an end surface of the energizing body. This arrangement enables easy attachment and detachment of the energizing body to and from the press die.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an energizing device for a press die, and more particularly, to an energizing device for a press die that can be easily attached and detached and that is provided to be sufficiently safe. 
     2. Description of the Background Art 
     A conventional energizing device for a press die is shown in FIG.  7  and FIG.  8 . In such a press die, a workpiece, W is mounted on a supporting portion  102  of a lower die  101  such that a hole  105  may be formed in a piercing manner on a lateral surface of the workpiece W by means of a punch  104  that is horizontally arranged with respect to a passive cam  103  performing sliding movements in a lateral direction, wherein the passive cam  103  is driven by an active cam  107  of an upper die  106 . 
     In FIG. 7, the mold assumes a condition at a dead bottom center, and upon completion of the hole forming process, the upper die  106  is raised, and in the absence of pressuring force applied by the active cam  107 , the passive cam  103  is retracted through an energizing force of a coil spring  108  that is provided at a lower portion of the cam until it abuts against a terminating surface  110  of a wall body  109 . 
     Here, the coil spring  108  which functions to retract the passive cam  103  is arranged in that it is outwardly fitted to a guide pin  112  that is formed to be extruded in a horizontal condition by being screwed to a rising wall  111  such that one end surface abuts against the rising wall  111 , and the other end surface is made to abut against a supporting plate  113  wherein this supporting plate  113  is fixed to the passive cam  103  by means of a bolt  114 . 
     The supporting plate  113  includes a groove  115  that is open in a downward direction such that the guide pin  112  may be taken out at the time of performing maintenance or inspection. Due to the groove  115  in the supporting plate  113 , one part of the coil spring  108  abuts against the supporting plate  113 , while a remaining part of the coil spring  108  extends over the groove  115  and is not supported by the supporting plate  113  such that fit of the coil spring  108  with respect to the supporting plate  113  becomes unstable. Consequently, the coil spring  108  can no longer be disposed in a horizontal condition, which results in cases in which the coil spring  108  abuts against an outer periphery of the guide pin  112 , such that the guide pin  112  is worn or the coil spring  108  is deformed or seized so that the energizing device may not be completely actuated. 
     It is desirable to have an energizing device for a press die which is capable of eliminating the above-mentioned drawbacks such as the occurrence of deformation or seizing of the coil spring or damage to the guide pin, and which presents favorable operatability by enabling the coil spring or the guide pin to be easily attached or detached at the time of performing maintenance or inspection without the necessity of detaching the press die from the press machine while such operations can be performed in a safe manner. 
     In view of these facts, the energizing device for a press die according to the present invention has been devised with an energizing body for energizing a press member, by being disposed between two members to abut against both surfaces thereof so as to enable easy attaching/detaching of the energizing body while maintaining a condition in which the energizing body is attached to a press machine, wherein one of the members is provided with a plug of an outer diameter that is larger than an outer diameter of the energizing body and abutting against an end surface of the energizing body. 
     The energizing device for a press die of the present invention is particularly arranged in that the plug is threaded into the one member in order to be attached to the one member. A hexagonal taking-out hole is formed in a concave manner on a surface of the plug opposite to a surface of the plug which abuts with the energizing body. 
     Moreover, the press die includes a taking-out hole of an inner diameter that is larger than the outer diameter of the plug and which is pierced through a wall body of a lower die that is disposed so as to oppose the plug. Further, the press die may include a safety device for preventing jumping-out of the plug and/or the energizing body. The safety device is a safety plate that may be provided in a freely attachable/detachable manner to the one member so as to oppose the plug, or may be provided in a freely attachable/detachable manner on the wall body so as to oppose the plug. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
     FIG. 1 is a longitudinal sectional view showing a condition at a bottom dead center according to one embodiment of the energizing device for a press die according to the present invention; 
     FIG. 2 is a longitudinal sectional view showing a condition of FIG. 1 at a top dead center; 
     FIG. 3 is a longitudinal sectional view showing a condition at a bottom dead center according to another embodiment of the energizing device for a press die according to the present invention employing urethane rubber as an energizing body; 
     FIG. 4 is a longitudinal sectional view showing a condition at a bottom dead center according to still another embodiment of the energizing device for a press die according to the present invention employing a gas spring as an energizing body; 
     FIG. 5 is a longitudinal sectional view showing the energizing device for a press die that is provided with a freely attachable/detachable safety plate at a slide cam opposing a plug; 
     FIG. 6 is a longitudinal sectional view showing the energizing device for a press die that is provided with a freely attachable/detachable safety plate at a portion of a wall body blocking a taking-out hole; 
     FIG. 7 is a longitudinal sectional view showing a conventional energizing device for a press die at a bottom dead center; and 
     FIG. 8 is a view showing main parts of the energizing device of FIG. 7 seen from a direction of arrow VIII. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention as shown in the accompanying drawings will now be explained in details herein below. FIG. 1 shows a press die at a bottom dead center wherein a workpiece W is, for instance, formed with a negative angle. In the drawing, a lower die  1  is comprised with a supporting portion  2  for the workpiece W on the leftward upper side when seen in the drawing, and a columnar body  4  is provided below the supporting portion in a freely rotating manner which includes an intruding forming portion  5  located above a center C of the columnar body  4 . A slide cam  6  is provided at a horizontally arranged guide pin  7  in a freely sliding manner, and negative angle forming is performed through an intruding forming portion  8  that is formed at a leftward upper side of the slide cam  6  and the intruding forming portion  5  of the columnar body  4 . An upper die  9  is provided with an active cam  10  that descends to drive the sliding cam  6 . It should be noted that reference number  11  denotes a pad. 
     Upon completion of negative angle forming, the upper die  9  is raised as shown in FIG.  2 . For retracting the slide cam  6  upon rising of the upper die  9 , a coil spring  12  is provided at a lower portion of the slide cam  6 . 
     The guide pin  7  is horizontally arranged between a rising wall  13  of the lower die  1  and a wall body  14 , and the slide cam  6  performs sliding movements through this guide pin  7 . In case a driving force applied to the slide cam  6  is released upon rising of the active cam  10 , the slide cam  6  is energized by the energizing force of the coil spring  12  that is provided at the lower portion of the slide cam  6  until the slide cam  6  reaches a terminating surface  15  of the wall body  14 . 
     The coil spring  12  is attached to an attaching hole  16  that is horizontally pierced through a lower portion of the slide cam  6  such that one end surface of the spring abuts against a wall surface of the rising wall  13  and the other end surface is attached by being abutted against a plug  17  which has an outer diameter that is larger than an outer diameter of the coil spring  12 . An end surface on an opposite side of the plug  17  at which the coil spring  12  abuts is formed with a concave hexagonal hole  18  for taking-out, and a taking-out aperture  19  is formed through the wall body  14  opposing the hexagonal hole  18  of the plug  17 , and having a dimension that is larger than the outer diameter of the plug  17 . 
     For taking out the coil spring  12  or the plug  17 , a tip of a rotating rod (not shown) having a hexagonal shape is inserted from the taking-out aperture  19  of the wall body  14  into a hexagonal hole  18  of the plug  17  and is rotated for detaching the plug  17  whereupon the coil spring  12  can be taken out. At the time of attaching the coil spring  12 , the rod is again inserted from the taking-out aperture  19  of the wall body  14  into an attaching hole  16  of the slide cam  6  whereupon the plug  17  is inserted from the taking-out aperture  19  of the wall body  14  and screwed thereat to abut against the end surface of the coil spring  12 . 
     While the above explanation is based on an example in which the energizing body of the energizing device for a press die is a coil spring, the energizing body is not limited to a coil spring but may also be made of urethane rubber or cushion rubber, and it may further be a gas spring or any other energizing body. 
     FIG. 3 shows an example in which the energizing body is urethane rubber  31 , and FIG. 4 shows an example in which the energizing body is a gas spring  32 . The gas spring  32  accumulates high-pressure gas in a cylinder  33  thereof, e.g. high-pressure gas of 150 km/cm 2 , depending to various purposes, and even though a rod  34  extruding from the cylinder  33  is expanded or retracted, a substantially constant output of, e.g. 150 km/cm 2 , can be obtained during the entire length of the expanding and retracting process of the rod. The substantially constant output can be achieved during the entire process of the rod  34  through two tanks that are incorporated within the cylinder  33  wherein in case the rod  34  is retracted and pressure is applied to one tank, high-pressure gas is made to flow out from this tank to flow into the other tank. 
     In this manner, the gas spring  32  is capable of performing high output from the start of actuation and during the entire process unlike a case with the coil spring  12  whereby the slide cam  6  can be reliably returned to ensure safety. 
     Further, by the use of the gas spring  32 , the slide cam  6  is enabled to move a distance as long as 150 mm, and processing of a large-sized workpiece of thin plate is also enabled. 
     Due to the provision of the taking-out aperture  19  at the wall body  14  at a portion opposing the plug  17  and the energizing body, it may happen that the plug  17  or the energizing body, or the plug  17  and the energizing body, may jump out through the taking-out aperture  19  and to hit against an operator in case the plug  17  comes off owing to oscillation during usage owing to the fact that the energizing body is highly pressurized. In order to prevent this from happening to improve operatability and to secure safety, a safety plate  34  may be attached at a position opposing the plug  17  of the slide cam  6  as shown in FIG. 5 or a safety plate  35  at the wall body  14  as shown in FIG.  6 . 
     As explained so far, the energizing device for a press die according to the present invention has been devised to be an energizing device for a press die that is comprised with an energizing body for energizing a press member by being disposed between two members to abut against both surfaces thereof, wherein one of the members is provided with a plug of an outer diameter that is larger than an outer diameter of the energizing body and abutting against an end surface of the energizing body. With this arrangement, easy attaching/detaching of the energizing body for energizing a press member can be performed while maintaining a condition in which the energizing body is attached to a press die so that operatability is improved. 
     The energizing device for a press die of the present invention is particularly arranged in that the plug is threaded into the one member in order to be attached to the one member. A hexagonal taking-out hole is formed in a concave manner on a surface of the plug opposite to a surface of the plug which abuts with the energizing body. 
     Moreover, the press die includes a taking-out hole of an inner diameter that is larger than the outer diameter of the plug and which is pierced through a wall body of the lower die that is disposed so as to oppose the plug. Further, the press die may include a safety device for preventing jumping-out of the plug and/or the energizing body. With this arrangement, easy attaching/detaching of the energizing body for energizing a press member can be performed while maintaining a condition in which it is attached to a press die so that operatability is improved. 
     The safety device is safety plate that may be provided in a freely attachable/detachable manner to the slide cam so as to oppose the plug, or may be provided in a freely attachable/detachable manner on the wall body so as to oppose the plug. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.