Abstract:
A punch press, adapted to receive a punch tool having a passage for discharging a fluid for ejecting slugs punched out during the punching process, includes a movable ram means for striking the punch, the ram means having a bottom dead position and including a passage connectable to the passage of the punch when the ram means strikes the punch. The press further includes a valve for controlling the supply of the slug-ejecting fluid to the ram means, the valve comprising a movable member responsive to the vertical motion of the ram means and a stationary member relative to which the movable member slides, the valve being adapted to control the flow of the fluid to the ram means, the valve being open while the ram means is positioned within a predetermined positional range including but not limited to, the dead bottom position of the ram means.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a punch press provided with a function for forcing out a slug punched out during a punching process. 
     2. Description of the Prior Art 
     A conventional punch press that prevents a punched out slug from popping up from the die holder during punch processing by connecting passages in the ram and the punch to form a single passage for flowing high-pressured air in order to force out the slug has been proposed. When the ram nears its dead bottom position, the passage inside the ram connects with the passage formed inside the ram guide, and compressed air is discharged from the bottom of the punch. The force of this air ejection prevents the slug from popping up as the punch is relifted, and causes the slug to drop out. 
     However, sometimes air ejection at the predetermined dead bottom position is insufficient to prevent the slug from popping up. Moreover, if the height of all the punches in the punch press are not constant, even if the ram is arranged such that air discharge occurs when the ram reaches its dead bottom position, optimal timing of the air discharge (optimal timing in order to prevent the slug from popping up, or in other words, discharge timed to the punching action) differs with each different punch. Further, even if punches of a uniform height are used, when some punches are shortened due to abrasion and repeated use, the height at which the end of the punch and the surface of the die meet and the set punching height may differ, causing the air ejection to occur before the punch hits the work, and causing the force of the air discharge to be insufficient to effectively prevent the slug from popping up. The slug can be prevented from popping up by flowing a constant stream of air through the punch, but this wastes most of the air and is not very economical. 
     In order to solve this problem, a means to detect the strike position of the ram, and to open and close a valve in response to the signal detected has been proposed. However, since accurate timing is necessary to supply air to the punch when the ram strikes the punch, a quick-response valve must be provided, increasing the cost of the punch press. 
     BRIEF DESCRIPTION OF THE INVENTION 
     It is a first object of the present invention to propose a simple punch press which reliably forces out a punched out slug, is energy-efficient, and has a simply designed fluid control mechanism. 
     Another object of the present invention to provide a punch press which conducts the fluid supply through the machine using simple parts, and which does not mar the surface of the work with the ejection of the fluid. 
     An additional object of the present invention is to simplify the timing of the discharge of the fluid. 
     An additional object of the present invention is to enable a punch press in which a moveable striker provided in the ram means can selectively strike a plurality of punch tools and reliably force the slug to drop out. 
     An additional object of the present invention is to achieve a simple design in which the air discharge is accurately timed to the ascension and descention of the ram means. 
     In accordance with one, specific, exemplary form of the invention, there is provided a punch press having a ram means containing a passage that aligns with a passage in a punch tool when the punch tool is struck by the ram means. A valve controls a supply of fluid to the ram means, the passage in the punch tool permitting fluid to be discharged from the punch tool passage to eject the slug. The valve is comprised of two sections, a movable section which slides in correlation with the rise and fall of the ram means, and a stationary section which does not move. This valve is arranged such that the valve is maintained in an open state within a fixed vertical range of the rise and fall of the ram means which includes the ram means&#39; dead bottom position. 
     In a punch press according to the invention, the valve is opened in response to the sliding of the movable valve section relative to the fixed valve section each time the ram means strikes the punch tool, ejecting fluid from the punch tool passage. The slug struck by the punch tool is forced out by the discharge of fluid, and is thus prevented from popping up when the punch tool is lifted. Moreover, the valve maintains an open conduit over a fixed range of the rise and fall of the ram means including the point where the ram means reaches its dead bottom position. In other words, fluid discharge is not limited to a single instant in which the ram reaches its dead bottom position, but occurs even after the ram has reached its dead bottom position, continuing until the ram means passes beyond the predetermined vertical range. Thus, the fluid discharge reliably prevents the slug from popping up. Further, the punch press of the present invention achieves greater energy efficiency than a punch press in which fluid discharge occurs continuously since fluid discharge in the present invention occurs after the punch has punched out the slug, and then only when the ram means is located within the fixed vertical range which allows the valve to open. Finally, since the opening and closing of the valve occurs with the movement of the ram means, a separate driving source is unnecessary, and the design of the machine can be simplified. 
     In a punch press comprised as described above, the fluid should preferably be compressed air. If the ejected fluid is compressed air, the facility for supplying the fluid can be simplified, and even if the fluid is discharged to the surface of the work before the punch makes contact with the work, the surface of the work will not be sullied by the fluid. 
     Further, according to a punch press of the present invention, the valve may be composed of a sliding section comprised of a plate-shaped movable member bodily attached to the ram means provided with a passage, and a block-shaped stationary member against which the movable member slides vertically. The term “bodily attached” is herein defined as “attached so as to move as a single body.” The stationary member is provided with a fluid inlet hole and a fluid outlet hole that are normally obstructed by the plate-like surface of the movable section. These inlet and outlet holes align to connect with a through-hole formed in the movable member in accordance with the rise and fall of the movable member. The ram means and the movable member are “bodily attached,” but as per the definition listed above, may actually be formed as separate elements that are fixed to each other enabling them to move as a single unit. 
     With such a design, the fluid inlet hole and the fluid outlet hole of the stationary member are normally obstructed by the plate-like surface of the movable member, or simply put, the valve is normally closed. When the plate-like movable member rises and falls with the movement of the ram means, the fluid inlet and outlet holes in the stationary member come into alignment with the through-hole in the movable member, opening the valve. Hence, the valve design is such that the plate-shaped movable member and the block-shaped stationary member are simply constructed cost-effective elements. 
     The ram means of such a punch press may be comprised of the ram body, and a striker portion which is attached to the bottom of the ram body and may be slidable laterally relative to the ram body. The passage inside the ram means may be provided in the striker portion. In a punch press so comprised, even if the position in which the ram body rises and falls is fixed, by changing the position of the striker, a plurality of punch tools can be selected for striking. Thus, the punch holding means can be equipped with multiple punch tools, and since the passage inside the ram means is provided inside the striker, air can be supplied to the selected punch tool regardless of which punch tool the striker is positioned over. 
     The valve of such a punch press may be positioned adjacent one side of the ram means, and the fluid outlet hole of the valve and the fluid inlet hole of the ram means may be connected by a fluid pipe. In such case, since the valve is provided adjacent one side of the ram means, the valve does not directly bear the load of the punch tool when it is operated, thereby avoiding damaging the valve. 
     Further, since the valve is arranged at a distance from the ram means and the fluid ejection passage of the valve and the fluid inlet passage of the ram means are connected by a pipe, it is possible to design the ram means and the valve as separate units. Thus, the valve can be designed with a simple structure and a degree of freedom. Consequentially, the accurate timing of the air discharge corresponding to the vertical position of the ram means can be designed simply. 
     Further objects, advantages and features of the invention will become apparent from the detailed description, below, when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of a punch press according to a first embodiment of the present invention. 
     FIG. 2 is a top plan view of a portion of the turret of the punch press of FIG.  1 . 
     FIG. 3 is an enlarged, side elevation view, partly in cross section, of the turret and the portion surrounding the turret of the punch press of FIG.  1 . 
     FIG. 4 is an enlarged, side elevation view, partly in cross-section of part of the punch and die set and the punch driving mechanism of the punch press of FIG.  1 . 
     FIG. 5 is an enlarged, side elevation view, partly in cross-section, of a portion of the apparatus of FIG. 4 showing details of a valve in accordance with one aspect of the present invention. 
     FIG. 6A is a front elevation view, partly in cross-section, of the valve of FIG. 4, and 
     FIG. 6B is a top plan view, in cross-section, of the valve of FIG.  4 . 
     FIGS. 7A-C are a side elevation views showing the operation of the valve of FIG.  4 . 
     FIGS. 8 A-I are diagrams illustrating the operation of the valve of FIGS. 5-7 and the corresponding operation of the ram means of the punch press. 
     FIG. 9 is a side elevation view, partly in cross-section, of a punch press in accordance with another aspect of the present invention directed to a malfunction detection means. 
     FIGS. 10A and 10D are side elevation views, in cross-section, showing details of the malfunction detection means of FIG. 9; FIG. 10B is a bottom plan view of the malfunction detection means; FIG. 10C is a cross-sectional view taken along the line XC—XC in FIG.  10 B. 
     FIG. 11 is side elevation view, partly in cross-section, a valve according to another embodiment of the present invention. 
     FIGS. 12A and B are side elevation views, in cross-section, of the valve of FIG. 11 showing the valve during operation. 
     FIG. 13A is an enlarged cross-section diagram showing the openings and surrounding area of the valve of FIG. 11; 
     FIG. 13B is an enlarged diagram showing the openings of the rod-shaped stationary member of the valve of FIG.  11 . 
     FIGS. 14A-I illustrate the operation of the valve of FIG.  11  and the corresponding the operation of the ram means. 
     FIG. 15 is a side elevation view, partly in cross-section, a valve according to a yet another embodiment of the present invention. 
     FIGS. 16A and B are side elevation views, in cross section, of the valve of FIG. 15 illustrating the operation of the valve. 
     FIGS. 17A and B are enlarged cross-section diagrams showing the shapes of the fluid hole openings of the valve of FIG.  15 . 
     FIGS. 18A and B are enlarged cross-section diagrams showing alternative shapes of the fluid hole openings of the valve of FIG.  15 . 
     FIGS. 19A-F are front elevation views showing still further alternative shapes of the fluid hole openings of the valve of FIG.  15 . 
     FIG. 20 is a side elevation view, in cross-section, of a portion of a punch press according to an alternative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A first preferred embodiment of the present invention is now explained in reference to FIG.  1  through FIG.  10 . The punch press of this embodiment is provided with upper and lower turrets  2  and  3  which form the punch holding means, a punch driving mechanism  4 , and a work transporting mechanism  5  attached to a frame  1 . The frame  1  forms a C shape when viewed from the side, with the upper and lower turrets  2  and  3  provided at the concave portion of the C-shaped frame  1 , and the said upper and lower turrets  2  and  3  each supported so as to rotate around the same central axis. 
     The upper turret  2  is provided with multiple rows of punch holders  6  for a punch  7  (FIG. 2) lined up on the circumference around the center of the disk. These punch holders  6  are formed as through-holes, and are arranged in the same concentric plane around the center axis O of the upper turret  2 . An inner row punch holder  6  and an outer row punch holder  6  form a punch holder set arranged on the same radii from the origin around the turret  2 . Each punch  7  is arranged so as to rise and fall into its corresponding punch holder  6 . 
     The lower turret  3  is provided with holders  6 A (FIG. 3) for dies  8  which are lined up on the circumference along the same radii from the center of the disk. The die holders  6 A of the dies  8  are arranged so as to face upwards to meet each punch  7  of the upper turret  2 . The upper and lower turrets  2  and  3  are provided with center sprockets  9  and  10 , respectively, and by means of common motor  11  attached to the frame  1 , are synchronously rotated by a drive imparting mechanism like a chain (not shown in the drawings). An index means  13  which positions the desired punch  7  and die  8  combination at the center of a ram  12  is comprised of the motor  11  and the drive imparting mechanism. The ram  12  is a striking means for the punch  7 . Further, the outer radial surface of the upper and lower turrets  2  and  3  are furnished with position determining holes  14   a  that are positioned opposedly to their corresponding punch holders  6 . These position determining holes  14   a  engage with an index pin  14   b  to hold the turrets  2 ,  3  in position while a pair of index position holding mechanisms  14  that precisely determine the index angle at which the turrets  2 ,  3  are held are provided at the back end of the frame  1 . The index position holding mechanism  14  is comprised from a cylinder device that moves the index pins  14   b.    
     The punch driving mechanism  4  is provided with the ram  12  that strikes the punch  7 , and a punch driving source  15  that drops and lifts the ram  12 . The punch driving mechanism  4  can be either mechanical or hydraulic. In this example, it is hydraulic, with the punch driving source using an oil pressure cylinder. A strike position selection mechanism  16  which selectively drives the punch  7  of the inner or outer row of punch tools on the turret  2  is provided at the ram  12 . The strike position selection mechanism  16  is arranged as described below. 
     The work transporting mechanism  5  is a means for transporting the work sheet laid out on a table  17  to the specified ram position P. The work transporting mechanism  5  is provided with a carriage  18  which moves backwards and forwards (along the Y axis) and attached a cross slider  19  which can move left and right (along the X axis). Multiple work holders  20  which grip the ends of the work W are attached to the cross slider  19 . 
     Free bearings (not shown in the drawings) which support work W are provided in the table  17 . Further, as described in FIG. 3, a turret portion table  21  is provided on the upper surface of the lower turret  3 , in which the said turret portion table  21 , the free bearings  22  are provided. A die portion table  24  is provided at a die holder  23 , in which free bearings  22  are also provided. The die holder  23  is provided at every position of the inner and outer rows of the lower turret  3  supporting the die  8 . The lower turret  3  is provided with a slug drop hole  25  at each position of the die  8 , and a punch load receiving portion  26  at the ram position P of the lower turret  3  is similarly provided with a slug drop hole  27 . 
     As shown in FIG. 4, each punch  7  is provided with a tubular guide member  28  which is combined with the stripper and shearing blade body  29  which is engaged inside a tubular guide member  28  so that it may rise and fall independently. A first restoring spring  30  holds the shearing blade body  29  in a rising state against the guide member  28 . The top end of the shearing blade body  29  thrusts upward against the guide member  28 , and the first restoring spring  30  is provided positioned between a flange spring receiving part  29   a  provided at the top end of the shearing blade body  29  and a flange part  28   a  provided at the top end of the guide member  28 . The punch  7  is supported so as to rise and fall in the turret  2  such that it fits into and rises and falls in the punch holder  6 . Further, the punch  7  is held with constant rising tension in the turret  2  by a second restoring spring  31 , an elastic body positioned between the flange part  28   a  and the surface of the turret  2 . 
     Since the second restoring spring  31  is of a slightly smaller spring constant than the first restoring spring  30 , when the top surface of the punch  7  is pushed by the ram  12 , first the second restoring spring  31  is depressed and the entire punch  7  drops down, and pressure is exerted on work W from the lower surface of the guide member  28 . Next, the first restoring spring  30  is depressed and the shearing blade body  29  drops down against the guide member  28 , opening a punch hole in work W. When the ram  12  rises after reaching its dead bottom position, the shearing blade body  29  is lifted in reverse with the restoring force of the first restoring spring  30 , and after the shearing blade body  29  has pulled out of the punch hole in work W, the entire punch  7  is lifted with the restoring force of the second restoring spring  31 . Because of this action, the guide member  28  accomplishes the stripping function by means of the first restoring spring  30  when the shearing blade body  29  pulls out of the punch hole. 
     The supply of lubricating oil (oil mist) to parts such as the punch  7  must be applied manually by the operator at some place remote from the punching location. However, if it is done automatically, it is necessary to make sure all parts are lubricated. 
     As shown in FIG. 4, the ram  12  of the punch driving mechanism  4  is comprised of the ram body  12   a  and a striker  39  of a strike position selection means  16  provided at the bottom of the ram  12 . The ram body  12   a  is held so as to rise and fall freely inside a ram guide  40  provided in the frame  1 , and is connected to a piston rod  15   a  of the punch driving source  15  comprised of a hydraulic cylinder. A ram means  70  is comprised of the ram  12  and the ram guide  40 . 
     The strike position selecting means  16  is arranged so as to move the striker  39  laterally in a striker guide  41  provided at the bottom end of the ram body  12   a . The striker  39  is comprised of a guide receiver  39   a  which is guided by the striker guide  41 , and the striker body  39   b  which strikes the upper surface of the punch  7  which is fixed below the guide receiver  39   a . The strike position selection means  16  moves the striker  39  by means of a selecting cylinder  42  which comprises the striker moving means. The direction of the lateral movement of the striker  39  in the present embodiment is in the radial direction of the turret. The cylinder body of the selecting cylinder  42  is attached to the striker guide  41  by means of a supporting mechanism  43 . 
     An air supply means  44  is comprised of a passage  45  formed in the striker  39  of the ram  12 , a fluid supply passage  47  which is connected between an entrance of the passage  45  and a fluid supply source  46 , and a valve  48  connected to the fluid supply passage  47 . An outlet hole of the passage  45  formed in the striker  39  connects to a passage  32  of the punch  7 . A flexible fluid pipe  47   a  connects a fluid outlet hole  108  (FIG. 6) on the valve  48  with the passage  45  in the striker  39 . Further, a fluid inlet hole  107  on the valve  48  and the fluid supply source  46  are connected by a flexible fluid pipe  47   b.    
     As shown in FIG. 5, the valve  48  is provided at a sliding part  103  which is formed by a plate-shaped movable member  101  and a block-shaped stationary member  102  which sandwiches the movable member  101 , and rises and falls the movable member  101 . The movable member  101  is provided with a through-hole  106 , and is attached bodily to the ram means  70  by means of a connecting member  104  which bridges the upper section of the movable member  101  with the ram  12 . The connecting member  104  and the movable member  101  are bolted together through a shim  109 . The stationary member  102  is attached to the ram guide  40  through a fastening member  105 . 
     As shown in FIG. 6, the stationary member  102  is provided with the fluid inlet hole  107  and the fluid outlet hole  108  which are aligned through the through-hole  106  according to the rise and fall of the movable member  101 . The fluid inlet hole  107  and the fluid outlet hole  108  are normally obstructed by the plate-like surface of the movable member  101 , and can be connected through the through-hole  106  according to the rise and fall of the movable member  101  which rises and falls with the movement of the ram means  70 . This valve  48  can be set to maintain an open conduit over a fixed or predetermined vertical range of the rise and fall of the ram means  70  which range includes, but is not limited to, the dead bottom position of the ram means  70 . 
     The stationary member  102  is comprised of a stationary member body  110  which is formed in a U shape with parallel opposing valve body portions or sides (FIG.  6 B), and a pair of contact members  111 ,  111  which are provided inside each of the sides of the stationary member body  110 . These contact members  111  in each side of the stationary member body  110  are held so as not to slip out, but allowed to move toward the movable member  101  through pin-shaped guides  112 . One of the contact members  111  is pushed in the direction of the movable member  101  by a spring  116 . This pressure is exerted towards the plate-shaped movable member  101  from the opposing surfaces of the contact members  111 ,  111  causing the movable member  101  to be flexibly gripped. 
     Opposing passages  113 ,  114  as through-holes are formed in each respective side of the stationary member body  110  of the stationary member  102 , and in each respective contact member  111 . Inside each of these passages  113 ,  114 , a sleeve  115  is inserted, and the outer ends of each sleeve  115  are attached through nuts to the fluid inlet hole  107  and the fluid outlet hole  108 , respectively. The sleeves  115  are arranged such that they cut off and do not reach the through-hole  106  side openings  113   a ,  114   a  of each passage  113 ,  114 . Each opening  113   a ,  114   a  is formed directly in the contact member  111  as well. The openings of the through-hole  106  of the movable member  101  and the openings  113   a ,  114   a  of the stationary member  102  are circular in this embodiment, but other shapes can be used. 
     As shown in FIG. 9, the punch press of the present invention is equipped with a malfunction detection means  80  which detects irregular conditions in the machine like strip failures. The malfinction detection means  80  is comprised as described below. 
     The striker body  39   b  in the ram  12  is provided with an operating member  82  which normally exerts pressure downwards by means of a spring  81 , as shown in FIG.  10 . The operating member  82 , which rises when the striker body  39   b  meets the top of the punch  7 , is comprised of a board-shaped operating body  82   a  and an elevating guide part  82   b  which rises from the middle of the top of the operating member  82 . The top of this elevating guide part  82   b  forms a valve  82   c . The position of the operating member  82  in the striker body  39   b  is set at a fixed distance from the center of the part of the punch  7  that is struck, as shown in FIG.  10 B and FIG.  10 C. The operating body  82   a  is arranged so that it can sink into and emerge out of an operating body, encasement groove  84  which is situated at the aforementioned predetermined distance from the punch. The passage  45  which is used to force out the slug is provided in the center of the striker body  39   b , and does not connect with the operating member  82 . 
     A guide hole  86  which guides the rise and fall of the elevating guide part  82   b  in the operating member  82  is formed such that it partially ascends the inside surface of the operating body encasement groove  84 . The guide hole  86  is a fluid passage used as the detector. A fluid passage  87  of slightly smaller diameter than the guide hole  86  is formed above the guide hole  86  in a vertical direction entering into the guide receiver  39   a  of the striker  39 . A spring  81  which exerts downward force on the operating member  82  is arranged in the guide hole  86 , and is engaged between the top of the elevating guide part  82   b  of the operating member  82  and the top of the guide hole  86 . The spring constant of the spring  81  is set to a relatively smaller value than that of the first or second restoring springs  30  and  31  of the punch  7 . Further, a brace  82   d  is formed so that it juts out from both ends of the top of the operating body  82   a , and a ring-shaped stopper  88  is arranged in the bottom of the striker body  39   b  so as to block the brace  82   d . Thus, the thrusting force brought against the operating member  82  from the bottom of the striker body  39   b  is kept below a fixed level by the stopper  88 . 
     An air exhaust passage  89  extending laterally in the striker  39  and opening into the outer surface of the striker body  39   b  connects to the middle of the passage of the guide hole  86  in the striker body  39   b . The air exhaust passage  89  is positioned such that when the striker body  39   b  meets the top of the punch  7  causing the operating member  82  to rise (FIG.  10 A), the valve  82   c  of the operating member  82  blocks the air exhaust passage  89 , and such that when the striker body  39   b  is not in contact with the top of the punch  7  and the operating member  82  descends (FIG.  10 D), valve  82   c  opens the air exhaust passage  89 . 
     As shown in FIG. 10A, in the striker body  39   b  which comprises the striker  39 , a lateral air supply passage  90  which connects to the air passage  87  in the striker body  39   b  is formed in the direction of the lateral movement of the striker  39 . An air supply pipe  91  which is connected to the striker guide  41  is inserted into the air supply passage  90 . The air supply pipe  91  is provided with the air outlet hole  92 . This air supply pipe  91  ensures that the air supply reaches the air supply passage  87  in the striker body  39   b  without having to laterally move the striker  39 . As shown in FIG. 9, the air supply pipe  91  is connected to an air supply source  93 , and an air pressure sensor  94  which functions as a detection means for detecting the state of the operating member  82  is arranged between the air supply source  93  and the air supply pipe  91 . The air pressure sensor  94  is equipped with something like a switch. The air passage  87  inside the striker body  39   b  and which runs into the air pressure sensor  94  switches between connected and obstructed states by means of opening and closing of the air exhaust passage  89  by a valve  82   c  in response to the sinking and rising of the operating member  82 . Thus the air pressure sensor  94  can detect changes in the backwards pressure of the air supplied as far as the operating member  82  which correspond to the sinking and rising of the operating member  82 . The air pressure sensor  94  may also be provided in the air exhaust passage  89 . 
     An NC device is used as the control device  95  for controlling the entire punch press. This control device  95  is equipped with a numerical control function and a programmable controller. The control device  95  is provided with a monitoring means  96  which monitors the rise and fall of the ram  12 , and two determining means  97 ,  98  which determine whether there is a mechanical malfunction. The monitoring means  96  can either monitor the vertical position of the ram  12  via the output of a position detecting means (not shown in the drawings) which directly determines the position of the ram  12 , or via the output of a position detecting means provided in the punch driving source  15 . In the case when a servo motor is used as the punch driving source  15 , a pulse coder attached to the servo motor can be used as the position determining means. 
     The first determining means  97  determines whether there is a malfunction by means of determining the position of the ram  12  detected by the monitoring means  96  or by determining if the detected signal from the air pressure sensor  94  differs from the established parameters. In the present embodiment, the first determining means  97  is a strip failure detecting means which determines that a strip failure has occurred if the air pressure sensor  94  detects that the operating member  82  is not in contact with the punch  7  when the ram  12  has been relifted. 
     The second determining means  98  is a means to detect if the detecting function is malfunctioning. When the ram  12  is located between the position corresponding to the restored height of the punch  7  and the ram  12 &#39;s highest ascension, and the air pressure sensor  94  detects a strip failure, the first determining means  98  is determined to be faulty. 
     The operation of the punch press will now be explained. The desired punch  7  and the die  8  of the upper and lower turrets  2 ,  3 , respectively, are brought into striking position at ram position P by the rotation of the turrets  2 ,  3 . The punch  7  to be used is selected from either the inner or outer row of the turret  2  through the movement of the striker  39  by selecting the cylinder  42  of the ram  12 . The ram  12  is then lowered by the punch driving source  15 , causing the desired punch  7  to be struck by the striker  39 , and punching a punch hole in the work W. 
     When punch processing takes place, the valve  48  is opened at the ram position P. Compressed air is passed through the passage  32  of the punch  7  and ejected from a discharge hole at the tip of the shearing blade body  29 . The ejected air prevents the punched out slug from popping up out of the die  8  and out of the work W, and forces the slug to drop out. 
     When the ram  12  is in its highest ascension, the movable member  101  of the valve  48  is positioned relatively higher than the stationary member  102 , as shown in FIG.  7 A. The fluid inlet hole  107  (FIG. 6A) and the fluid outlet hole  108  are thus obstructed by the movable member  101 , forming a closed conduit. The movable member  101  falls bodily with the ram  12 , and when the ram  12  reaches a predetermined height, the fluid inlet hole  107  and the fluid outlet hole  108  align with the through-hole  106  forming an unobstructed conduit as shown in FIG.  7 B. Thus, compressed air is passed through the valve  48  into the passage  45  in the striker  39 , and then supplied to the passage  32  inside the punch  7 . 
     FIG. 8 shows the relationship between the opened (aligned) state of the valve  48  and the vertical position of the ram  12 . Pairs A and B, B and F, C and G, and D and H in FIG. 8 show various states of the valve during operation. 
     When the raised ram  12  in FIG. 8E is lowered, and reaches a predetermined height slightly above its dead bottom position (as shown in FIG.  8 ), the fluid inlet hole  107  and the fluid outlet hole  108  come into alignment with the through-hole  106 , as shown in FIG.  8 B and FIG.  7 B. The fixed height at which the fluid inlet hole  107  and the fluid outlet hole  108  align with the through-hole  106  and open the conduit is set at the position where the bottom of the punch  7  reaches the position denoted in this example as DH (Die Height). The alignment of these passages permits the start of air supply to the passage  32  inside the punch  7 . This supply of air is maintained after reaching this alignment, after the ram  12  reaches its dead bottom position (the state shown in FIG. 7C, FIG.  8 C and FIG.  8 G), and until the ram  12  returns to the predetermined height DH at which the passage was opened. In other words, air supply is maintained over the entire vertical range denoted by S in FIG.  8 . 
     Hence, discharge of compressed air from the punch  7  is maintained for a short moment after the punch process is completed. Consequentially, the slug Ws is reliably forced out, and the prevention of the slug Ws from popping out becomes more effective. In other words, contrary to conventional machines that only eject a discharge air the instant the ram reaches its dead bottom position and thus create a vacuum at the surface of the work which can pull the slug upwards with the punch  7 , when the punch  7  and the upper surface of the slug Ws come into contact in a punch press of the present invention, air discharge is continued even when the ram is slightly above its dead bottom position, no vacuum is created, and consequentially the slug Ws is forced out with a higher degree of reliability. 
     In order to reliably force out the slug, the vertical range S should preferably be made relatively large. In order to decrease wasted air discharge, the following design is preferable. When the punch  7  is lowered and the bottom of the punch  7  approaches the die height DH, the vertical range S is set such that the fluid inlet hole  107  and the fluid outlet hole  108  begin to align through the through-hole  106 , thus reducing the wasted air discharge before the punch  7  contacts the work W. Further, wasted air discharge is prevented even if the height of the punch  7  is changed. 
     In other words, the shearing blade body  29  of the punch  7  may be shortened due to abrasion or repolishing. Normally changes in the height of the shearing blade body  29  must be dealt with by adjusting the height of the part of the punch  7  which is struck by the ram  12  and which is attached to the top part of the punch  7  with something like a screw. This kind of adjustment can be used to adjust the heights of all the punch  7 . However, this adjustment must be performed by the operator, and there may be times when the operator forgets to make the necessary adjustments, or makes improper adjustments. In such instances, the length L of the punch  7  is shortened (as shown in FIG.  8 I), but the length that is lost will be less than the thickness of the work W. Thus, even if the adjustment of the height of the punch  7  after repolishing is inaccurate, the height at which the connection is opened through the through-hole  106  is set at the die height DH, and the connection is formed at or near the die height DH, and as shown in FIG. 8I, the connection is formed when the punch  7  is punching into the work W. Thus, even if the adjustment of the height of the punch  7  after repolishing is inaccurate, the difference in height is compensated by the thickness of the work W, and wasted air discharge is prevented. Further, the amount of time that the air is discharged can be lengthened, enabling the slug Ws to be more reliably forced out. 
     The punch press of the present invention thus reliably forces out the slug and prevents the wasting of compressed air during air discharge. Further, since the valve  48  which is used to supply the compressed air is opened and closed in accordance with the movement of the ram  12 , a separate driving source is unnecessary, the design is simple, and control of the air supply occurs in response to the rise and fall of the ram  12 . 
     The malfunction detection means  80  functions as described below. When a strip failure is created during punch processing, or in other words, when the punched out work W fails to dislodge from the shearing blade body  29  of the punch  7 , preventing the punch  7  from returning to its set height. When the punch  7  is unable to return to its highest ascension, the striker  39  of the ram  2  separates from the punch  7 . Thus, the operating member  82  is pushed down by the force of spring  81  (as shown in FIG.  10 D), and the air exhaust passage  89  is opened. 
     In other words, as shown in FIG. 10D, the operating member  82  is lowered inside the striker  39  when not thrust against the punch  7 , and the air exhaust passage  89  from the air passage  87  is opened. Further, when the operating member  82  is pressed against the punch  7  by the striker  29 , it rises up, as shown in FIG. 10A, and closes the air discharge passage  89 . Thus, when a strip failure occurs, the striker  39  rises until it reaches the set position to which the punch  7  is relifted, the operating member  82  falls against the striker  39 , and the air discharge passage  89  is opened. The operating member  82  remains lowered and the air discharge passage  89  remains open while the striker  39  returns to the fixed height corresponding to the relifted height of the punch  7 . 
     When the air discharge passage  89  is opened and the air pressure in the air passage  87  decreases, this decrease in air pressure is detected by the air pressure sensor  94 . 
     When the first determining means  97  detects that the air pressure reduction detected by the air pressure sensor  94  occurs faster than normal, in other words, when the ram  12  is relifted, it is detected that a strip failure has occurred. 
     Thus, the malfunction detection means  80  thus organized is able to determine whether or not a strip failure has occurred by detecting the state of the operating member  82  arranged in the striker  39 , and by determining the vertical position of the striker  39 . Moreover, contrary to conventional strip failure detection means that run an electric current between the striker and the punch and can fail to reliably detect strip failures because of insufficient contact between the ram and punch, and because of insulation of the punch head impeeding the current, this malfunction detection means reliably detects the strip failures. Further, the operating member  82  is arranged as an independent part of the striker  39  that strikes the punch  7 , and since it does not bear the load of the striker  39 , the longevity of the malfunction detection means  80  can be improved. 
     Packing may be used to seal the connection between the passage  32  in the punch  7  and the passage  45  in the striker  39  so that when the striker  39  meets the punch  7  the connection between the passages  45  is air-tight. However, in the present embodiment, the operating member  82  is positioned at a distance from the center of the striker body  39   b , and in order not to obstruct the sinking of the operating member  82  into the striker body  39   b , packing is not used. 
     The second determining means  98  determines that there is a malfunction when the air pressure sensor  94  detects that the punch  7  and the striker  39  are in contact when the ram  12  is positioned between its fixed height corresponding to the highest ascension of the punch  7  and the ram  12  dead top position. This malfunction detection may be caused by strip failure or a faulty sensor. 
     When the ram  12  is positioned between the fixed height corresponding to the restored height of the punch  7  and its highest ascension, it is not possible for the punch  7  and the striker  39  to be in contact during normal operation. Consequentially, when the air pressure sensor  94  detects that the punch  7  and the striker  39  are in contact when the ram  12  is in this range, a malfunction is detected. Provided with this kind of the malfunction determining means  98 , an operator can instantly tell if there is damaged caused by a stripping malfunction. Thus, the reliability of the strip miss detecting function is improved. 
     In such a punch press, the forcing out of the slug can be performed reliably, and stripping malfunctions can be reliably detected. 
     In the embodiment described above, the valve  48  may be structured as shown in FIG.  11  through FIG.  14 . The valve  48 B in this example is formed from the rod shaped stationary member  49  and the tubular moving member  50  which is engaged and permitted to slide against the surface of the stationary member  49 . The stationary member  49  is attached at the bottom to the ram guide  40  through the connecting member  51 . The tubular moving member  50  is affixed at the top to the ram  12  through the connecting member  52 . The stationary member  49  and the moving member  50  are provided with the passages  53  and  54 , respectively, which move between connected and obstructed states in response to the rise and fall of the moving member  50 . 
     As enlarged in FIG. 11, the stationary member  49  of the valve  48 B is provided with the vertical passage section  53   a  of the passage  53  which extends vertically through the center of the valve. The vertical passage section  53   a  is formed as a vertically extending hole capped at the top. The bottom of the vertical passage section  53   a  becomes a fluid outlet hole which connects with the fluid pipe  47   a  through a pipe joint. The opening  53   c  of the passage  53  is formed in the sliding section  69  between the stationary member  49  and the movable member  50  in the outer surface somewhere in the mid-height section of the stationary member  49 . This opening  53   c  is formed as a rounded, groove the bottom circumference of which contains at multiple fixed locations a number of lateral passage sections  53   b  which join the vertical passage section  53   a  with the opening  53   c . The opening  53   c  which is formed as a rounded groove is formed so as to widen vertically from the lateral passage section passage  53   b . This passage widens in the sliding direction of the movable member  50  into the opening  53   c  which is slightly larger than the opening  54   c  of the movable member  50 . 
     The movable member  50  is comprised of two elements, a movable member body  71  and a sleeve  72  which is engaged so as to slide inside a hole formed in the movable member body  71 . The sleeve  72  slides against the outside of the stationary member  49 . 
     A cap  74  which is provided with a hole passing through the stationary member  49  is provided at the top of the movable member body  71 , and this cap  74  controls the top position of the sleeve  72 . The cap  74  is bolted to the movable member body  71 . The movable member  50  is connected to the top surface of the cap  74  and affixed with a separate bolt to the connecting member  52 . 
     A sleeve bottom holding member  75  is arranged at a distance below the movable member body  71 . The sleeve bottom holding member  75  receives the bottom of the sleeve  72  which is inserted into a hole in its upper surface. 
     The passage  54  of the movable member  50  is formed of a body passage section  54   a  provided in the movable member body  71  and an opening  54   c  provided in the sleeve  72 . The opening  54   c  in the sleeve  72  is formed in the passage  54  of the sliding section  69  wherein the stationary member  49  and the movable member  50  slide against each other. This opening  54   c  forms a through-hole, and is arranged in multiple positions around the circumference of the sleeve  72 . The passage section  54   a  is comprised of a single hole extending laterally inside the movable section body  71 , and tapered passage section  54   b  provided in the inner surface of the movable section body  71 . The tapered passage section  54   b  is formed as a rounded groove tapered out towards the outer surface in the longitudinal direction of the sleeve  72 , its radius at the outermost end larger than that of the opening  54   c . The opening of the other end of the body passage section  54   a  is the entrance hole, and connects through a joint to the pipe  47   b  formed of a flexible tube and to the fluid supply passage  47 . 
     Seals  77  and  78  are arranged in the outer surface of the stationary member  49  above and below the openings  53   c  which form a circular groove in order to prevent air from leaking out of the sliding member  69 . Further, seals  79  are provided in the inner surface of the movable member body  71  of the movable member  50  and are arranged above and below the tapered passage section  54   b  formed in the tubular groove in order to prevent air from leaking out from between the movable member body  71  and the sleeve  72 . The seals  77  and  78  are composed of O-rings or the like which are inserted around the tubular groove formed in the outer surface of the stationary member  49 . The seal  79  is composed of an O-ring which is inserted around the tubular groove of the inner surface of the movable member body  71 . 
     When the ram  12  is in its rising state, as shown in FIG. 12A, the movable member  50  is relatively higher than the stationary member  49 , both passages  53 ,  54  are obstructed, and the valve  48 B is closed. When the movable member  50  falls bodily with the ram  12  and the ram  12  reaches a predetermined location, as shown in FIG. 12B, the passages  53 ,  54  of the stationary member  49  and the movable member  50  align. This permits compressed air to pass through the valve  48   b , through the flow passage  45  inside the striker  39 , and to be supplied to the passage  32  inside the punch  7 . 
     FIG. 14 shows the relationship between the alignment of the passages  53  and  54  and the rise and fall of the ram  12 . Figures A and E, B and F, C and G, and D and H each show the corresponding states of the alignment according to operation of the ram  12 . 
     From the rising state of the ram  12  shown in FIG. 14E, the ram  12  drops down and when it reaches a fixed point above its dead bottom position (this point shown in FIG.  14 F), the passage openings  53   c  of the stationary member  49  and the openings  54   c  of the movable member  50  of the valve  48   b  begin to come into alignment (as shown in FIG.  14 B). The set height at which this alignment begins in this example is the height at which the bottom of the punch  7  reaches the die height DH. The start of this alignment opens the valve and starts the supply of air to the passage  32  inside the punch  7 . After the passages have come into alignment and the ram  12  continues past its dead bottom position, all of the opening  54   c  of the movable member  50  aligns with the opening  53   c  of the movable member  49 , and the valve becomes completely open. The complete opening of the valve occurs when the ram  12  reaches its dead bottom position (shown in FIG.  14 G), and the complete opening of the valves is maintained until the ram  12  is lifted beyond fixed height HO (shown in FIG. 14H) and passed out of a vertical range S B . 
     The valve depicted in the embodiment above may be changed according to the following alternate embodiment described in reference to FIG.  15  through FIG.  17 . This valve  48 A engages the movable member  50 A which is attached bodily to the ram outside of the stationary section  49 A, and slides against it. The stationary member  49 A and the movable member  50 A are attached to the ram guide  40  and the ram  12 , respectively, via the connecting members  51  and  52 , respectively. 
     The passage  54 A provided with the opening  54 Ac which opens into the sliding section  69  between the movable member  50 A and the stationary member  49 A is provided at mid-height in the movable member  50 A. The opening of the entrance side of the passage  54 A is connected to the air supply source  46  (shown in FIG. 4) via the fluid pipe  47   b  which forms part of the air supply passageway  47 . 
     The stationary member  49 A is provided with the air supply passage  53 A and an oil supply passage  55  which flows lubricating oil inside the valve. The air passage  53 Aa is composed of a vertical passage section  53 Aa which extends from the bottom of the stationary member  49 A and curves into a lateral passage section. The lateral passage section is provided with an opening  53 Ac which opens into the sliding section  69 . The opening at the bottom of the vertical passage section  53 Aa is attached to the fluid pipe  47   a.    
     The opening  53 Ac of the sliding section  69  of the stationary member  49 A is tapered and widens out in the sliding direction of the movable member  50 A to a radius larger than that of the opening  54 Ac of the movable member  50 A. This widening section establishes the vertical range of the ram means  70  in which the dead bottom position is included, and inside which the opening  53 Ac of the stationary member  50 A and the opening  54 Ac of the sliding section  69  of the movable member  50 A align to maintain the valve in a completely open state. 
     Moreover, as shown in this embodiment, when the opening  53 Ac of the stationary member  49 A and the opening  54 Ac of the movable member  50 A are formed in the valve  48 A such that one of the holes widens to a diameter larger than the other in the sliding direction of the movable member  50 A, the following benefits are achieved. Namely, by appropriately setting the size of the larger opening  53 Ac which opens in the sliding direction, the range of the completely opened state of the valve can thus be set. This makes setting the range in which the valve is completely open very simple. 
     As shown in FIG. 15, the inner valve lubricating oil supply passage  55  of the stationary member  49 A extends in a vertical direction from its upper end, and is formed such that lubricating oil outlet holes  55   a  open into the sliding section  69  in a position slightly below the opening section of the air supply passage  53 A and slightly above the air supply passage  53 A of the movable member  50 A when the ram  12  is at its highest ascension. The seals  57  which prevent air from leaking out of the sliding section  69  are provided above and below each lubricating oil outlet hole  55   a . These seals  57  use O-rings that fit around the rounded grooves provided on the surface of the stationary member  49 A. The opening end of the inner valve lubricating oil supply passage  55  is attached through a tube to the lubricating oil supply source (not shown in the drawings). 
     When thus supplied with the inner valve lubricating oil supply passage  55 , sliding of the sliding member  50 A between the stationary member  49 A and the movable member  50 A occurs smoothly. 
     Moreover, as shown in the embodiments of FIG.  11  through FIG. 14, when the movable member  50  of the valve  48  is structured in two parts, the inner valve lubricating oil supply passage  55  can be provided, as shown in the embodiments in FIG.  15  and FIG.  16 . 
     In the above described embodiment, the opening formed so as to taper out in the sliding direction in the sliding section  69  of the valves  48 A and  48 B are provided in the the stationary members  49  and  49 A, but conversely, they can also be formed in the opening  54   c  of the passage  54  of the movable member  50  as shown in FIG.  18 . 
     Further, the openings of the sliding section  69  provided in the passages  53  and  54  can be formed in the sliding direction in both the stationary member  49  and the movable member  50 . Still further, these tapered openings can take on various shapes as shown in the examples in FIG.  19 A through FIG.  19 F. For example, FIG. 19A shows an elliptical opening  53   c , FIG. 19B shows the opening  53   c  made into a groove shape with semi-circular ends, FIG.  19 C and FIG. 19D are each examples of the opening  53   c  made into groove shapes with the top and bottom ends, respectively, ending in semi-circles, FIG. 19E is an example of the tapered opening  53   c  formed in a rectangular shape, FIG. 19F is an example of the tapered opening  53   c  made into a groove-like shape as in FIG. 19B, but of the same width as the passage  53 . 
     FIG. 20 shows an alternate embodiment of the present invention. In this embodiment, the punch  7  of the turret  2  is provided with only a single row of punch tools, and the ram  12 A lacks a strike position selection means for adjusting the strike position or the ram  12 A. Further, a valve  61  provided with the fluid supply passage  47  is comprised of the sliding section  64  between the ram guide  62  and the ram  12 A as a movable member. An entrance opening  63   c  of a passage  63  which is provided in the ram  12 A is provided at the sliding section  64  between the ram  12 A and the ram guide  62 . The outlet side opening of the passage  63  is arranged at the bottom of the ram  12 , and connects with the passage  32  of the punch  7 . The opening  65   c  of the passage  65  which is provided in the ram guide  62  opens at the sliding section  64 , and is formed so as to be wider (in the sliding direction) than the corresponding opening  63   c . The entrance opening of the passage  65  in the ram guide  62  is connected to the pressurized air supply source via a pipe. Otherwise, the organization of this embodiment is the same as the embodiments shown in FIG.  1  through FIG.  10 . 
     The punch press described in this alternate embodiment, like the previously described punch presses, reliably forces out slugs and performs air discharge economically in a simple and effective design. 
     Further, the present embodiment may also be modified by making the tapered opening in either the passage  63  of the ram guide  62  or the passage  65  of the ram  12 A. Further, the shape of the tapered openings can also be altered to extend in different shapes in the sliding direction as described in FIG.  19 . 
     The embodiments described above have been explained in reference to a turret style punch press, but a straight advancing cartridge can be used instead of the turret as the punch holding means to hold the punch  7  and the die  8 . Further, other designs, such as a punch holding means that connects the part which holds the individual punches  7  and the dies  8  by means of a chain, can also be implemented with this invention. 
     Since the punch press of the present invention is equipped with a valve that forces out a slug by maintaining a passage when the ram means falls between a fixed vertical range which includes its dead bottom position, the slug is reliably forced out, and energy used to supply the air is not wasted. Further, since the valve is opened and closed by the movement of the ram means, a separate driving source is not required, and the design of the fluid control means is kept simple. 
     Since compressed air is used as the fluid, it can be supplied through the machine with unsophisticated machinery, and even if discharge of this fluid occurs before the punch strikes the work, the work is not sullied by the fluid. 
     When the valve is comprised of a sliding section, said sliding section comprised of a plate-shaped movable member which is provided with a through-hole and which is attached bodily to the ram means and a block-shaped stationary member that clamps the vertically sliding movable member wherein said valve is provided with a through-hole, a fluid inlet part, and a fluid outlet part which come into alignment in accordance with the rise and fall of the plate shaped movable member, the valve design is a relatively simple one-part construction, and the cost of manufacturing the valve can be minimized. 
     When the ram means is provided with a ram body, and a striker which is attached to and moves the bottom of the ram body in a lateral direction, and provided with a passage in the striker, the striker of the ram means is able to selectively strike a plurality of punches while still reliably forcing out the slugs. 
     When the valve is provided laterally of the ram means and the fluid outlet port of the valve and fluid inlet port of the ram means are linked by a pipe, a design in which fluid discharge accurately corresponds to the rise and fall of the ram means can be achieved.