Title:
PUNCH PRESS WITH IMPROVED SLUG HANDLING SYSTEM
United States Patent 3800643


Abstract:
A punch press includes a bin mounted below a die and communicating with the latter by way of a passage which directs slugs punched from the workpiece into the bin. A vacuum source is connected to a pipe leading from the bin and draws the slugs through the passage and into the bin. Mounted beneath a door in the bottom of the bin is a power operated conveyor for transporting the slugs away from the bin. The door may be opened automatically during an interruption in the punching operation of the press whereby the slugs are dumped onto the conveyor after the latter is actuated to carry the slugs away from the bin. During the punching operation, refrigerated air and lubricant are forced under pressure into a chamber defined by a stripper housing which encloses the punch, the lubricant and the air forming a mist for cooling the punch. As the mist escapes from the chamber through an opening in the stripper, it is drawn into the die by the vacuum and thus also cools and lubricates the die. Excess lubricant is drawn through the bin into the pipe and is separated from the air by a filter at the discharge end of the pipe before the air is exhausted into the atmosphere.



Inventors:
Scott, William B. (Steward, IL)
Sawvell, Roger V. (New Milford, IL)
Application Number:
05/274396
Publication Date:
04/02/1974
Filing Date:
07/24/1972
Assignee:
WHITNEY W CORP,US
Primary Class:
Other Classes:
83/168, 83/169, 83/171, 83/916
International Classes:
B26D5/12; B21D28/00; B21D28/02; B21D28/20; B21D37/18; B21D45/00; B26D7/18; (IPC1-7): B26D7/18
Field of Search:
83/916,100,98,168,169,170,171
View Patent Images:
US Patent References:



Primary Examiner:
Lake, Roy
Assistant Examiner:
Coan, James F.
Attorney, Agent or Firm:
Wolfe, Hubbard, Leydig, Voit & Osann Ltd.
Claims:
We claim as our invention

1. A punch press having a vertically reciprocable punch adapted to coact with an underlying die to punch holes in an intervening workpiece, said press including a bin disposed below said die to collect the slugs punched from the workpiece, a passage communicating between the die and the bin, a vacuum source connected with said bin to draw the slugs through the passage and into the bin, a door mounted on the bin to move to an open position to enable the removal of the slugs from the bin, a conveyor disposed below the door to carry the slugs away from the bin, and means for automatically opening said door to dump the slugs onto the conveyor during an interruption in the punching operation of said press.

2. A punch press having a vertically reciprocable punch adapted to coact with an underlying die to punch holes in an intervening workpiece, said press including a bin disposed below said die to collect the slugs punched from the workpiece, a passage communicating between the die and the bin, a vacuum source having a suction pipe and a discharge pipe, said suction pipe being connected to the bin to draw the slugs through the passage and into the bin, a door mounted on the bin to move to an open position to enable the removal of the slugs from the bin, a conveyor disposed below the door to carry the slugs away from the bin, power means for operating said conveyor, mechanism for opening said door to dump the slugs onto the conveyor, and signal responsive means operable to disable the vacuum source, to actuate the conveyor power means and to actuate said door mechanism to open the door and dump the slugs on the conveyor for transportation away from the bin.

3. A punch press as defined by claim 2 including a limit switch mounted on said bin and operable to detect when said bin door is opened partially and to produce an electrical signal in response thereto.

4. A punch press as defined by claim 3 wherein said door mechanism includes a fluid-actuated cylinder, a rod extending from said cylinder, said rod and said cylinder being connected to said door whereby the latter is closed and opened by advancing and retracting said rod within said cylinder, and said signal responsive means being operable to actuate said cylinder to retract the rod and open the door.

5. A punch press with a vertically reciprocable ram mounted on a frame, a punch carried on the lower end of said ram and adapted to coact with an underlying die to punch holes in an intervening workpiece, said press including a bin mounted on said frame below said die to collect the slugs punched from the workpiece, a passage communicating through the frame between the die and the bin, an exhaust pipe with an inlet end connected to the bin, a vacuum source connected to the pipe to draw the slugs through the passage and into the bin, a door mounted on the bottom of the bin to pivot about a substantially horizontal axis between an open position and a closed position, said door sealingly engaging the bin when in said closed position, a belt-type conveyor disposed below the door to carry the slugs away from the bin, power means for operating said conveyor, mechanism for opening said door to dump the slugs onto the conveyor during an interruption in the punching operation of the press, said mechanism including a fluid-actuated cylinder and rod connected between said door and said frame to close and open said door by advancing and retracting said rod within the cylinder, and means operable during said interruption to disable said vacuum source, to actuate the conveyor power means and to actuate said cylinder to open the door and dump the slugs on the conveyor for transportation away from the bin.

6. A punch press having a vertically reciprocable punch adapted to coact with an underlying die to punch holes in an intervening workpiece, said press including a bin disposed below said die to collect the slugs punched from the workpiece, a passage communicating between the die and the bin, a vacuum source connected with said bin to draw the slugs through the passage and into the bin, a door on the bin for movement to an open position enabling removal of the slugs from the bin, a conveyor disposed below the door to carry the slugs away from the bin, means for automatically opening said door to dump the slugs on the conveyor during an interruption in the punching operation of said press, a housing disposed around the punch and defining an enclosed chamber, and means for forcing refrigerated air and lubricant under pressure into said chamber to form a mist around the punch for lubricating and cooling the latter, said mist also cooling and lubricating the die by being forced by said means out of the chamber through an opening in the bottom of said housing to be drawn across the exposed surfaces of said die by said vacuum.

7. A punch press having a vertically reciprocable ram carrying a punch adapted to coact with an underlying die to punch holes in an intervening workpiece, said press including a bin disposed below said die to collect the slugs punched from the workpiece, a passage communicating between the die and the bin, a vacuum source having a suction pipe and a discharge pipe, said suction pipe being connected to draw the slugs through the passage and into the bin, a sealed door in the bin and adapted to be opened to remove the slugs from the bin, a conveyor disposed below the door to carry the slugs away from the bin, power means for operating said conveyor, mechanism for opening said door to dump the slugs onto the conveyor during an interruption in the punching operation of said press, means operable during said interruption to disable the vacuum source, to actuate the conveyor power means and to actuate said door mechanism to open the door and dump the slugs on the conveyor for transportation away from the bin, a housing defining an enclosed chamber disposed around the punch at the lower end of the ram, means for forcing refrigerated air into said chamber, means for forcing lubricant into said chamber to form a mist of cold air and lubricant around the punch for lubricating and cooling the latter, said mist also cooling and lubricating the die by being forced out of the chamber through an opening in the bottom of the housing to be drawn across the exposed surfaces of said die and into the bin by said vacuum, and a filter connected to said discharge pipe to separate the lubricant from the air before the air is exhausted into the atmosphere.

8. A punch press having a reciprocable ram carrying a punch adapted to coact with an underlying die to punch a hole in an intervening workpiece, said press including a housing defining a substantially enclosed chamber disposed around said punch and having a lower opening for admitting said punch therethrough to punch a hole in said workpiece, and means for forcing refrigerated air and lubricant into said chamber under pressure to form a mist of the lubricant around the punch for lubricating and cooling the latter, said means also forcing the mist out of said lower opening to cool said underlying die.

9. A punch press with a vertically reciprocable ram mounted on a frame, a punch carried on the lower end of said ram and adapted to coact with an underlying die to punch a hole in an intervening workpiece, said press including a housing mounted on said frame around the lower end of said ram and defining a substantially enclosed chamber around said punch, said housing having a bottom plate with a central opening therein to admit said punch therethrough to punch a hole in said workpiece, and means for forcing refrigerated air and lubricant into said chamber under pressure to form a mist of the lubricant around the punch for lubricating and cooling the punch and for forcing the mist out of said housing through said opening and toward said die, an exhaust pipe with an inlet end communicating with said die, a vacuum source connected with said pipe to draw the lubricant into the die to lubricate and cool the exposed surfaces of the die and to exhaust the excess lubricant through the pipe.

10. A punch press as defined by claim 9 including means for purging said chamber of said mist prior to changing punches on the end of the ram to avoid releasing the mist into the atmosphere around the punch press.

11. A punch press as defined by claim 10 in which said purging means include an air hose communicating with the top of said chamber through said housing and a pressure source for forcing clean air through said hose to purge the chamber of lubricant by driving the mist out of the chamber through the opening.

12. A punch press as defined by claim 11 wherein said means for forcing refrigerated air and lubricant into the chamber includes two nozzles located adjacent the sidewalls of said housing at angularly spaced positions from each other to direct the lubricant in generally opposing directions past opposite sides of the central axis of the ram to create a swirling of the mist in the chamber.

13. A punch press as defined by claim 10 including a filter connected to the outlet of said pipe to separate the lubricant from the air before the air is exhausted into the atmosphere.

Description:
BACKGROUND OF THE INVENTION

This invention relates generally to a punch press and, more particularly, to the type of press which includes a system for keeping the punch and the die from overheating during a punching cycle and for collecting the slugs punched out of the workpiece. Prior systems used for these purposes include a passageway which establishes communication between the die and a collection bin, there being a vacuum source associated with the bin to draw the press through the passageway and into the bin. To help cool the punch and die, the vacuum also is used to draw air and lubricant across the punch and into the die. A system of this general type is disclosed in Gabriel U. S. Pat. No. 3,041,905.

SUMMARY OF THE INVENTION

The general object of the present invention is to provide a new and improved vacuum collection system of the above general character which reduces the amount of work otherwise required by the punch press operator and thereby shortens the downtime of the punch press, which serves to better lubricate and cool the punch and the die and which, at the same time, better cleans the vacuum discharge so that the area around the punch press is kept pollution free.

One of the principal objects of the present invention is to empty the bin and carry the slugs away to a remote area automatically and preferably as an incident to changing the punch and die or the workpiece thereby to free the punch press operator to perform other duties.

A more detailed object is to provide means in the system for detecting a faulty vacuum seal at the bin during the punching cycle and for shutting down the press to keep the press from operating without proper vacuum in the bin.

Another primary object of the present invention is to keep the punch and the die cooler and better lubricated through the use of a mist comprising a mixture of lubricant and refrigerated air. More particularly, the foregoing is accomplished by confining the mist within a chamber which also houses the punch so that the lubricant will collect on virtually all of the exposed surfaces of the punch to keep the latter better lubricated as it reciprocates in and out of the housing during a punching cycle so that the normally heated surfaces of the punch are kept substantially cooler. By virtue of the vacuum, the mist also is drawn from the chamber and into the die thereby cooling and lubricating the exposed surfaces of the die.

The invention is characterized further by the formation of the chamber within a stripper housing, by the provision of a movable bottom wall in the bin for dumping out the slugs, by the use of a conveyor for carrying the slugs away from the bin, and by the use of a filter for cleaning the lubricant from the vacuum exhaust to avoid polluting the area around the punch press.

These and other objects and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary elevational view of a punch press embodying the novel features of the present invention and having parts broken away and shown in cross section for purposes of clarity.

FIG. 2 is an enlarged fragmentary elevational view showing parts of the press in moved positions from those of FIG. 1.

FIG. 3 is an enlarged fragmentary elevational view taken along line 3--3 of FIG. 1.

FIG. 4 is an enlarged cross-sectional view taken substantially along line 4--4 of FIG. 1.

FIG. 5 is an enlarged elevational view taken along line 5--5 of FIG. 1.

FIG. 6 is a cross-sectional view taken substantially along line 6--6 of FIG. 5.

FIG. 7 is an enlarged fragmentary elevational view taken substantially along line 7--7 of FIG. 1.

FIG. 8 is a combined schematic diagram of the electrical and fluid circuitry of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in the drawings for purposes of illustration, the present invention is embodied in a punch press 10 with a fluid-operated actuator 11 mounted on a horizontal plate 13 and operable to reciprocate a punch 14 into and out of an underlying die 15 to punch holes in an intervening workpiece 16. Herein, the punch is carried on the lower end of a ram 17 which is reciprocated by the actuator while the die is supported directly below the end of the ram within a die shoe 19, the latter in turn being supported on the bed 20 of the press by a bolster plate 21. A passage or slug chute 23 extends vertically through the bed and bolster plate from the die opening 22 and communicates with a bin 24 mounted on the underside of the bed beneath the die. The slugs (not shown) punched from the workpiece during the performance of a punching operation drop through the passage and are collected in the bin.

To help keep the slugs from possibly hanging up in the die 15 or the passage 23, the suction side of a vacuum unit 25 is connected to the bin 24 through a pipe 26 to draw the air from the bin. In operation, the slugs are sucked through the die opening 22 and the passage and into the bin. As shown in FIG. 1, the vacuum unit is connected to the pipe adjacent an inlet 27 opening into the back wall 29 of the bin. More particularly, the vacuum unit is of the vortex type wherein air is pulled from the bin and through the pipe as a result of the partial vacuum generated by forcing high pressure air into the unit and out through a discharge pipe 32 leading away from the unit. The high pressure air is delivered to the unit through an air line 33 communicating between the top of the unit and a pressure source 34 (see FIG. 8). Controlling the flow of air through the line is a solenoid valve 35 connected in the line 33 between the pressure source and the vacuum unit. To keep the slugs from possibly being sucked into the pipe 26 when the valve 36 is open, the inlet is covered by a screen 31 (see FIG. 7).

In the exemplary embodiment, the punching operation of the press 10 is numerically controlled with workpieces 16 being fed automatically into the press for punching. From time to time, the control program dictates changing the size of the punch and die set in the press in order to punch holes of different sizes in the workpieces fed into the press. This necessitates an interruption in the punching operation of the press. Similarly, the punching operation of the press may be interrupted when changing from one workpiece to another. In accordance with one of the primary aspects of the present invention, provision is made for emptying the bin 24 and carrying the slugs away automatically and as an incident to the interruption in the operation of the punch press 10. For this purpose, a door 36 in the bin is opened automatically during the interruption in the punching operation to dump the slugs onto a conveyor 37 disposed below the bin for transporting the slugs away from the bin. Thus, the operator of the punch press is not required to empty the slugs manually from the bin or to manually carry the slugs away.

In the present instance, the bin 24 (see FIGS. 2 and 3) is generally box-like in shape with a top wall 39 having a central hole 40 defining the lower end of the passage 23. The top wall is somewhat larger in area than the area outlined by the top edges of the sidewalls 41 of the bin thus leaving a peripheral flange 43 around the top of the bin. Bolts 44 extending through the flange and into the underside of the bed 20 fasten the bin to the bed, and a gasket 45 squeezed between the top wall and the underside of the bed seals the top of the bin against vacuum leaks. Extending around the periphery of the lower edge of the bin is a second or lower flange 46 and mounted on the forward edge of the lower flange is the door 36. The latter is supported along its forward end by a substantially horizontal pivot 49 to move between an open position (FIG. 2) and a closed position (FIG. 1) in which the upper or inner surface of the door engages a ring gasket 47 affixed to the underside of the lower flange to seal the bottom of the bin against vacuum leaks.

To open and close the door 36, the free end of a rod 50 is connected to the door by a bracket 51 and is reciprocable within an air cylinder 53. The head end of the cylinder is mounted pivotally above the conveyor 37 on an angle iron 55 extending between spaced legs 54 depending from the bed 20 of the punch press 10 (see FIGS. 2 and 3). As air is introduced alternatively into the ends of the cylinder through air lines 56, the rod advances and retracts to close and open the door 36. The air lines 56 connect the opposite ends of the cylinder with the pressure source 34, and a solenoid valve 57 (FIG. 8) in the air lines is controlled by signal from the numerical control to supply air to either end of the cylinder to open or close the door.

In the open position, the door 36 serves as a slide for guiding the slugs onto the conveyor 37, and generally triangular wings 59 (FIG. 2) extending upwardly from opposite side edges of the door keep the slugs from falling off the door. In addition, the back end portion 60 of the door extends rearwardly beyond the back wall 29 of the bin 24 so that, when the door is pivoted into the open position, the back end of the door fits within a chute 61. The latter funnels the slugs onto the conveyor for transportation away from the bin.

Herein, the conveyor 37 is mounted between the legs 54 of the punch press 10 and is inclined upwardly toward the rear of the press. More particularly, the conveyor comprises a frame 63 (FIG. 1) which is supported between the legs at its lower end by the angle iron 55 and adjacent its upper rear end by a similar angle iron 64. As shown in FIG. 1, the upper end of the conveyor extends past the rear of the press and overhangs a collection basket 65 to dump the slugs in the basket for subsequent collection. Journaled at the upper and lower ends of the frame are pulleys 66 and 67 about which a flexible belt 69 is trained for carrying the slugs to the basket.

To drive the belt 69, an electric motor 70 (FIG. 1) is mounted on the upper end of the frame 63 and is connected to the shaft 71 supporting the upper pulley 66 on the frame. In the present instance, a signal sent from the numerical control to initiate an interruption in the punching operation causes actuation of the motor from its normally inactive state to drive the belt. At about the same time, the solenoid valve 35 (see FIG. 8) controlling the flow of air to the vacuum unit 25 is de-actuated to turn off the vacuum in the bin 24. Subsequently, the signal from the numerical control actuates the valve 57 to retract the rod 50 into the cylinder 53 and thereby pull open the door 36 to dump the slugs onto the conveyor 63. After a predetermined period of time passes, a time delay relay 73 initially actuated by the signal from the numerical control de-actuates the motor to shut down the conveyor after the slugs have been transported and dropped into the basket 65. Thus, the bin is emptied automatically as an incident to an interruption in the punching operation of the press 10 thereby freeing the punch press operator from the task of manually emptying the bin.

Advantageously, a limit switch 74 (FIGS. 2 and 7) is mounted on the rear wall 29 of the bin 24 for engagement by the door 36 when the latter is closed in order to make sure that the door is sealed before actuation of the press 10. The switch is connected in the circuitry extending between the numerical control and a control solenoid 75 for the fluid actuator 11. When the door is open, the switch also is open and prevents the automatic cycle of the press by disabling the circuit between the numerical control and the control solenoid. As shown in FIG. 7, when the door is closed, the actuating plunger 76 of the switch is depressed to close the circuit between the solenoid 75 and the numerical control thereby to enable automatic cycling of the punch press. The switch thus prevents the press from cycling automatically if for some reason the door is open slightly and not sealed, such as might occur should the door be obstructed from closing or forced open under the weight of the slugs accumulated in the bin during an extended length of time between interruptions in the punching operation.

In the exemplary embodiment (see FIG. 1), a stripper 77 is used to strip the workpiece 16 from the punch 14 when the punch is retracted from the workpiece during the normal punching cycle of the press 10. As shown, the stripper is supported on the lower end of a generally cylindrical housing 79 which is mounted for vertical adjustment relative to the die 15 by a suitable mechanism 80 of the type disclosed in our application Ser. No. 274,391, filed July 24, 1972 and entitled Punch Press to which reference may be made for the details of the construction and the operation of the adjusting mechanism. As in the aforementioned application, the stripper includes a central opening 81 which is shaped and sized to permit the punch to pass downwardly out of the housing with each downward stroke of the ram 17 to punch a hole in the workpiece.

A door 83 (FIG. 4) forming a half-cylinder portion of the housing 79 is hinged to swing between open and closed positions about a substantially vertical axis 84 extending along one end of the door. In the closed position, the end edges of the door fit snugly against the edges of the housing to enclose the lower end of the ram 17 and the punch 14 within a chamber 85 defined by the housing 79. When opened, the door enables the operator of the press 10 to change the punch and the stripper 77 as needed for punching different shapes and sizes of holes in the workpiece 16.

Through the use of the numerical control system, the exemplary punch press 10 may be operated to do contour punching or nibbling wherein the workpiece is maneuvered under the ram 17 so that a continuous opening is punched in the workpiece 16 along a predetermined contour by punching crescent-shaped slugs from workpiece. In another type of punching operation referred to as point-to-point punching, the workpiece may be maneuvered beneath the ram and punch 14 for punching single holes in the workpiece. In this latter type of operation, a hole is punched in the workpiece at one position and the workpiece is then shifted to a second position to be punched again. Upon repeated punching at fast cycle rates such as when the numerical control commands either point-to-point punching or nibbling, the punch and die tend to become heated and by overheating may become damaged.

In accordance with another important aspect of the present invention, novel use of the housing 79 is made to keep the punch 14 and die 15 better lubricated to reduce wear and better cooling to avoid overheating. For these purposes, refrigerated air and lubricant are forced under pressure into the chamber 85 and form a cold air mist of lubricant within the chamber. Confined by the limits of the chamber, the mist better lubricates and cools the entire punch 14 to prevent overheating during normal punching operations.

In the present instance, two lines 86 (see FIG. 4) enter the chamber 85 through the walls of the stripper housing 79 from a common air line lubricator 87 (FIG. 1). The latter holds a quantity of lubricant in a single pressure line 89 which communicates between the pressure source 34 (See FIG. 8) and the two lines 86. A solenoid valve 90 in the line 89 is closed and opened in response to commands from the numerical control to prevent and to allow the air to flow into the lubricator to pick up the lubricant for spraying into the chamber. Preferably, to conserve the lubricant, the valve 90 is operated in accordance with the punching mode commanded by the numerical control. For instance, if the mode is nibbling, then the valve is set to allow a continual flow of air to the lubricator. If, however, the mode is point-to-point, the valve is operated normally to open and close during repositioning the workpiece remaining open for a predetermined period of time as the workpiece 16 is being moved from point to point.

As shown in FIGS. 1 and 4, the two lubricant lines 86, enter the housing 79 at positions spaced from each other at an included angle relative to the central axis of the ram 17 of about 150°. The two lines include outlets defined by nozzles 91 extending through the wall of the housing and slanting downwardly generally toward the stripper 77 to direct the spray of liquid at opposite sides of the lower end of the punch 14 when the latter is retracted within the housing. With this arrangement, a swirling flow is imparted to the lubricant mist as it is sprayed into the chamber 85 so that all exposed surfaces of the punch are kept well lubricated for punching.

To cool the punch, a cold air hose 93 enters the chamber 85 through the housing 79 between the two nozzles 91 at approximately the same vertical position above the stripper 77 as the nozzles. More particularly, the nozzle 92 of the cold air hose is located at a position angularly spaced at about 70 degrees from the closest nozzle 91. Also, the nozzle 92 is slanted downwardly toward the stripper at an angle similar to that of each of the nozzles 91 to direct the cold air onto the punch 14 and to help impart the swirling flow to the mist which includes both the refrigerated air and the sprayed lubricant.

The inlet end of the cold air hose 93 connects with a refrigeration unit 94 which is mounted on the punch press 10 behind the fluid actuator 11. An air line 95 (see FIG. 8) connected between the refrigeration unit and the pressure source 34 delivers air under pressure to the unit for cooling. A solenoid valve 96 connected in the line 95 between the refrigeration unit and the source is opened and closed on command from the numerical control to permit the flow of refrigerated air through the hose and into the chamber 85 for cooling the punch during the punching operation.

In addition to keeping the punch 14 from overheating, the combined cold air and lubricant escaping from the housing 79 also cools and lubricates the die 15. Upon passing through the opening 81 in the stripper 77, the mist is captured by the vacuum in the die opening 22 and is drawn across the exposed surfaces of the die to keep such surfaces from overheating and experiencing excessive wear.

By virtue of the combined action of the chamber 85 in comfining the mist around the lower end of the ram 17 and of the vacuum in drawing the escaping mist into the die 15, the present arrangement also advantageously avoids pollution of the immediate punching area with the lubricant during the actual punching operation. The excess lubricant which passes through the die 15 is sucked through the bin 24 and into the pipe 26 by the vacuum unit 25. To avoid pollution of the immediate punching area when the door 85 is opened to change the punch 14, provision is made for purging the chamber 85 of the mist prior to opening the door. This is accomplished by forcing clean air into the top of the chamber to drive the remaining mist out of the chamber through the opening 81 after the flow of lubricant into the chamber has been halted but before the vacuum has been turned off. As shown in FIG. 8, a small conduit 104 is connected with the pressure source through a solenoid valve 105 and with the chamber 85 through the wall of the housing 79 adjacent the adjusting mechanism 80. The conduit directs clean air into the chamber when the valve is opened in response to a command from the numerical control to purge the chamber of the polluting mist.

To prevent lubricant drawn through the vacuum unit 25 from being exhausted back into the air, a filter box 97 is connected at the discharge end 98 of the pipe 32 to separate the lubricant from the exhaust air. As shown in FIG. 1, the filter box is mounted on the back of the press 10 with the discharge end of the pipe connected to the front of the box to direct the exhaust air into a lower chamber 99 (see FIGS. 5 and 6) within the box. Two industrial-type filters 100 define the top of the chamber and are formed of steel mesh to separate dirt and grease from the exhaust air. A curved hood 101 on the top of the box directs the filtered air back into the atmosphere through a generally rectangular opening 103 in the front side of the box.

In the exemplary embodiment, command signals from the numerical control are used to initiate the operation of all the solenoid valves 35, 57, 90, 96 and 105 as well as the operation of the conveyor motor 70. Thus, for instance, upon receiving the command to change the punch and die set, the solenoid valves 90 and 96 are closed to stop the flow of refrigerated air and lubricant into the housing 79. At the same time, the solenoid valve 105 is opened to purge the chamber 85 of lingering mist. Upon receipt of a second command, the valves 35 and 105 are closed to turn off the vacuum and the purge air. Coincidentally therewith, the conveyor motor 70 is actuated to drive the belt 69 and, after a brief delay, a third command causes the valve 57 to operate the cylinder 53 to open the bin door 36 to dump the slugs onto the moving belt. The time delay relay 73 keeps the motor running long enough for slugs to be delivered into the basket 65 and then the motor is shut off to stop further movement of the belt. Once the change of the punch and die set is completed, the operator depresses a cycle start button (not shown) initiating a second set of command signals to reverse the solenoid valves 57, 35, 90 and 96. If the bin door seals closed properly to hold the vacuum, the punching cycle is ready to continue after the solenoid valves assume their normal operating positions.

While the present invention has been described herein as used in a punch press 10 with numerical control system, it will be appreciated that the unique features of the present invention may be employed with equal advantage in a manually operated punch press. In fact, this is exemplified in the present punch press control arrangement through the use of a manual control 106 (FIG. 8) whereby the numerical control system may be overridden by the punch press operator to produce signals to simulate certain of the commands of numerical control. In particular, the manual control may be used to energize the time delay relay 73 to start the conveyor 37 and to operate the valve 57 to open the bin door 36.