Abstract:
A safety interlock and retraction mechanism for all types of presses comprising a sensing or activating valve which does not apply full force to a press ram until the ram displaces to the expected work material thickness and a pneumatically operated retraction mechanism which eliminates the need for a return spring. The art differentiates between the thickness of an operator&#39;s finger relative to a work material thickness in order to promote safety. The art further provides an increased press ram force by eliminating the return spring force subtracting from the ram force.

Description:
This application claims priority of U.S. Provisional Patent Application No. 60/570,764, filed May 14, 2004. 

   BACKGROUND OF THE INVENTION 
   The present invention relates in general to safety and retraction mechanisms for presses. More specifically, the mechanism of this invention represents a unique safety interlock and retraction mechanism for clinching, crimping and punching presses, especially those presses as described in U.S. Pat. No. 5,937,694 issued to Mueller on Aug. 17, 1999. The aforesaid U.S. Pat. No. 5,937,694 issued to Mueller is hereby incorporated by reference. Many prior art presses as described in Mueller utilize one or more return springs to retract the ram from the work material and do not offer a safety interlock mechanism. When the aforesaid return spring(s) is used, the actuator must present a force upon the cams and cam rollers greater than the compressed spring force in order to actuate the ram toward the work material. Unfortunately, this results in less force upon the work material since the spring force must be overcome. Utilization of a return spring further limits the ram displacement due to the limitation on spring length within the fixed size frame and may also limit the ram retraction rate. 
   The present art represents an air cylinder retraction mechanism which eliminates the requirement for a return spring and further provides an interlock feature which prohibits full force actuation unless the desired work material having a predetermined thickness range is placed between a punch and die of the press. That is, the present art utilizes one or more pneumatic actuators having an internal return mechanism or spring and a pneumatic valve which allows only a nominal pneumatic actuator return force application to the ram unless the ram displacement is sufficient to indicate that a thinner or predetermined thickness of work material is between the punch and die and not a thicker material such as an operator&#39;s finger. 
   Accordingly, it is an object of the present invention to provide a press retraction mechanism apparatus and method of use which ensures safety and eliminates the need for a return spring to retract the ram from the work material. 
   Another object of the present invention is to provide a safety interlock apparatus and method of use which prohibits full force actuation of the press unless a predetermined thickness range of desired work material is placed between a punch and die of the press. 
   A further object of the present invention is to provide a safety interlock and retraction mechanism apparatus and method of use which provides an increased force upon the work material due to the absence of a counteracting return spring force. 
   A yet further object of the present invention is to provide a safety interlock and retraction mechanism apparatus and method of use which does not suffer the prior art limitations of ram displacement. 
   SUMMARY OF THE INVENTION 
   To accomplish the foregoing and other objects of this invention there is provided a safety interlock and retraction mechanism for presses in general and specifically clinching, crimping and punching presses. The safety interlock and retraction mechanism comprises one or more pneumatic cylinders attached to the press; a control valve, an activating valve having two or more ports and an activating button; and an air piloted valve capable of directing pneumatic air flow such that full force actuation is prohibited unless the work material has a predetermined thickness range, thereby allowing activation of the pneumatic valve. Preferably, the safety interlock and retraction mechanism is attached to a pneumatic press such that an existing shop air supply, existing air stroke actuator or air bag, and existing foot operated multi-port pneumatic valve can be utilized and incorporated into the present safety interlock and retraction mechanism. 
   In the preferred embodiment, the one or more pneumatic cylinders have a housing and a spring biased extension rod. The housing of the one or more pneumatic cylinders attaches intermediate the existing ram and cam roller housing; and the extension rod attaches through a plate to the frame of the press. 
   The one or more pneumatic cylinders are pneumatically connected such that when the existing foot operated pneumatic valve is depressed, the pressurized air supply to the one or more cylinders is essentially eliminated. This allows the spring biased extension rods to retract and allows the ram to partially close under only the force of the one or more cylinder spring biases. If the work material is within a predetermined thickness range, mechanical depression of the activating button of the pneumatic valve occurs and activates the humphrey or air piloted valve. Once activated, the air piloted valve allows compressed air flow to the air stroke actuator for full force activation. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Numerous other objects, features, and advantages of the invention should now become apparent upon a reading of the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1A  is a right side plan view of the prior art Mueller improved clinching, crimping and punching press with the ram in an open position and the air stroke actuator un-pressurized. The right side plan view is symmetric with the left side plan view. 
       FIG. 1B  is a right side plan view of the prior art Mueller improved clinching, crimping and punching press with the present art safety interlock and retraction mechanism. 
       FIG. 2  shows a perspective view of the safety interlock and retraction mechanism with attached ram. 
       FIG. 3  shows a front side plan view of the safety interlock and retraction mechanism with attached ram. 
       FIG. 4  shows a left side plan view of the safety interlock and retraction mechanism with attached ram. 
       FIG. 5  shows a top side plan view of the safety interlock and retraction mechanism with attached ram. 
       FIG. 6  shows an assembled left side perspective view of the safety interlock and retraction mechanism attached with the ram and press of Mueller. 
       FIG. 7  shows a pneumatic schematic diagram of the pneumatic supply to the valves, cylinders, air stroke actuator (air bag), and other components. Equivalent parts listed may be substituted from other manufacturers. 
   

   DETAILED DESCRIPTION 
   Referring now to the drawings, a preferred embodiment of the safety interlock and retraction mechanism for clinching, crimping and punching presses is shown in  FIGS. 1A–7 . The safety interlock and retraction mechanism  10  is described in conjunction with a prior art pneumatic press  110  for clinching, crimping and punching including but not limited to that described in U.S. Pat. No. 5,937,694 issued to Mueller on Aug. 17, 1999. The present art is also usable with and for other types of presses, including but not limited to hydraulic, electric, or mechanically actuated presses. 
     FIG. 1B  of the drawings, shows the safety interlock and retraction mechanism  10  for clinching, crimping, and punching presses in combination with the prior art pneumatic press  110  of Mueller. The safety interlock and retraction mechanism  10  of the present invention is preferably interconnected with the pneumatic system of the prior art pneumatic press  110  and operates pneumatically. Alternative embodiments may utilize hydraulic, electrical, or mechanical techniques to operate the present art apparatus  10 . The pneumatic system of the prior art, in part, primarily consists of a pneumatic air supply  111 , an air stroke actuator  112  or air bag, a pneumatic valve  66  with a foot operated lever  67 , such as a Numatic® model NAM500100 or its equivalent. The air stroke actuator  112  when fully activated moves a rolling cam  129  which in turn moves a second cam roller  122  connected to a cam roller housing  124  and a ram  126 . 
   The safety interlock and retraction mechanism  10  comprises one or more pneumatic actuators or cylinders  12  attached with the pneumatic press  110 ; a push button pneumatic actuating valve  46  having at least a first port  53 , a second port  54 , and an activating button  48 ; and an air piloted valve  60  having at least a first port  62 , a second port  63 , and an actuating port  61  which are all controlled by a control valve  66 . The air piloted valve  60  in conjunction with said pneumatic activating valve  46  is capable of directing pneumatic air flow such that full force actuation is prohibited unless the work material is within a predetermined thickness range. That is, if the internal biasing of the pneumatic actuators or cylinders  12  moves the press ram  126  sufficiently to activate said activating valve  46 , said air piloted valve  60  is activated and full pneumatic pressure is supplied to said air stroke actuator  112 . 
   The one or more pneumatic actuators or cylinders  12  preferably have a housing  13  with a first end  14  and a second end  15 , and a spring biased extension rod  17 . The housing(s)  13  of the one or more pneumatic cylinders  12  preferably attach intermediate the ram  126  and the cam roller housing  124  and the extension rod  17  attaches to a frame  116  of the press  110 . 
   The one or more pneumatic cylinders  12  are activated or pneumatically connected when the foot operated pneumatic valve  66  is depressed. The pneumatic supply  111  to the one or more cylinders  12  is essentially eliminated when foot operated pneumatic valve  66  is released. This causes the spring biased extension rods  17  to retract and thereby allows the ram  126  to partially close under only the force of the one or more cylinders  12  spring bias. If the work material is within the predetermined thickness range, thereby allowing mechanical depression of the activating button  48  of the pneumatic activating valve  46 , the air piloted valve  60  allows compressed air to flow to the air stroke actuator  112  for full force activation. 
   In a preferred embodiment, the present art first comprises two pneumatic cylinders  12 , each preferably a Bimba® model 092 and/or a Clippard®model SSR-17-2 or their equivalents. Alternative embodiments may utilize one or more than two of the aforesaid cylinders  12 . The preferred embodiment further comprises a ram mounting plate  21  having a first end  22  and second end  23 , a topside  24 , and a bottomside  25 . The second end  23  of the housing  13  of each of the one or more pneumatic cylinders  12  is mounted onto said ram mounting plate  21 , preferably at or near said first end  22  and said second end  23  and onto said topside  24 . Said housing  13  of said one or more pneumatic cylinders  12  is preferably mounted through holes  26  within said plate  21  via threads and nuts  29  on said housings  13  but may be mounted with alternative means including but not limited to brackets, bolts, rivets, welds, or screws. The ram mounting plate  21  is preferably mounted onto the press  110  between the cam roller housing  124  as described in Mueller and the ram  126  as also described in Mueller. Preferably said ram mounting plate  21  mounting is via a hole  28  in said ram mounting plate  21  through which a bolt attaches into or through said cam roller housing  124  and through said ram mounting plate  21  and thereafter engages threads within said ram  126  to form a sandwich. That is, said ram mounting plate  21  is sandwiched between said cam roller housing  124  and said ram  126 . Alternative embodiments may attach the ram mounting plate  21  to said ram  126  or cam roller housing  124  via a plurality of means including but not limited to brackets, bolts, rivets, welds, or screws, provided said plate  21  displaces with said ram. 
   Each of said one or more pneumatic cylinders  12  has an extension rod  17  which extends from the second end  15  of each cylinder housing  13  when each of the one or more pneumatic cylinders  12  is pneumatically activated or pressurized. In a preferred embodiment, said extension rods  17  are at least partially threaded for attachment to a frame plate  32 , near or at a first end  34  or a second end  36  of said frame plate  32 . Alternative embodiments could attach said extension rods  17  to the frame plate  32  in a plurality of ways, including but not limited to brackets, bolts, rivets, welds, or screws. 
   The frame plate  32  has a top side  38 , bottom side  40 , a first end  34 , a second end  36 , and in a preferred embodiment one or more threaded holes  42  near said first end  34  or said second end  36  for mounting said extension rods  17 . Alternative embodiments may attach said extension rods  17  to said frame plate  32  with a plurality of means including but not limited to brackets, bolts, rivets, welds, or screws. The frame plate  32  preferably mounts onto or with the frame  116  as described in Mueller near the intersection of the ram  126  and the bored hole  144  of Mueller with said bottom side  40  resting on the press frame  116  within the first opening  140 . Typically this is with threaded fasteners  29  through one or more holes  44  through said frame plate  32  and into said frame  116 . The frame plate  32  serves as a substantially non-moving mounting platform for the safety interlock and retraction mechanism  10 . In a preferred embodiment, said frame plate  32  is held via one or more bolts, preferably two, which are threaded through said frame  116  and mechanically bind over said top side  38  of the frame mounting plate  32 . Also in a preferred embodiment, the frame plate  32  has a notched portion  41  through which the ram  126  is able to clear and extend. Alternative embodiments may forego use of said notched portion  41  for ram clearance and instead shape and position the frame plate  32  in a manner which will not interfere with ram  126  movement. Alternative embodiments may further attach the frame plate  32  in a plurality of rigid or floating ways including but not limited to brackets, bolts, rivets, welds, or screws. 
   Onto the frame plate  32  is attached a push button pneumatic activating valve  46 , preferably a Pneumadyne® model C021605 or equivalent, which extends away from the top side  38  of the frame plate  32  toward or parallel with the housing  13  of one of the one or more pneumatic cylinders  12 . Said pneumatic valve  46  has a valve body  49  and button end  50  with an activating button  48 , said activating button  48  serving as the actuating portion of the pneumatic valve  46 . When mounted, the button end  50  preferably extends toward or parallel with the housing  13  of one of the one or more pneumatic cylinders  12 . Preferably the pneumatic valve  46  is mounted with a small “L-shaped” bracket  55  onto the frame plate  32  and further has an attached overstroke operator  56  such as a Pneumadyne® model POSA or equivalent attached onto the button end of the pneumatic valve. The overstroke operator  56  or actuator is understood by one skilled in the art as a spring loaded attachment which allows activation of the pneumatic valve  46  activating button  48  and further allows continued displacement against its spring loading. Typically the continued displacement or overstroke is approximately 0.73 inches yet may vary in alternative embodiments. It is important to note that alternative embodiments may position the valve activating button  50  such that utilization of the overstroke operator  56  is not required or position the pneumatic valve  46  in a plurality of positions on or off of the frame  116  of the press  110  in Mueller. 
   The push button pneumatic valve  46  typically has two ports, a first port  53  which is normally closed and a second port  54  which is vented to atmosphere when the pneumatic valve  46  is not actuated. Upon actuation or activation, by pressing the activating button  48 , the pneumatic valve  46  forms a continuous pneumatic path between the first port  53  and the second port  54  without atmospheric venting. 
   In the preferred embodiment, the overstroke operator  56  touches with a clamp  19  or arm extending from the housing  13  of said one of the one or more pneumatic cylinders  12  when the cylinder extension rods  17  are retracted. This clamp  19  or arm thereby actuates the pneumatic valve  46  and creates a continuous pneumatic path between the first port  53  and the second port  54  without atmospheric venting. Said clamp or arm  19  may also extend from components attached to said ram  126  such as the ram mounting plate  21  or the ram  126  itself. 
   In the preferred embodiment, the second port  54  of the pneumatic valve  46  is connected to an air piloted valve  60 ; preferably a three way air pilot operated valve by Humphrey® with model number 250A31020 or equivalent (hereafter a humphrey valve), and the first port  53  is connected to the pneumatic supply  111  through a second port  72  of a pneumatic footswitch control valve  66 . That is, when the foot operated lever  67  or footwitch control valve  66 , is depressed, a pressurized pneumatic supply  111  is provided to the first port of the pneumatic valve  46 . Unless the pneumatic valve  46  is actuated via the clamp or arm  19  extending from the housing  13  of said one of the one or more pneumatic cylinders  12 , the compressed air supply  111  cannot flow to an actuating port  61  of the air piloted valve  60  (humphrey valve). The air piloted valve  60  (humphrey valve) is understood by those skilled in the art as a pneumatically actuated valve. The air piloted valve  60  (humphrey valve) has an actuating port  61 , a first input port  62 , and a second output port  63 . Unless compressed air is supplied to the actuating port  61 , the first input port  62  is closed and the second output port  63  is vented to atmosphere. When compressed air is supplied to the actuating port  61 , the first input port  62  and the second output port  63  forms a continuous pneumatic path between the first input port  62  and the second output port  63  without atmospheric venting. In the preferred embodiment, the same pneumatic or air supply  111  from the footswitch pneumatic valve  66  having with the foot operated lever  67  is connected with the first port  53  of the pneumatic valve  46  and is also connected with the first input port  62  of the air piloted valve  60  (humphrey valve). The second output port  63  of the air piloted valve  60  (humphrey valve) is connected with the air stroke actuator  112  or air bag of the Mueller press  110  or equivalent. Thus, upon activation of the foot operated lever  67 , compressed air cannot be supplied to the air stroke actuator  112  or air bag unless the pneumatic valve  46  is actuated via the clamp or arm  19  extending from a housing  13  of the one or more pneumatic cylinders  12 . This assures that the ram  126  reaches or creates a distance between the ram  126  punch and die which clearly indicates that a thin sheet metal workpiece or equivalent predetermined material thickness is between the ram  126  punch and die rather than a thicker object such as an operator&#39;s finger, before the air stroke actuator  112  or air bag is pressurized. 
   The footswitch pneumatic control valve  66  contains an input pneumatic pressurization port  68 , a first output port  70 , a second output port  72 , and a foot operated lever  67 . Each output port  70 ,  72  is alternatively vented to atmosphere or connected with said input port  68  depending on whether the foot operated lever  67  is depressed. That is, when the foot operated lever  67  is not depressed, compressed air flows out of the second output port  72  to the one or more pneumatic cylinders  12 , thereby causing said extension rods  17  to extend. Extension of said extension rods  17  forces quick retraction of the press ram  126 . When the foot operated lever  67  is depressed, the one or more pneumatic cylinders  12  are vented to atmosphere and the pneumatic activating valve&#39;s  46  first port  53  and the air piloted valve&#39;s  60  (humphrey valve) first input port  62  are supplied with compressed air from the first output port  70  of the pneumatic control valve  66 . Since the extension rods  17  of the one or more pneumatic cylinders  12  are biased to retract, typically with spring loading, the ram  126  begins movement thereby moving the punch and die closer. This occurs since the ram mounting plate  21  is attached with the ram  126  and the frame plate  32  is held with the frame  116  as aforedescribed. Thus, the only force upon the ram  126  is the return mechanism or springs of the one or more pneumatic cylinders  12  until such time as the pneumatic activating valve  46  allows the air piloted valve  60  (Humphrey valve) to supply pneumatic pressure to the air stroke actuator or air bag  112 . Moreover, until the pneumatic activating valve  46  is actuated via engagement with the clamp or arm  19  extending from a housing  13  of said one or more pneumatic cylinders  12 , compressed air is not supplied to the air stroke actuator or air bag  112 . This assures that dangerous levels of force are not applied to the punch and die combination until the ram  126  is displaced sufficiently to indicate that an operator&#39;s finger is not present. 
   The clamp or arm  19  extending from the housing  13  of said one or more pneumatic cylinders  12  is typically adjustable in elevation via a setscrew or clamping bolt  20 . This provides a method by which the operator may adjustably obtain an optimum distance between the punch and die before maximum force is applied to the ram  126 . 
   Although description of the pneumatic schematic has been provided in conjunction with the aforesaid mechanical components, description of the pneumatic interconnections is desirable for clarity. As seen in the figures, a pneumatic compressed air supply  79  is provided to a pneumatic control valve  66  which feeds said compressed air supply  79  to the press  110  and safety interlock and retraction mechanism  10 . The first output port  70  of the pneumatic control valve  66  vents the pneumatic line feeding the pneumatic activating valve  46  and the air piloted valve  60  (Humphrey valve) when the foot operated lever  67  is not depressed. The second output port  72  of the pneumatic control valve  66  also connects the pneumatic supply  79  to the line feeding the one or more pneumatic cylinders  12  when the the foot operated lever  67  is not depressed. This assures that the extension rods  17  from the one or more pneumatic cylinders  12  extend and thereby raise the ram  126  when the foot operated lever  67  is not depressed. That is, instead of utilizing springs to return the ram  126  after a clinching, crimping, or punching operation, the ram  126  is returned or retracted via the force of the one or more pneumatic cylinders  12 . 
   When the foot operated lever  67  is depressed, the second output port  72  is vented to atmosphere and the first output port  70  is connected with the pneumatic supply  111  thereby feeding the pneumatic valve  46  and the air piloted valve  60  (Humphrey valve). Until and unless the biased retraction mechanism or springs of the one or more pneumatic cylinders  12  move the ram  126  sufficiently toward the work material whereby the arm  19  may activate the pneumatic activating valve  46  thereby activating the air piloted valve  60  (Humphrey valve), the compressed air supply  111  is withheld from the air stroke actuator  112  or air bag. That is, the second output port  63  of the air piloted valve  60  (Humphrey valve) is connected with said air stroke actuator  112 . As aforesaid, sufficient force for crimping, clinching, and punching cannot be provided until said air stroke actuator  112  is pressurized via activation of the air piloted valve  60  (Humphrey valve). 
   Included within the present art apparatus  10  alternative embodiments are one or more quick exhaust valves  74 . In the preferred embodiment, three quick exhaust valves  74  are used. One quick exhaust valve  74 , preferably by Humphrey® with model number QE2 or equivalent, is pneumatically connected near the air stroke actuator or air bag  112 . The remaining two quick exhaust valves  74 , preferably by Clippard® with model number JEVF-2F2 or equivalent, are pneumatically connected near each of the two pneumatic actuators or air cylinders  12  of the preferred embodiment. A quick exhaust valve  74  typically has an input port  75  and an output port  76 . When the input port  75  is pressurized, a connection is formed between the input port  75  and output port  76 . When the input port  75  is vented to atmosphere, the output port  76  is also vented to atmosphere at the location of the quick exhaust valve  74  and not only through the input port  75 . The pneumatic schematic diagram shows inline pneumatic placement of the one or more quick exhaust valves  74  within the lines feeding each of the air cylinders  12  and the line feeding the air stroke actuator or air bag  112 . Utilization of the quick exhaust valves  74  assures quick venting of the aforesaid components, thereby allowing for faster operation of the present art. 
   In operation, a user or technician first adjusts the arm or clamp  19  location for the thickness of work material to be utilized. The user then places a work material between the punch and die of the press  110  and depresses the foot operated lever  67 . The biased return mechanism within the one or more pneumatic cylinders  12  forces the ram  126  to move the punch and die towards each other. When the ram  126  displacement is sufficient to indicate that a proper thickness work material is present, the pneumatic valve  46  actuates the air piloted valve  60  (Humphrey valve), thereby providing compressed air to the air stroke actuator  112 . Upon activation of the air stroke actuator  112 , full press force is applied to the punch and die. Upon user release of the foot operated lever  67 , the air piloted valve  60  (Humphrey valve) is deactivated, the air stroke actuator or air bag  112  is vented to atmosphere, and the one or more pneumatic cylinders  12  are pressurized, thereby quickly retracting the ram  126 . 
   For all of the aforesaid pneumatic devices, a pneumatic source  79  is presumed available and able to feed each of the aforesaid components. The aforesaid press  110  and frame  116  as described in Mueller and associated components may be manufactured from a variety of materials including but not limited to metals and alloys thereof, plastics, and composites. Where described, part numbers and manufacturer&#39;s names are included for informational and enablement purposes only. Other substantially equivalent brand and part numbers may be substituted without departing from the scope and spirit of the present application. This includes but is not limited to substitution of manual, electronic, hydraulic, or pneumatically controlled components and control valves for the pneumatic control valve  66  and other pneumatic components. As understood within the art, when a port or output of an element is activated, a supply of compressed air, hydraulic fluid, electrical energy, or mechanical force is supplied from said element. This supply is dependent upon whether the valve or actuator is designed for compressed air, hydraulic fluid, electrical energy, or mechanical force respectively. Combinational valves including but not limited to electro-pneumatic and electro-hydraulic valves may further be utilized within the present art. 
   From the foregoing description those skilled in the art will appreciate that all objects of the present invention are realized. A safety interlock and retraction mechanism  10  apparatus and method of use has been shown and described. The apparatus and method of use provides a safety interlock which prohibits full force actuation of the press unless the desired work material having a predetermined thickness range is placed between a punch and die of the press. This feature is especially useful for distinguishing between a work material and an operators finger. The apparatus and method of use also provides a press retraction mechanism which eliminates the need for a return spring for ram retraction from the work material thereby providing more force and ram displacement onto and at the work material. 
   The preferred design of the present invention as well as alterations that will now be apparent to those skilled in the art all allow use of the safety interlock and retraction mechanism with any press. The present invention and the alternative embodiments, are available in and adaptable to a variety of shapes, forms, and sizes. 
   Having described the invention in detail, those skilled in the art will appreciate that modifications may be made of the invention without departing from its spirit. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described. Rather it is intended that the scope of this invention be determined by the appended claims and their equivalents.