Patent Publication Number: US-8984922-B2

Title: Method of and apparatus for positioning a tool

Description:
The invention relates to a method of and apparatus for positioning a tool in a profile rolling machine. 
     PRIOR ART 
     In case of profile rolling machines, in particular screwthread rolling machines, a blank is processed between two tools and by rolling the blank on the profile-generating contact surfaces of the tools, the profile, for example a screwthread, is formed on the blank. During this process, a significant pressure is exerted between the tools and the blank. Here, the blank can gets caught between the tools and cannot be released simply by moving the tools back and forth in the apparatus. The clamping pressure is so high that even the machine drive can no longer move a slide with the tool for opening and/or damages the tools due to the bending occurring here. In order to release the blank from the tool, usually, a high leverage force has to be applied, or the tool or even other components within the installation have to be disassembled. This is very time-consuming and can result in damage to the machine. Moreover, after disassembling the tools, they have to be reassembled and adjusted. 
     DESCRIPTION OF THE INVENTION 
     It is the object of the invention to provide a method of and apparatus for positioning a tool in a profile rolling machine that allow a fast and easy opening as well as a fast repositioning of the rolling tool into its starting position. Moreover, cost effectiveness and safety of the installation is to be improved. 
     This object is solved by an apparatus for positioning a tool in a profile rolling machine comprising a base configured to have at least one first bore, and at least one adjusting spindle having a tool stop, which adjusting spindle is mounted in a position-variable manner in the first bore of the base. A retraction rod is adjustable as to position for positioning the first tool with a tractive force against the tool stop. The first bore is locally expanded to form a cylinder chamber. A piston can move axially in this cylinder chamber. The piston and the cylinder chamber together form a piston-cylinder unit. A pressure connection is provided in the base for introducing a pressure medium with a first pressure into the cylinder chamber between the base and a back piston face directed away from the first tool. Alternatively, instead of the pressure connection, a vacuum connection is provided in the base for introducing a vacuum into the chamber between a piston front face directed toward the tool and the base. 
     Thus, an apparatus is provided in a profile rolling machine by means of which at least the tools can be opened in a fast and easy manner by the position-variable piston, and after removing the blank from the apparatus, the tool can be repositioned with the piston and adjusting spindle connected thereto into its starting position without the need to carry out complicated adjustment and calibration work. For example in case of damage or during maintenance work on the apparatus, significant time is saved by the apparatus according to the invention. The easy opening of the tool with the position-variable piston ensures a gentle method for releasing the apparatus without additional levers or mechanical impacts that, in the worst case, can result in damage or destruction of the tool or the apparatus. The cost effectiveness and safety of the installation are considerably improved over the prior art. 
     The constructional alternative of the vacuum connection instead of the pressure connection in the base provides advantageously an alternative possibility of applying force to the piston that can be used in case of failure of the pressure for changing the position of the piston. 
     In a first configuration of the invention the adjusting spindle is mounted in a third bore in the piston such that it can change its position axially of the piston. The adjusting spindle serves as abutment for the first tool and due to this arrangement, can change its position in a simple and fast manner. 
     Furthermore, the invention provides that the adjusting spindle and the piston are connected to each other by a screwthread. In this manner, the adjusting spindle can easily be displaced and precisely adjusted or positioned in the right position as tool stop for the tool. 
     In a further preferred embodiment of the apparatus according to the invention a controller is provided for applying a first pressure for the pressure medium or for applying the vacuum in the chamber, depending on the material and the dimensions of the blank to be rolled. This way it is possible to quickly and flexibly adjust the compression pressure of the tool against a blank. The positioning force of the tool can be adjusted with the control in a simple and accurate as well as fast and flexible manner. With respect to the necessary positioning or pressing forces, the apparatus can be set for many different materials such as stainless steels, standard steels, high-strength steels, nonferrous metals or plastics with different dimensions. Complicated recalibrating is not required so set-up times are significantly reduced. 
     Furthermore, the invention provides that the controller is configured for controlling the actuator and thus for setting the amount of tractive force on the retraction rod depending on the first pressure or the vacuum in the chamber. As a result, a simple and reliable possibility for positioning or opening the apparatus is provided, wherein, depending on the material properties of the blank to be processed and the blank dimensions, the forces acting on the piston and the retraction rod can be very accurately adapted to each other. 
     In a further configuration of the invention, the piston is provided on its front face directed toward the tool with a first projecting sleeve that is mounted in the first bore in the base, and/or the piston is equipped on its back face directed away from the tool with a second projecting sleeve that is likewise mounted in another section of the first bore in the base. With this arrangement according to the invention, additional guidance and stable mounting for the piston is created that is in particular advantageous in case of very high forces or long stokes. 
     In a preferred embodiment of the invention the profile rolling machine is configured as a thread rolling machine. 
     The method according to the invention for operating the apparatus described above comprises the following steps: 
     positioning the piston and the adjusting spindle connected thereto and having a tool stop by displacing the piston in the cylinder chamber by introducing a pressure medium into the chamber with a first pressure that generates a force on the piston&#39;s back face directed away from the tool such that the piston is displaced against a first abutment of the housing, or by a suction force that acts on the piston and is generated by introducing a vacuum into the chamber between a piston front face directed toward the tool and the base, and 
     pulling the tool against the tool stop by the retraction rod with a tractive force that is generated by the actuator, the tractive force being smaller than the first force or smaller than the suction force and counteracting same. 
     In a first configuration of the method the tool stop is positioned and adjusted by axially displacing the adjusting spindle in the third bore of the piston. 
     In a further configuration of the invention, the method according to the invention provides that the adjusting spindle is axially displaced by a screwthread in the third bore. This method step allows a fine adjustment or fine positioning of the tool stop with respect to the previous prepositioning of the tool stop carried out by the piston. 
     Preferably, the method provides that the controller establishes the first pressure of the pressure medium or the suction force by the vacuum in the chamber and the tractive force applied on the feed spindle to respective predefined values that are each predefined depending on the material and the dimensions of a blank to be shaped. 
     In one configuration of the method the profile rolling machine can be a thread rolling machine and a screwthread or profile is rolled into the blank. 
     The method further provides that for releasing or opening the tool, the first force of the pressure medium or the vacuum is reduced or decreased close to zero and the tractive force generated by the actuator and acting on the retraction rod becomes greater than the first force generated by the first pressure or suction force acting on the piston. After force application with the tractive force, the retraction rod with the tool and the adjusting spindle with the piston move together in a rearward direction away from the tool. 
     Further advantages and details of the invention arise from the sub-claims and the following description in which the embodiments of the invention illustrated in the figures are explained in more detail. Apart from the above-described combinations of features, the features are also essential for the invention as individual features or in other combinations. 
    
    
     
       DESCRIPTION OF THE FIGURES 
       The invention is described in detail hereinafter with reference to  FIGS. 1 to 5 . Therein: 
         FIG. 1  shows the apparatus during profile rolling in an adjustment position closed on the blank; 
         FIG. 2  shows the apparatus after profile rolling in an open position relative to the blank; 
         FIG. 3  is a side view of the apparatus; 
         FIG. 4  shows an alternative embodiment of a piston in the apparatus, the apparatus being shown in an adjustment position closed on the blank. 
         FIGS. 5   a - 5   e  show the operation of the apparatus. 
     
    
    
       FIG. 1  shows an apparatus  100  for positioning a tool  21  in a profile rolling machine. A base  10  has at least one first bore  17  through which extends an adjusting spindle  30  having a front end forming a tool stop  23 . The spindle  30  has a rear part  38  axially slidable in the first bore  17  of the base  10 . A retraction rod  25  is axially shiftable for applying to a movable tool  21  an axial rearward retraction force F 2  relative to an axially fixed tool or die  22  and against the stop  23 . In this retracted position the tool  21  bears axially rearward against a front face  24  of the tool stop  23  of the adjusting spindle  30 . Preferably, the retraction rod  25  extends through a second bore  28  in the base  10 . The second bore  28  also serves as a guide for the retraction rod  25 . 
     The retraction rod  25  is connected to the tool  21  by a first connection  26 , here a T-head mounted in a guide groove  27 . In this embodiment, the tool  21  can easily be mounted as an exchangeable part on the retraction rod  25 . To this end, the T-head  26  is simply slid into the guide groove  27 . Alternatively, a simple screw or pin between the tool  21  and the retraction rod  25  can also be selected or the retraction rod  25  can be directly connected to the tool  21  by a weld. 
     The axially rearwardly directed tractive force F 2  acting on the retraction rod  25  in a direction away from the tool  21  is generated by an actuator  50 . The actuator  50  is preferably connected to the base  10 , but can also be attached to the base frame of the profile rolling machine or, for example, to a separate mounting frame. The actuator  50  is usually a fluid-powered piston-cylinder unit powered by air, oil or hydraulic fluid, but, alternatively, can also be a spring, for example a compression spring, or elastomeric body. 
     In a further embodiment the retraction rod  25  is connected first to a tool support  20  as adapter between the retraction rod  25  and the tool  21  and to fasten the tool  21  as detachable or exchangeable attachment part, for example by a screw connection, to the tool support  20 . In this manner, the apparatus can easily be adapted to different tasks and loads of the profile rolling process, for example by using reinforced tool supports  20  or different tools  21  as exchangeable parts in the apparatus. 
     The first bore  17  has a region of enlarged diameter toward its front rear end and forms a cylindrical chamber  12  surrounding the spindle  30 . A piston  40  surrounding the spindle  30  can shift axially in the enlarged chamber  12 . The cylindrical chamber  12  and the piston  40  form a piston-cylinder unit. The first bore  17  and the chamber  12  can be formed directly in the base  10  or, alternatively, as illustrated in a partial view of  FIG. 1 , can be at least partially in a separate subhousing  60  that is connected by a second connection  63 , for example a screw as exchangeable part to the base  10 . This alternative improves serviceability by making possible a faster exchange of only the exchangeable part. 
     At least one first seal  13  is provided between the piston  40  and the cylinder chamber  12 , a second seal  14  is provided between the piston  40  and the adjusting spindle  30 , and a third seal  15  is provided between the adjusting spindle  30  and the base  10  to prevent leakage of a pressure medium M or a vacuum in the chamber  12 . The pressure medium is usually air, oil or hydraulic fluid. 
     A pressure medium M is introduced through a connection  46  in the base  10  at a first pressure p 1  into the cylinder chamber  12  for applying a first force F 1  against a back face  42  of the piston  40  directed away from the first tool  21 . The piston  40  axially displaceable in the chamber  12  moves through a stroke L when subjected to a first force F 1 , the stroke being limited by an abutment formed by a front end wall  11  of the cylinder chamber  12 . As illustrated, the abutment can be integrally connected to the base  10  or can be formed as an attachment, for example in the form of a plug-in or screw-in sleeve or a retaining ring. This embodiment allows such plug-in or screw-in sleeves with different lengths to be exchangeable parts fittable in the base  10  so the abutment for the piston  40  can be changed for example by rotating the plug-in sleeves in the first bore  17 . The maximum stroke of the piston  40  is limited in that the pistons front face  43  directed toward the tool  21  directly engages the abutment formed by the front wall  11 . 
     A vacuum connection  47  is provided in the front wall of the housing  10  through which a vacuum  48  can be applied to the chamber  12  between the front wall  11  and the front face  43  directed toward the tool so as to pull the piston  40  by a suction force F 4  toward the front wall  11 . 
     The adjusting spindle  30  has a front part  37  extending through a third bore  41  in the piston  40  and axially displaceable relative to the piston  40 . The third bore  41  in the piston  40  is internally threaded and the front part  37  is complementarily externally threaded and screwed into the third bore  41 . Usually, a fine or trapezoidal is provided between the front part  37  and the third bore  41  so as to allow for a precise positioning and a fine adjustment of the adjusting spindle  30 . 
     As shown in  FIG. 1 , a controller  70  sets the first pressure p 1  or the vacuum  48  in the chamber  12  and sets the tractive force F 2  acting on the retraction rod  25  depending on the material and the outer dimensions of a blank  5  to be rolled in the profile rolling machine. Thus, the pressures p 1 , p 2  and p 3  or, the vacuum  48  and the pulling and/or forces F 1 , F 2 , F 3  or, the suction force F 4 , generated therefrom for the piston  40  and the retraction rod  25  are precisely matched to each other. A detailed description of the procedures is illustrated as operational sequence in the  FIGS. 5   a  to  5   e.    
       FIG. 2  shows the apparatus  100  after the profile rolling in a position that is open with respect to the blank  5 . The movable tool  21  is separated by a gap X from the fixed tool or die  22 . In this illustrated adjustment position, the blank  5  can be moved freely between the tool  21  and the die  22 . The first pressure p 1  or the vacuum  48  in the chamber  12  is set to almost zero. The actuator  50  shifts the retraction rod  25  rearward through a stroke corresponding to the gap X, that is in a direction away from the tool  21 . The tool  21  is positioned against the abutment end face  23  of the adjusting spindle  30 . In the cylinder chamber  12 , the piston  40  abuts rearward, that is in a direction away from the tool  21 , against a third abutment  18  formed by the rear end face of the chamber  12 . 
       FIG. 3  shows the apparatus  100  in a side view. A roller or slide  62  between the tool  21  and the base  10  supports and guides the tool  21  and/or its support  20  during axial displacement when positioning the tool  21  against the blank  5 . As illustrated, the roller  62  can be a cylinder or a ball. Alternatively, a flat sliding element  62  in the form of a slide nut is conceivable. 
       FIG. 4  shows an alternative embodiment of the apparatus  100  in an adjustment position (also shown in  FIG. 1 ) closed with respect to the blank  5 . In this embodiment, the piston  40  has an axially forwardly projecting front extension sleeve  44  extending from its front end toward the tool  21  and this sleeve  44  is mounted and guided in the first bore  17  in the front wall of the base  10 . Furthermore, on the back face  42  directed away from the tool  21 , the piston  40  has an axially rearwardly projecting rear extension sleeve  45  that also slides in the first bore  17  in the base  10 . Depending on the design it is advantageous if the projecting sleeves  44  and  45  have different diameters and the first bore  17  is complementarily shaped. In order to prevent the pressure medium M or the vacuum  48  from leaking out of the chamber  12 , respective seals  13 ,  15  are provided between the piston  40  and the chamber  12  and between the second projecting sleeve  45  and the first bore  17 . 
     The apparatus  100  operates as shown by  FIGS. 5   a  to  5   e  as follows: 
       FIG. 5   a  shows the apparatus  100  in a zero position for adjusting the spindle  30 . The actuator  50  applies the pressure p 3  to the retraction rod  25  so it engages with a force F 3  against the tool  21  and presses same forward toward the die  22 . The pressure medium M creates the first pressure p 1  in the chamber  12  against the back face  42  of the piston  40  to apply to it an axially forwardly directed force F 1  and press the piston  40  forward against the abutment formed by the front wall  11 . Alternatively, the piston  40  can also be displaced by a vacuum  48  in the chamber  12  by suction force F 4  against the abutment  11 . The displacement of the piston  40  and the associated synchronous displacement of the adjusting spindle  30  determines the gross stop position or displacement path s for the tool  21 . 
       FIG. 5   b  shows the apparatus in an operating position with a gap X between the tool  21  and the die  22  so there is space for the blank  5  to be formed. In this working position, the first pressure p 1  of the pressure medium M or the vacuum  48  is adjusted by the controller  70  depending on the tractive force F 2  acting on the retraction rod  25  in such a manner that a first force F 1  or, in case of the vacuum  48 , a suction force F 4  applied in the chamber  12  to the piston  40  that is greater than the tractive force F 2  of the retraction rod  25 . This ensures that the piston  40  moves forward into an end position against the front-wall abutment  11  in the housing  10  and the tool  21  engages in an operating position against the stop formed by the end face  23  of the adjusting spindle  30 . 
       FIG. 5   c  is the same as  FIG. 5   b , but, in addition, the blank  5  is shown here pulled for the machining process into the gap X between the tool  21  and the die  22 . 
       FIG. 5   d  shows the position of the apparatus  100  for example in case of a malfunction when the blank is already unevenly deformed between the tool and the die during profile rolling thereby jams the apparatus  100  so further production is no longer ensured. The pressure or force conditions as well as the stop position of the tool  21  and the piston  40  correspond to those described in connection with  FIGS. 5   b  and  5   c.    
       FIG. 5   e  shows the releasing or opening of the apparatus  100 . To do this, the pressure or force conditions acting on the piston  40  and on the retraction rod  25  are changed. The first pressure p 1  of the pressure medium M or the vacuum  48  is reduced to a value close to zero. The tractive force F 2  generated by the actuator  50  acts axially rearward, away from the tool  21  on the retraction rod  25 , with the tool  21  bearing with the tractive force F 2  against the tool stop  23  of the adjusting spindle  30 , and the tool  21  with the retraction rod  25  and the adjusting spindle  30  with the piston  40  move together axially rearward away from the tool  21  until the piston  40  abuts against the third abutment  18  in the chamber  12 . The gap X is now at a maximum so that the blank  5  can be removed. 
     The technical features represented by the reference numbers are equivalent in all figures and are explained in the reference list below. 
     
       
         
           
               
             
               
                   
               
               
                 Reference list 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                   
                   5 
                 Blank 
               
               
                   
                   
                  10 
                 Base 
               
               
                   
                   
                  11 
                 First abutment 
               
               
                   
                   
                  12 
                 Chamber 
               
               
                   
                   
                  13 
                 First seal 
               
               
                   
                   
                  14 
                 Second seal 
               
               
                   
                   
                  15 
                 Third seal 
               
               
                   
                   
                  17 
                 First bore 
               
               
                   
                   
                  18 
                 Third abutment 
               
               
                   
                   
                  20 
                 Tool support 
               
               
                   
                   
                  21 
                 Tool 
               
               
                   
                   
                  22 
                 Die (= counter tool) 
               
               
                   
                   
                  23 
                 Tool stop 
               
               
                   
                   
                  24 
                 Pressure surface 
               
               
                   
                   
                  25 
                 Retraction rod 
               
               
                   
                   
                  26 
                 First connection 
               
               
                   
                   
                  27 
                 Guide groove 
               
               
                   
                   
                  28 
                 Second bore 
               
               
                   
                   
                  30 
                 Adjusting spindle 
               
               
                   
                   
                  37 
                 Front part 
               
               
                   
                   
                  38 
                 Rear part 
               
               
                   
                   
                  40 
                 Piston 
               
               
                   
                   
                  41 
                 Third bore 
               
               
                   
                   
                  42 
                 Back face 
               
               
                   
                   
                  43 
                 Front face 
               
               
                   
                   
                  44 
                 First projecting sleeve 
               
               
                   
                   
                  45 
                 Second projecting sleeve 
               
               
                   
                   
                  46 
                 Pressure connection 
               
               
                   
                   
                  47 
                 Vacuum connection 
               
               
                   
                   
                  48 
                 Vacuum 
               
               
                   
                   
                  50 
                 Actuator 
               
               
                   
                   
                  60 35   
                 Housing 
               
               
                   
                   
                  62 
                 Sliding element 
               
               
                   
                   
                  63 
                 Second connection 
               
               
                   
                   
                  70 
                 Controller 
               
               
                   
                   
                 100 
                 Apparatus 
               
               
                   
                   
                 s  40   
                 Displacement path 
               
               
                   
                   
                 X 
                 Gap 
               
               
                   
                   
                 F1 
                 First force (adjusting spindle) 
               
               
                   
                   
                 F2 
                 Tractive force 
               
               
                   
                   
                 F3 45   
                 Second force (retraction rod) 
               
               
                   
                   
                 F4 
                 Suction force 
               
               
                   
                   
                 p1 
                 First pressure 
               
               
                   
                   
                 p2 
                 Second pressure 
               
               
                   
                   
                 p3 50   
                 Third pressure 
               
               
                   
                   
                 M 
                 Pressure medium