Abstract:
A clamping device for an adjustable stop of a processing machine for guiding workpieces through the processing machine is provided with at least one clamping part that clamps the stop against at least one counter stop. The clamping part is provided on a transmission element, wherein the transmission element is acted upon with a force (F 1 ) that is converted into a clamping force (F 2 ) acting upon the clamping part. A release unit is provided for releasing the clamping action. The transmission element is a two-armed lever, one arm of which is acted upon with the force (F 1 ) in the form of a compressive force and the other arm of which generates the clamping force (F 2 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention pertains to a clamping device for an adjustable stop of a processing machine, particularly a moulding machine, for guiding workpieces through the processing machine, with at least one clamping part by means of which the stop can be clamped against at least one counter stop. 
         [0002]    The invention pertains also to a processing machine, particularly a moulding machine, comprising such a clamping device. 
         [0003]    In processing machines, particularly moulding machines, it is known to guide the workpieces for working along working tools. During this process, the workpieces rest against a stop. This stop must be precisely positioned relative to the cutting circle diameter of the assigned tool in order to ensure that the workpiece is exactly guided through the processing machine. Correctly adjusted stops are one of the decisive factors for the quality of the workpieces being processed. The stop is mechanically clamped in the processing machine by means of screws. The tools must be frequently changed depending on the type of processing to be carried out on the workpiece. Since the tools often have different cutting circle diameters and moulding depths, it is necessary to adjust the stop with respect to the different cutting circle diameters of the tools. In order to carry out such an adjustment, it is necessary to loosen the screws that can only be difficultly accessed from the rear side of the stop and sometimes require a change of the machine adjustment or the removal of other machine components. Due to the difficult access, a potential risk of injuries to the machine operator also cannot be excluded. 
         [0004]    The invention is based on the object of designing the clamping device and the processing machine of the initially cited type in such a way that the stop can be clamped in a constructively simple fashion, wherein the clamping can also be easily and safely released as required. 
       SUMMARY OF THE INVENTION 
       [0005]    According to the invention, this object is solved for a clamping device of the aforementioned kind in that the clamping part is provided on a transmission element, wherein the transmission element is acted upon with a force (F 1 ) that is converted into a clamping force (F 2 ) acting upon the clamping part, and in that a release unit is provided for releasing the clamping action. 
         [0006]    The object is further solved for a processing machine of the aforementioned kind in that it comprises a clamping device as set forth above. 
         [0007]    The inventive clamping has the transmission element, by means of which the clamping part can be actuated. The transmission element is acted upon with a force that is converted by the transmission element in such a way that a clamping force acts upon the clamping part. The clamping force acting upon the clamping part therefore can be generated in a purely mechanical fashion. The clamping is released by means of a release unit. 
         [0008]    The transmission element advantageously is a two-armed lever, one arm of which is subjected to the force in the form of a compressive force and the other arm of which generates the clamping force. In this case, the clamping force is directed opposite to the compressive force. The two-armed lever is a constructively simple component that can generate a high clamping force when it is subjected to a low compressive force due to the lever action. 
         [0009]    In an advantageous embodiment, the force is generated by at least one pressure spring that is arranged on an axis fastened in the counter stop. The pressure spring is a cost-effective component that can be easily installed and also removed as required. The pressure spring particularly is also a safe and reliable component after a prolonged period of use. 
         [0010]    The clamping part is advantageously seated on one end of a ram that penetrates the corresponding arm of the lever and the counter stop. This ram extends transverse to the adjusting direction of the stop. 
         [0011]    The counter stop advantageously is arranged between the stop and the transmission element. 
         [0012]    In order to enable the ram to actuate the clamping part, the axis, on which the pressure spring is arranged, and the ram penetrate the transmission element with a certain clearance. The axis and the ram advantageously extend parallel to one another and therefore perpendicular to the adjusting direction of the stop. The corresponding openings in the transmission element have a larger diameter than the axis and the ram such that the transmission element can be easily adjusted relative to the ram and the axis. 
         [0013]    In a preferred embodiment, the ram is provided with a counter bearing on the end facing away from the clamping part. The ram is supported on the outer side of the transmission element facing away from the counter stop by means of said counter bearing. The counter bearing and the clamping part therefore lie on different sides of the counter stop, against which the stop is clamped after its adjustment. 
         [0014]    Effective clamping is achieved if the clamping part is a sliding block that lies in a T-groove in the stop. Since the T-groove extends in the adjusting direction of the stop, the stop can be easily displaced in the adjusting direction such that it is spaced apart from the cutting circle diameter of the associated tool by the required distance. The adjusting direction of the stop extends parallel to the transport direction, in which the workpieces to be processed are transported through the processing machine. 
         [0015]    In the clamping position, the clamping part advantageously pulls the stop against the counter stop under the influence of the clamping force. 
         [0016]    In an advantageous embodiment, the counter bearing features a conical socket and a taper disc cooperating therewith. In this way, the transmission element can be pivoted relative to the ram when the clamping is released and, vice versa, when the clamping force should be generated. The conical socket and the taper disc form a ball-and-socket joint of sorts, by means of which it is ensured that the ram can always be acted upon and adjusted in the direction of its longitudinal axis despite an inclined position of the transmission element. 
         [0017]    In order to achieve a high clamping force despite the low force acting upon the transmission element, it is advantageously proposed that the distance between the axis carrying the pressure spring and the pivoting axis of the transmission element is greater than the distance between the ram with the clamping part and the pivoting axis. The pivoting axis of the transmission element extends perpendicular to the adjusting direction of the stop and to the transport direction of the workpieces through the processing machine. 
         [0018]    The transmission element is advantageously actuated by the release unit, in particular, when the clamping of the stop should be released. 
         [0019]    In order to ensure that the release unit only has to generate a low force for releasing the clamping, it advantageously engages on the end of the transmission element facing away from the ram. 
         [0020]    A pneumatic cylinder, as well as a hydraulic cylinder, an electric or an electromagnetic drive, may be used as release unit. 
         [0021]    The release unit is advantageously actuated with a switch. It is arranged on the moulding machine in such a way that it can be comfortably actuated by the operator, wherein said switch is advantageously located outside the region of the tools and the transport devices of the processing machine, but spatially allocated to the stop to be adjusted. In this way, the release unit can be easily yet reliably actuated by the operator with the aid of the switch. Operating errors are thereby prevented. 
         [0022]    The inventive processing machine with the clamping device makes it possible to very quickly adjust the stop with respect to the cutting circle diameter and the moulding depth of the corresponding tool. The clamping force is generated by tensioning the mechanical pressure spring whereas the clamping force is relieved by pivoting the transmission element against the force of the pressure spring by means of a release unit. The pressure spring ensures that the stop is continuously clamped in position as long as the release unit has not been actuated. 
         [0023]    The adjustable stop is advantageously assigned to a right tool of the processing machine. In a moulding machine, in particular, this right tool machines the right longitudinal side of a workpiece referred to the transport direction while it passes through the processing machine. The adjustable stop is located behind the right tool referred to the transport direction of the workpieces through the processing machine. 
         [0024]    The invention is not only defined by the subject matter of the individual claims, but also by all information and features disclosed in the drawings and the description. Even if they are not subject matter of the claims, they are claimed as being essential to the invention insofar as they are novel in comparison with the prior art individually or in combination. 
         [0025]    Other features of the invention result from the other claims, the description and the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The invention is described in greater detail below with reference to an exemplary embodiment that is illustrated in the drawings. 
           [0027]      FIG. 1  shows an inventive processing machine in the form of a perspective view. 
           [0028]      FIG. 2  shows a perspective view of an inventive clamping device for a stop of the inventive processing machine. 
           [0029]      FIG. 3  shows an enlarged section through the clamping device according to  FIG. 2 , in which the stop is in the clamped position. 
           [0030]      FIG. 4  shows in a view corresponding to  FIG. 3 , the stop in the released position. 
           [0031]      FIG. 5  shows an enlarged section along the line A-A in  FIG. 3 .  FIG. 6  shows an enlarged section along the line B-B in  FIG. 3 . 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0032]    In the exemplary embodiment, the processing machine advantageously is a moulding machine, by means of which workpieces can be processed on four sides while they pass through the moulding machine. The workpieces to be processed are fed to a machine table  2  of the moulding machine by means of an infeed table  1 . The workpieces are transported through the moulding machine on this machine table by means of transport rollers  3 . The moulding machine has a lower tool  4 , which is rotatable about a horizontal axis and processes the underside of the workpiece while it passes through the moulding machine. A right tool  6  is arranged in the moulding machine behind the tool  4  referred to the transport direction  5 , wherein this right tool is rotatable about a vertical axis and processes the right longitudinal side of the workpiece referred to the transport direction  5  while it passes through the moulding machine. The other longitudinal side of the workpiece is processed by a left tool  7  that is rotatable about a vertical axis. The two vertical tools  6 ,  7  are arranged offset to one another referred to the transport direction  5  of the workpiece. An upper tool  8 , which is rotatable about a horizontal axis and processes the upper side of the workpiece while it passes through the moulding machine, is located behind the left tool  7  referred to the transport direction  5 . 
         [0033]    The moulding machine is furthermore provided with a lower tool  9  that is arranged behind the upper tool  8  referred to the transport direction  5 , wherein this lower tool is also rotatable about a horizontal axis and once again processes the underside of the workpiece. The moulding machine may have additional right, left, upper or lower spindles depending on the respective application. The workpiece rests against stops  10  with its right longitudinal side referred to the transport direction  5  while it passes through the moulding machine. 
         [0034]    These stops consist of a rigidly arranged stop  11  that lies opposite of the left tool  7  and a stop  12  that is located behind the right tool  6  referred to the transport direction  5  and can be adjusted relative to the circle diameter of this right tool  6  in the transport direction  5  as required. 
         [0035]    The transport rollers  3  are connected to swing holders  14 , which are fastened on a transport beam  15 , by means of feed rockers  13 . The transport beam extends in the transport direction  5  in the region above the machine table  2 . When workpieces should be transported through the moulding machine, the transport rollers  3  are pressed against the workpieces with the aid of pressure cylinders  16  that are supported on the swing holders  14  and engage on the feed rockers  13 . 
         [0036]    The position of the stop  12  depends on the cutting circle diameter and the moulding depth of the right tool  6 . When a tool with a different cutting circle diameter is inserted or when the distance between the stop  12  and the cutting circle diameter changes as a result of the position of the tool  6  transverse to the transport direction  5  of the workpiece and to the stop  12  due to profiling with a corresponding moulding depth, the stop  12  has to be readjusted relative to this tool in the transport direction  3 . During a straight planing operation, the circle diameter is directly aligned with the stop after the right spindle  6 . The adjustment of the stop  12  is limited to a relatively short distance when the cutting circle diameter of the tool changes. When the workpiece is profiled on the right side, which is partially realized with the first right spindle  6  or the so-called jointing spindle, but primarily with the  2 . right spindle, the moulding depth of the cutting edges protrudes over the stop  12 . In this case, the position of the stop  12  not only depends on the cutting circle diameter of the tool, but also on the dimension, by which the cutting edges protrude and which corresponds to the moulding depth (profiling depth). An adjustment of the stop  12  is therefore required, in particular, when changing from a straight planing operation to a profiling operation. The adjusting direction of the stop  12  extending parallel to the transport direction  5  is indicated by the double arrow  17  in  FIG. 2 . In the working position, the stop  12  is clamped in position such that it cannot be inadvertently adjusted relative to the tool  6 . This is realized with a clamping device  18  that is described in greater detail below with reference to the following figures. 
         [0037]      FIG. 2  shows two table panels  19 ,  20  that are respectively assigned to the right tool  6  and the left tool  7  ( FIG. 1 ) and can be adjusted relative to the corresponding tool  6 ,  7  perpendicular to the transport direction  5 . A guide rail  21  is arranged rigidly referred to the machine between the two table panels  19 ,  20 , wherein the table panels  19 ,  20  are guided on said guide rail with their longitudinal sides that face one another. The guide rail  21  is advantageously screwed on the (not-shown) machine stand. 
         [0038]    On its opposite longitudinal side, the table panel  20  is during the adjustment guided transverse to the transport direction  5  on another guide rail  22  that is arranged rigidly referred to the machine. A guide rail or another table panel is also arranged in front of the table panel  19  referred to the transport direction  5 . 
         [0039]    The adjustable stop  12  is clamped in the working position ( FIG. 3 ) by means of the clamping device  18 . It has a lever  23  that can be respectively pivoted or tilted about a vertical axis  24 . The axis  24  is advantageously formed by a cylindrical pin that is arranged between the lever  23  and a stop carrier  25 . It is advantageously placed into a respective downwardly and upwardly confined groove in the lever  23  and in the stop carrier  25  such that it cannot fall out after the installation. The stops  11 ,  12  are flatly placed against the stop carrier  25  with their rear sides  26 ,  27  that face away from the left tool  7 . The stops  11 ,  12  respectively extend perpendicular to the machine table  2  and the table panels  19 ,  20 . The stop carrier  25  has an approximately square cross section and is advantageously lower than the stops  11 ,  12 . 
         [0040]    The axis  24  is located in the region of the adjustable stop  12  near its end. In this end region, the lever  23  is penetrated by a stud bolt  28  with a certain clearance. This clearance is dimensioned so large that the lever  23  can be pivoted relative to the stop carrier  25  ( FIG. 4 ). The stud bolt  28  also penetrates the stop carrier  25 , which is provided with a corresponding through-opening  30  for this purpose. Its diameter is slightly larger than the diameter of the stud bolt  28  such that the stud bolt  28  easily can be axially displaced therein. It protrudes into a T-groove  31  ( FIGS. 3 and 6 ) provided in the rear side  27  of the displaceable stop  12 . The T-groove extends from the side resting against the stop  11  close to the opposite end face  32  of the stop  12 . A sliding block  33 , which is held in the T-groove and can be displaced relative to the stop  12  in the adjusting direction  17 , is seated on the end of the stud bolt  28  that protrudes into the T-groove. 
         [0041]    A conical socket  34  is seated on the other end of the stud bolt  28  that protrudes over the lever  23 , wherein a taper disc  35  engages into said conical socket ( FIG. 5 ). It is held in contact with the conical socket  34  by means of a nut  36  that is screwed on the free end of the stud bolt  28  and preferably realized in a self-locking fashion. Due to this arrangement, surface contact is always ensured regardless of the pivoting or tilting motion of the lever  23 . The conical socket  23  also has a sufficiently large diameter referred to the stud bolt  23  such that the conical socket  34  and the stud bolt  23  do not get stuck on one another during the pivoting motion of the lever  23  and the conical socket  34  resting against said lever. 
         [0042]    The stop carrier  25  is respectively screwed and pinned on the guide rail  21  and the machine stand by means of screws  37  and pins  38  ( FIG. 3 ). The fixed stop  11  is fastened on the stop carrier  25  by means of screws  39 ,  40 . The screws  39 ,  40  are screwed into the rear side  26  of the fixed stop  11 . The screw heads are advantageously countersunk in the rear side  41  of the stop carrier  25  that faces away from the stop  11 . The stop  11  can be reliably fastened on the stop carrier  25 , against which it flatly rests, with the aid of the screws  39 ,  40 . At the height of the screws  39 ,  40 , the lever  23  is provided with through-openings  42 ,  43 , into which a tool for actuating the screws  39 ,  40  can be inserted. 
         [0043]    A threaded rod  44  is screwed into the rear side  41  of the stop carrier  25  and protrudes over the rear side  45  of the lever  23  that faces away from the stop carrier  25 . The opening  46  in the lever  23 , through which the threaded rod  44  protrudes, has a larger diameter than the threaded rod  44 . In this way, the lever  23  can be respectively tilted or pivoted about the axis  24  as described in greater detail further below. The section of the threaded rod  44  protruding over the lever  23  is surrounded by a pressure spring  47  ( FIG. 5 ), one end of which is supported on the rear side  45  of the lever  23  by means of a disc  48 . The other end of the pressure spring  37  rests against a disc  49  that surrounds the threaded rod  44  and is supported on a nut  50  screwed on the free end of the threaded rod  44 . The nut  50  is preferably realized in a self-locking fashion. The nut  50  serves for adjusting the pretension of the pressure spring  47 . In the clamping position illustrated in  FIG. 3 , the pressure spring  47  exerts the force F 1  upon the lever  23  ( FIG. 3 ). 
         [0044]    According to  FIG. 3 , the threaded rod  44  and the stud bolt  28  lie on opposite sides of the axis  24 . The axis of the threaded rod  44  is spaced apart from the axis  24  by the distance I, and the axis of the stud bolt  28  is spaced apart from said axis by the distance I 2 . In this case, the distance is greater than the distance I 2 . 
         [0045]    In the clamping position illustrated in  FIG. 3 , the lever  23  exerts the force F 2  upon the stud bolt  28  by means of the conical socket  34 , the taper disc  35  and the nut  36 . It is directed opposite to the force F 1  because the stud bolt  28  and the threaded rod  44  with the pressure spring  47  are arranged on opposite sides of the axis  24 . 
         [0046]    A release unit  51  has a piston rod  52  that engages with its free end into a recess  53  provided in the rear side  41  of the stop carrier  25 . It is arranged near the end of the stop carrier  25  that lies opposite of the stud bolt  28 , as well as the threaded rod  44 . The piston rod  52  forms part of a pneumatic cylinder  54  that is rigidly connected to the lever  23 . The pneumatic cylinder  54  is preferably screwed into a threaded bore  55  of the lever  23 . A pneumatic line  56  is connected to the pneumatic cylinder  54 . According to  FIG. 2 , the pneumatic line  56  connects the pneumatic cylinder  54  to a pneumatic valve  57  that can be actuated with a switch  58 . The switch  58  is arranged on the moulding machine in such a way that it can be comfortably actuated by the operator. On the piston side that lies opposite of the connection to the pneumatic line  56 , the pneumatic cylinder  54  is provided with an outlet  59 , through which air can respectively escape from the piston rod side during the extension of the pneumatic cylinder  58  and flow in during the retraction thereof. The outlet  59  is advantageously provided with a sound absorber. 
         [0047]    The pneumatic cylinder used may also consist of a pneumatic cylinder that can be loaded in both directions. 
         [0048]    In the clamping position according to  FIG. 3 , the pneumatic cylinder  54  is retracted such that the piston rod  52  only protrudes slightly over the pneumatic cylinder  54 . In the illustration according to  FIG. 3 , the force of the pressure spring  47  acts upon the lever  23  counterclockwise in the direction of the stop carrier  25 . The piston rod  52  rests against the bottom  60  of the recess  53 . Since the stud bolt  28  is located on the side of the axis  24  facing away from the threaded rod  44 , the stud bolt  28  is respectively pushed or acted upon outward by the lever  23 . As a result, the sliding block  33  is firmly pressed against the wall  61  ( FIG. 6 ) of the T-groove  31  that faces the stop carrier  25 . In this way, the stop  12  is pressed against the front side  62  of the stop carrier  25  with great force and therefore locked. 
         [0049]    The stop  12  therefore is exclusively clamped in position with the force of the pressure spring  47 . In the clamping position, the correlation F 1 ×I 1 =F 2 ×I 2  applies. This results in F 2 =F 1 ×I 1 /I 2 . With consideration of the fact that the distance I 1  is greater than the distance I 2 , the resulting force F 2 , with which the stud bolt  28  pulls the sliding block  33  against the wall  61  of the T-groove  31 , is greater than the force F 1  exerted upon the lever  23  by the pressure spring  47 . 
         [0050]    The force F 2  can be adjusted correspondingly high by choosing the distance ratio accordingly. 
         [0051]    The force F z  ( FIG. 4 ) exerted by the pneumatic cylinder  54  is relatively low. The correlation F Z ×I Z =F 1 ×I 1  results in F Z =F 1 ×I 1 /I Z . Since the lever arm l z  (corresponding to the distance between the axis  24  and the axis of the piston rod  52 ) is significantly longer than the lever arm the resulting force F Z  is significantly lower than the force F 1 . As mentioned above, the force F 1  exerted upon the lever  23  by the pressure spring  47  is significantly lower than the clamping force F 2  exerted by the stud bolt  28  such that the clamping with the required high clamping force can be released with a relatively low release force. 
         [0052]    If the stop  12  should be adjusted in the adjusting direction  17 , the pneumatic cylinder  54  is extended ( FIG. 4 ) by actuating the switch  58 . The piston rod  52  always rests on the bottom  60  of the recess  53  of the stop carrier  25 . This is ensured by the pressure spring  47  that continuously acts upon the lever  23  in the counterclockwise pivoting direction. Since the pneumatic cylinder  54  is rigidly connected to the lever  23 , the lever  23  is now pivoted about the axis  24  in the clockwise direction. The stud bolt  28  therefore is relieved of the force F 2  and can be displaced in the direction of the bottom  63  of the T-groove  31  together with the sliding block  33 . The clamping of the stop  12  is thereby released such that the required clearance between the stop  12  and the stop carrier  25 , as well as between the sliding block  33  and the T-groove  31 , is adjusted and the stop  12  can now be displaced into the new position relative to the stop carrier  25  in the adjusting direction  17 . Once the desired position of the stop  12  is reached, the valve  57  is changed over by means of the switch  58  such that the pneumatic cylinder  54  once again moves back into the initial position illustrated in  FIG. 3 . This is achieved in that the lever  23  is pivoted back under the influence of the pressure spring  47  such that the piston rod  52  of the pneumatic cylinder  54  is retracted. During this process, the pneumatic medium in the pneumatic cylinder  54  can escape through the pneumatic line  56  and the valve  57 . The sliding block  33  is once again pulled against the wall  61  of the T-groove  31  with great force by the stud bolt  28  that is supported on the lever  23  in the above-described fashion. The stop  12  is then firmly clamped on the stop carrier  25 . 
         [0053]    The stop  12  is mechanically clamped in the described fashion in that a lever transmission converts the force F 2  exerted by the pressure spring  47  into a high clamping force acting upon the adjustable stop  12 . The release unit  51  with the pneumatic cylinder  54  merely serves for releasing the clamping by pivoting the lever  23  against the force of the pressure spring  47 . As a result, the stud bolt  28  is now displaced into the release position together with the sliding block  33  such that the clamping of the stop  12  is released. The stop  12  can now be adjusted into the desired position relative to the tool  6  in the transport direction  5  or in the adjusting direction  17 , respectively. In order to allow an exact adjustment, a scale  64  is provided on the stop carrier  25 , wherein an end face  65  of the stop  12  that faces the fixed stop  11  is assigned to said scale. 
         [0054]    The operator can easily release the clamping of the stop  12  by means of the switch  58 . The pressure spring  47  ensures a reliable pretension of the stop  12 . A high operating comfort is achieved because the operator merely has to actuate the switch  58 . Operating errors, in particular, are thereby prevented. No additional tools are required for releasing the stop  12  at locations that are difficult to access, wherein said tools are also frequently misplaced and therefore not readily available in practical applications. Since the stop  12  can be easily adapted to the cutting circle diameter of the tool  6 , high processing quality of the workpieces is simultaneously ensured. 
         [0055]    Instead of using a pneumatic drive, the clamping can also be released with any other suitable drives such as a hydraulic drive, an electric or an electromagnetic drive. 
         [0056]    In the described exemplary embodiment, the lever  23  is a two-armed lever. This is the reason why the compressive force F 1  and the clamping force F 2  are directed opposite to one another. However, the lever  23  may also be realized in the form of a one-armed lever. In this case, the axis  24  lies on the side of the stud bolt  28  facing away from the threaded rod  44 . The distances and I 2  also differ in this case, wherein the distance is once again greater than the distance I 2 . The force F 1  and the clamping force F 2  act in the same direction in such a lever design. In such a design, the clamping force F 2  would be exerted when the lever  23  is pivoted in the clockwise direction, i.e. the force F 1  must act opposite to the direction in the above-described exemplary embodiment. In this case, the release unit  51  must pivot the lever  23  in the counterclockwise direction in order to release the clamping. 
         [0057]    The force F 1  may be respectively exerted upon the lever  23  in the form of a compressive force, as well as in the form of a tensile force. 
         [0058]    The specification incorporates by reference the entire disclosure of German priority document 10 2014 016 631.7 having a filing date of Nov. 4, 2014. 
         [0059]    While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.