Abstract:
A work bench has a pair of clamping jaws supported on parallel spaced apart beams. At least one of the jaws moves toward the other by means of driving members that are associated with each beam. Each of the driving members for the at least one movable jaw is capable of being individually actuated. The driving members include a step-by-step or ratchet drive constructed and arranged so that each of the drive members can be individually actuated or actuated in unison with one foot of a user via a double-lever construction. The workbench enables hands-free actuating and clamping of both symmetric or prismatic and asymmetric or non-prismatic parts and components.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a workbench having clamping jaws which rest on two parallel beams and of which at least one can be displaced in the direction of the other clamping jaw by means of drive members which are associated with each beam and can be operated individually. 
     Workbenches of this type are known in various design forms. Thus, for example, in DE-C2 44 18 687 and DE-C2-44 18 688, a fold-up workbench having two clamping jaws is described. One clamping jaw can be moved along the beams by means of two spindle drives which can be operated by a hand crank. 
     The content of these German patent references is hereby incorporated by reference herein. 
     One problem is known for these types of workbenches. It is difficult to provide a hands-free operation workbench that also would be capable of clamping non-prismatic workpieces. 
     SUMMARY OF THE INVENTION 
     This problem is first solved by providing a workbench constructed in accordance with the present invention. In that regard, one object of the present invention is to provide a workbench that permits hands-free operation and yet ensures the capability of clamping non-prismatic workpieces. In one embodiment, a workbench of the present invention has at least a pair of clamping jaws that rest on two parallel beams wherein one of the clamping jaws can be displaced in the direction of the other clamping jaw by drive members associated with each beam. The drive members can be operated individually or simultaneously. The drive members each have a drive which can be operated step by step and can be operated together or individually with one foot of an operator by a double lever technique. As a result of this configuration, the clamping of workpieces can be carried out in the simplest manner with the hands of an operator free. The workpiece can therefore be held by the operator in the position in which it is to be clamped. The displaceable clamping jaw is moved in the direction of the other clamping jaw by means of a foot operation. By the arrangement of a foot-operable double lever construction the drive members of each beam for the displaceable clamping jaw can be operated individually, which also makes it possible to clamp nonprismatic workpieces. For this purpose, the double lever is formed such that each individual lever can be operated in order to operate a drive member for the clamping jaw, and both drive members can also be operated at the same time, for uniform parallel displacement of the clamping jaws. 
     In one embodiment, the drive has a pulling or pushing rod that is secured to the clamping jaw and that can be displaced step by step or incrementally by a latching or clamping portion that in turn can be displaced by a pedal. A clamping or latching drive for the displaceable clamping jaw is thus provided, such as is known, for example, from cartridge pressure-emptying devices. By means of foot-operation of one or both foot levers of the double lever, the pulling or pushing rod is displaced step by step by latching or clamping portions in the direction of the clamping position of the workpiece. 
     In one embodiment, the clamping or latching drive further includes a releasable reverse-pressure lock. The latter can also be formed as a latching or clamping portion. In order to release the clamping position again, this reverse-pressure lock can be released, after which the clamping jaw can be displaced back again in the direction of the original position. 
     In one embodiment, the reverse-pressure lock is releasable by a reverse pedal operation. Provision is therefore made, for example, for a forward displacement of the clamping jaw into the clamping position to be achieved by pressing down the pedal or both pedals, and for release of the reverse-pressure lock to be achieved by lifting the pedal. Thus, both the clamping and the releasing of the workpiece after it has been worked on can be carried out with the hands free. 
     In one embodiment, the latching or clamping portion is further displaceable by an operating lever. In one embodiment, the operating lever is coupled to the pedal by a drive rod. In this case, preference is given to an arrangement in which an operating lever which is connected to a pedal by way of a drive rod is associated with each drive of the clamping jaw. In order to displace the pulling or pushing rod, the respective operating lever can be connected, for example in a pivotable manner, to the latching or clamping portion. However, it is also conceivable to act on the latching or clamping portion merely by means of the operating lever and, in this way, to achieve a displacement. 
     In one embodiment, the operating lever enters into a driver opening in a locking portion to release the reverse-pressure lock. By means of an appropriate displacement of the operating lever—as already mentioned, preferably by means of a reverse pedal operation—the locking piece is dragged along by way of the driver opening in such a way that this locking portion is pivoted or displaced into a position which releases the pulling or pushing rod. After this, the clamped workpiece is released. Furthermore, when the reverse-pressure lock is released, the clamping jaw can be displaced back again. 
     In one embodiment, the double pedal is disposed approximately at the center of a cross-member of the workbench. It proves to be particularly advantageous in terms of operation for the double pedal to be shaped like a gateway. By pressing down one or both pedals by means of foot operation, the clamping jaw is displaced forwards, as described. In order to release the reverse-pressure lock as a result of a reverse pedal operation, the foot passes through the double-pedal gateway and acts on the underside of the pedals by pulling the pedals. In one embodiment the drive rod and be pivoted in each case on a pivoting lever, the lever being mounted on a shaft which can be rotated by the foot pedal. The lever is disposed in the region of a supporting leg and extends in the U-shaped space in the supporting leg, which is shaped as a U-section. The drive rods coupled to the operating levers of the respective drives are thus located in a hidden position within the U-shaped spaces in the supporting legs. In one embodiment the clamping or latching drive is disposed approximately at the centre of the beam, underneath a bottom sliding bearing formed by a U-shaped beam section. 
     In one embodiment, the other clamping jaw can be mounted on the beams so that it can be moved by a spindle. This provides greater variability in the clamping area. In this case, this clamping jaw can be moved in a known manner along the beams in the direction of the one clamping jaw by means of two spindle drives which can be operated by a hand crank. In this case, it proves to be particularly advantageous for a beam section carrying the other clamping jaw to be capable of being pivoted up into a 90° position. This 90° position of the other clamping jaw can preferably be achieved only when the one clamping jaw is displaced completely back. In one embodiment, the other clamping jaw, when in the pivoted-up position, can be engaged against the broad face of the foot-operated clamping jaw. It is therefore possible for workpieces to be clamped vertically as well, for example in order to work on the sides thereof. In this case, clamping is carried out by means of the above-described spindle displacement of the pivoted-up clamping jaw. 
     The inventive features described are preferably provided on a fold-up workbench, such as is used in particular in the do-it-yourself sector. In this respect, it is proposed to make it possible for the supporting legs of the workbench to be folded into a position parallel to the beams and, in the position of use, to be locked to the beams. However, suitable configurations on professional workbenches are also conceivable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is explained in more detail below with reference to the accompanying drawings, which illustrate only an exemplary embodiment and in which: 
     FIG. 1 shows a plan view of a workbench according to the invention; 
     FIG. 2 shows a view according to the arrow II in FIG. 1; 
     FIG. 3 shows the section along the line III—III in FIG. 1; 
     FIG. 4 shows the section along the line IV—IV in FIG. 3; 
     FIG. 5 shows perspective detailed illustration showing the area of a double pedal for operation of drive members of a clamping jaw; 
     FIG. 6 shows enlarged detail of the region VI—VI in FIG. 3, relating to a rest position of the illustrated drive; 
     FIG. 7 shows an illustration corresponding to FIG. 6, but during the operation of the drive to displace the one clamping jaw forward; 
     FIG. 8 shows a further illustration corresponding to FIG. 6, but at the time the drive is released for return displacement of the one clamping jaw; 
     FIG. 9 shows an alternative configuration of the drive housing in a sectional illustration; and 
     FIG. 10 shows a side view according to FIG. 2, but in a pivoted up 90° position of the other clamping jaw. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Illustrated and described first with reference to FIGS. 1 and 2, is a workbench  1  formed as a clamping bench and having two clamping jaws  3 ,  4  resting on two parallel beams  2 . 
     The left-hand clamping jaw  4  illustrated in FIGS. 1 and 2 can be moved along the beams  2  in a known manner by two spindle drives which can be operated by means of hand cranks  5 . 
     At their ends opposite the hand cranks  5 , the two beams  2  are connected to each other by a transverse beam  6 . In addition, the two beams  2  have a U-shaped cross section which is downwardly open, the web of the U-shaped sections forming a sliding bearing surface  70 . 
     The longitudinal extent of the two beams  2  is subdivided into a stationary beam section  7  and a beam section  8 . In a basic position according to FIGS. 1 and 2, the beam section  8  forms an extension of this stationary beam section  7  and is pivotably secured to the stationary section. The beam section  8  carries the spindle-driven clamping jaw  4 . The two beam sections  7  and  8  are formed to be of approximately the same length. 
     In order to form a stationary top frame, in each case on the outside of each stationary beam section  7 , there are attached sheet-metal cheeks  9  extending over the entire length of the beams  2 . At the top, these sheet-metal cheeks terminate flush with the surface of each web of the stationary U-shaped beam sections  7  and, in their region projecting beyond the stationary beam section  7 , form a support for the webs of the pivotable U-shaped beam sections  8  in their horizontal alignment. 
     Two supporting legs  10  and  11  are mounted on each of the sheet-metal cheeks  9 . The supporting legs  10  and  11  can be pivoted in order to fold up the workbench  1 . The pivotal mounting of the supporting legs is provided in identical manner on both sides of the bench. At its upper end, the leg  11  is mounted such that it can be pivoted about a pivot pin  12 , which is supported in the respective sheet-metal cheek  9 . The leg  10  is by contrast mounted at a lower pivot point such that it can be pivoted about a pivot pin  13 . 
     The supporting legs  10 ,  11  each have a U-shaped cross-section and are arranged with the open side of the U-shaped cross-section facing each other. The pivot pins  12 ,  13  each pass through side walls of the supporting legs  10 ,  11 , the pivot pin  12  being accommodated by a matched, round bearing hole  14 , while the pivot pin  13  is accommodated by an elongated hole  15 , whose longitudinal axis extends in the longitudinal direction of the supporting leg  10 . 
     The supporting leg  10  has an extension  16 , at the upper end of which there is formed a notch or latching hollow  18  provided with a detent step  17 . When the bench is fully set up or unfolded according to FIGS. 1 and 2, a latching pin  19  is latched or received into the latching hollow  18 , the said pin likewise being supported fixedly in the respective sheet-metal cheek  9 . 
     Each pairing of the supporting legs  10  and  11  on each side of the workbench  1  are interconnected to each other by a coupling rod  20 . The coupling  20 , the beam assembly  2 , and the supporting legs  10  and  11  on each side of the workbench  1  constitute a four-bar linkage. However, the linkage includes an additional degree of freedom because the hole  15  for each pivot pin  13  is an elongate hole. 
     In order to fold up the workbench  1  from the position according to FIGS. 1 and 2, clamping levers  21  mounted on the pivot pins  13  are released first. By this, locking is released, after which the upper frame can be lifted at its end on the left in FIG.  2 . In the process, the latching pin  19  is lifted out of the latching hollow  18  on the bench leg. 
     In its free end region, which carries the clamping jaw  4 , the pivotable beam section is formed to be U-shaped in cross section, with a longitudinal slot  22  extending in the web in the longitudinal extent of the U-shaped beam section  8 . Through this there passes a drive member  23  which has a threaded hole in the region of the beam section  8 , that is to say within the U-section, to permit passage of a spindle  24  which can be operated by means of the hand crank  5 . On the upper side of the beam section  8 , the clamping jaw  4  is secured to this drive member  23 . 
     The two side walls  25  of the pivotable U-shaped beam section  8  are extended in order to form frame cheeks. The sidewalls  25  extend on the inside along the stationary beam section  7  and on the outside along the sheet-metal cheek  9 . At their free ends, a pivot pin  26  mounted in the stationary beam section  7  passes through these sidewalls  25 . 
     A curved slot  27  is formed in an enlarged portion depending from the end region of one of the sidewalls  25  of each of the U-shaped beam sections  8 . A stop pin  28  is received through each of the curved slots  27  that is mounted in each stationary beam section  7 . A clamping knob  29  is disposed on the outside of this stop pin  28 . As a result of this configuration, that beam section  8  which carries the clamping jaw  4  can be pivoted up into a 90° position about the pivot pin  26  and can subsequently be secured by the clamping knob  29 . After that, the clamping jaw  4  can be engaged against the broad face  30  of the clamping jaw  3  by way of the spindle drive (see FIG.  10 ). 
     In the region of web of the U-shaped, the stationary beam section  7  carrying the clamping jaw  3  also has a longitudinal slot  31 , through which there passes a drive member  32  carrying the clamping jaw  3 . Within the beam section  7 , that is to say in the region of the U-section, the drive member  32  is fixedly connected to a pulling rod  33  extending in the direction of displacement of the clamping jaw  3 . 
     At the end, this pulling rod  33  enters a drive box  34  disposed approximately at the centre of the beam  2  or in the end region of the stationary beam section  7 . By means of screws  71 , the drive box  34  is secured to the sidewalls of the stationary U-shaped beam section  7 . 
     Accommodated in the drive box  34  is a latching drive  35 . The latter is substantially composed of a latching portion  36  interacting with the pulling rod  33  and a locking portion  72  forming a reverse-pressure lock  37 . The pulling rod  33 , which is provided with a plurality of teeth, passes both through the latching portion  36  and through the locking portion  72 . The locking portion  72  is mounted by corresponding web arrangements such that it can be tilted in the drive box  34 . The underside of the locking portion  72  emerges from the drive box  34  with a free end bent over in an L shape, the free end having formed therethrough a driver opening  38 . 
     By means of a compression spring  39  which surrounds the pulling rod  33 , the latching portion  36  is supported, counter to the direction of displacement of the clamping jaw  3 , against a supporting web  40  of the box. 
     By means of a further compression spring  41 , which is supported by a spring element  42 , the locking portion  72  is biased into a slightly angled position which locks the pulling rod  33  against any reverse movement by engaging the teeth. 
     Also disposed in the drive box  34  is an operating lever  44  which is mounted on and can pivot about a pin  43 . At one end  49 , this operating lever  44  emerges from the drive box  34 , passing through a window-like aperture  45 . The other end, facing into the drive box  34 , is shaped like a hammer head and has, a driving tip  46  which points downwards entering into the driver opening  38  in the locking portion  72 . An arm  47  of the operating lever  44  which is directed upward and extends away from this tip  46  has a rounded, preferably pin-like operating projection  48  at its end. This projection bears against the spring element  42  already mentioned, in order to achieve a basic position. 
     The end  49  of the operating lever  44  which projects freely outwards is connected, by a pivot pin  50 , to a drive rod  51  extending in the U-section of the supporting leg  10 . 
     As is to be seen in particular from FIG. 2, each drive rod  51  of each latching drive  35  extends within the associated supporting leg  10 , starting from the respective operating lever  44 , into a region close to a cross member  52  connecting the two supporting legs  10  to each other. The cross member  52  is likewise formed having a U-shaped cross-section and, in its U-shaped interior, accommodates a rotatable shaft  53  which is divided in two sections over its length. 
     A pivoting lever  54  is mounted to each section of the shaft  53  in the region of the supporting legs  10 . Each pivoting lever  54  projects outward from the U-shaped interior of the cross-member  52  in the direction of the supporting legs  11 . Each pivoting lever  54  carries a pivot pin  55  for pivotal connection of the free, slightly bent-out end of the respective drive rod  51 . 
     At the centre of the cross member  52 , a double pedal  56  is disposed on the shaft  53 , each individual pedal  57  being non-rotatably connected to the respective associated pivoting lever  54  by means of a section of the shaft  53 , and it being possible for the two pedals  57  to be operated independently of each other. The result of this is that a pivoting displacement of one pedal  57  has the effect of a simultaneous pivoting displacement of the pivoting lever  54 . The double pedal  56  is shaped substantially like a gateway, each individual pedal  57  being L-shaped in plan view and their L-shaped webs pointing towards each other. The gateway formed in this way is provided with the reference numeral  58 . 
     By means of the configuration described, the drive members  32  of the clamping jaw  3  can be operated together or individually by one foot, step by step such as for example like a ratchet. For this purpose, one pedal  57  or both pedals  57  are pressed down simultaneously by foot operation. This results in a rotational displacement of the pivoting lever  54  according to the arrow a in FIG.  2 . The displacement of the latching portion  36  by the operating lever  44  which results from this is illustrated in FIG.  7 . As a result of the latching portion  36  being acted on substantially at the end by the operating projection  48  of the operating lever  44 , the latching portion  36  is first canted in such a way that the peripheral edge  59  of the hole  60  passing through the pulling rod  33  engages the teeth on the pulling rod  33 . A further pivoting displacement of the operating lever  44  as a result of the pedal  57  being pressed down then results in an axial displacement of the latching portion  36 , together with the pulling rod  33 . At the same time, the clamping jaw  3  is dragged along by the drive member  32  in the direction of the clamping position. If the pedal  57  is released, then the latching portion  36  returns again into the original position according to FIG. 6, because of the spring force of the compression spring  39 . At the same time, the latching portion  36  drags the operating lever  44  with it and therefore causes the associated reverse rotational displacement of the operating lever  44 . The reverse-pressure lock  37  in this case prevents any reverse displacement of the pulling rod  33 , since here the peripheral edge  61  of the hole  62  through which the pulling rod  33  passes engages the teeth on the pulling rod  33  in order to secure it. As a result of repeated pressing on the pedal  57 , the pulling rod  33 , and therefore the drive member  32  of the clamping jaw  3 , is displaced further and further, step by step, in the direction of the desired clamping position. 
     In addition, the drive shown can also be formed by a clamping portion acting on a pushing rod. 
     As a result of the double pedal arrangement, it is also possible for nonprismatic workpieces to be clamped, in this case the clamping jaw  3  being displaced along the one or the other beam  2 , more or less in the direction of the clamping jaw  4 , by operation of the one or the other pedal  57 . Furthermore, the dual pedal arrangement also permits a uniform, parallel displacement of the clamping jaw  3  to be carried out, this being done by means of operating the pedals  57  together. 
     If the clamping jaw  3  is displaced forwards only on one side, that is to say along only one beam  2 , by means of a pedal  57  in order to clamp a small workpiece, then a clamping force on the workpiece is aided by the reverse-pressure lock  37  of the clamping jaw  3  in the region of the other beam  2 . Accordingly, the clamping jaw  3  cannot yield in the reverse direction in the region of the other beam  2 . On the other hand, slight concomitant dragging in the clamping direction is further provided, the pulling rod  33  travelling over the associated latching portion  36  in the manner of a ratchet. 
     In order to displace the clamping jaw  3  back again, the reverse-pressure lock  37  has to be released. For this purpose, the double pedal  56  or each individual pedal  57  is operated in reverse, that is to say is pulled. This is achieved in the simplest way by the foot passing through the gateway  58  and acting on each individual pedal  57  or both pedals  57  at the same time from below, which results in a rotational displacement of the pivoting lever  54  in accordance with the arrow b in FIG.  2 . As FIG. 8 illustrates, this leads to a pivoting displacement of the locking portion  72  by its being driven by the driving tip  46  of the operating lever  44 . The peripheral edge  61  of the hole  62  is here displaced out of engagement with the teeth of the pulling rod  33 , and thus releases the latter for return displacement of the clamping jaw  3 . 
     The reverse rotational displacement of the operating lever  44  in order to release the reverse-pressure lever  37  is limited by a stop  63  in the region of the aperture  45  in the drive box  34 . 
     An alternative configuration of the drive box  34  is illustrated in FIG.  9 . Here, in order to orient the position of the elements to be inserted—latching portion  36 , locking portion  72  and spring element  42 —pins  64  extending transversely are provided instead of integrally moulded webs. 
     The construction according to the invention ensures hands-free operation during the clamping of workpieces, including the clamping of prismatic workpieces. By simultaneous operation of the double pedal  56 , the clamping jaw  3  is displaced uniformly along the two beams  2 . Single-sided displacement of the clamping jaw  3  along a beam  2  can be carried out by operating only one pedal  57 . 
     Changes and modifications can be made to the invention disclosed in the preferred embodiments and yet fall within the scope of the present invention. The invention is therefore to be limited only by the scope of the appended claims.