Patent Publication Number: US-6655673-B2

Title: Power clamp mechanism

Description:
This is a continuation of Provisional Application Ser. No. 60/240,738 filed Oct. 16, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention broadly relates to a new power clamp mechanism which has unique features and which can be manufactured economically and at low cost. More particularly, this invention relates to a new power clamp mechanism which is made from a single extrusion body. 
     In the past, power clamping mechanisms have been relatively expensive to manufacture and also have generally required the usage of two separate body components; namely, one body component which houses a piston and piston rod assembly for driving the clamp and a second body component used to house a linkage mechanism which is connected to a clamp arm for opening and closing the clamp arm into a clamped locked position or open position. 
     Accordingly, it is a primary object of this invention to provide a unique new power clamp mechanism which can be produced at a relatively low cost and which is formed through the use of a single body member. 
     Another object of the invention is to provide a new power clamp mechanism which is made utilizing a single extruded body for the clamp mechanism and which provides its power locking operation to the clamp arm through the usage of either a wedge lock link mechanism or a toggle link mechanism. 
     Another object of the present invention is to provide a specially designed power clamp apparatus which utilizes a wedge lock system to move the clamp arm into a closed clamped position. 
     Another object of the invention is to provide a new power clamp mechanism which utilizes a straight extruded body, with no offsets or doglegs being present in the body of the clamp mechanism. 
     Another object of the invention is to provide a new power clamp mechanism capable of using at least three different types of clamp arms; namely, a U-arm, a side arm/U-arm, or a regular side arm type clamping bar. 
     Another object of the invention is to provide a unique new clamp mechanism wherein a unit assembly including a piston, a piston rod, a floating head member, and a link mechanism, are all assembled together prior to being inserted as a unit into the body of the clamp mechanism. 
     Another object of the invention is to provide a new clamp mechanism wherein a special track mechanism is used to guide the up-and-down movement of the piston rod to thereby provide a technically advanced and uniquely operative clamp mechanism. 
     Another object of the invention is to provide a novel clamp mechanism which is made using a single metal body and which includes a centrally located push-pull rod (or piston rod) which is generally centered in the middle of that single body, which houses the clamp mechanism, to thereby accomplish uniform force distribution and longevity for the clamp mechanism. 
     Another object of the invention is to provide a unique and novel clamp mechanism which utilizes a floating head mounted on the rigid tracks, which floating head when fixed in position within the clamp body acts as the upper cylinder head for the chamber (or cavity) within which the piston moves. 
     Other objects features and advantages of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates an exploded view of the power clamp mechanism in accordance with the invention which utilizes a wedge lock linkage mechanism to drive the clamp arm; 
     FIG. 2 illustrates another exploded view of the invention illustrating the use of a U-shaped clamp arm; 
     FIG. 3 illustrates another exploded view of the invention, basically the same as FIGS. 1-2, except taken from the opposite side thereof and with the track mechanism attached to the floating head; 
     FIG. 4 shows an interior view of the power clamp mechanism of the invention with the piston member being driven near to its top position within its piston chamber; 
     FIG. 5 illustrates a top view of the clamp mechanism of the invention in exploded view format; 
     FIG. 6 shows a view of the interior assembly of the clamp mechanism of the invention; 
     FIG. 7 shows another cross-sectional view of the clamp mechanism of the invention in partially cut-away cross-section; 
     FIG. 8 shows an alternate embodiment of the power clamp mechanism of the invention, which utilizes a toggle linkage mechanism to drive the shaft which rotates the clamp arm; 
     FIG. 9 shows a sectional view taken along the line  9 — 9  in FIG. 8; 
     FIG. 10 shows a top view of FIG. 8 partially in phantom view to show the interior workings of the FIG. 8 clamp mechanism; 
     FIG. 11 shows an enlarged view of the left end of FIG. 8, to show more detail of the toggle linkage mechanism used. 
     FIG. 12 shows a second alternate embodiment of a power clamp according to the present invention. 
     FIG. 13 shows a top end view of the second alternate embodiment of the power clamp. 
     FIG. 14 shows a cross section taken along the line A—A in FIG. 13 of the second alternate embodiment of the power clamp. 
     FIG. 15 shows a top end view of the power clamp according to the second alternate embodiment with the head cap removed. 
     FIG. 16 shows a cross section taken along line B—B in FIG. 15 of the power clamp according to the second alternate embodiment. 
     FIG. 17 shows an exploded view of a third alternate embodiment of the power clamp. 
     FIG. 18 shows a clamp mechanism with T-slots for mounting. 
    
    
     SUMMARY OF THE INVENTION 
     Briefly stated, the present invention involves a power clamp apparatus comprised of, a single metal body with an interior cavity running there through, a unit assembly which is inserted into said interior cavity, and said unit assembly including, a piston for slidable back and forth movement within said cavity, a lower portion of said cavity acting as a chamber for said piston, a piston rod connected to said piston, a floating head member attached to the rigid tracks, a link mechanism connected proximate to an upper end of said piston rod, a lower cap member which closes off said cavity near a bottom end of said metal body, an upper cap member which closes off the metal body proximate to a top end thereof after said unit assembly is inserted into said cavity, a drive shaft inserted through apertures in a generally transverse position through said metal body, with a central portion of said drive shaft inside the metal body being connected to an end of said link mechanism, a clamp arm attached to said drive shaft on the outside of said metal body, and wherein when said piston rod attached to said link mechanism is moved from its retracted position to its extended position, it causes the clamp arm to be moved between an open position and a clamped positioned relative to a work piece being clamped. 
     From another aspect, this invention involves a power clamp apparatus comprised of, a single body with an interior cavity running there through, a unit assembly which is inserted into said interior cavity, and said unit assembly including, a piston for slidable back and forth movement within said cavity, a lower portion of said cavity acting as a chamber for said piston, a piston rod connected to said piston, a floating head member through which the piston rod moves, a link mechanism connected proximate to an upper end of said piston rod, a lower cap member which closes off said cavity near a bottom end of said metal body, an upper cap member which closes off the metal body proximate to a top end thereof after said unit assembly is inserted into said cavity, a drive shaft inserted through apertures in a generally transverse position through said metal body, with a central portion of said drive shaft inside the metal body being connected to an end of said link mechanism, a clamp arm attached to said drive shaft on the outside of said metal body, and wherein when said piston rod attached to said link mechanism is moved from its retracted position to its extended position, it causes the clamp arm to be moved between an open position and a clamped positioned relative to a work piece being clamped. 
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The preferred embodiments of the invention are now to be described with reference to the drawings. Like numerals in different drawing figures indicate like elements. 
     FIGS. 1-7 show various exploded views of the power clamp mechanism designated  10 . In the clamp mechanism  10  there is utilized an elongated body member  12  which has a central cavity there through designated  14 . The body  12  has numerous holes or apertures therein designated  16 , which are used for mounting of the clamp body to a stationary surface (not shown), and which supports the clamp mechanism for working operation thereof. At each end of the clamp body  12  there is positioned a cap member, with the upper cap number being designated  18  and the lower cap number designated  20 . The interior of the power clamp mechanism  10  is basically comprised of a piston  30 , a piston rod  32 , a floating head  34  and a driven plate  36 . 
     The drive shaft  40  is shown in FIGS. 1,  2  and  3 , such that the drive shaft is positioned transversely through the two apertures  42  and  44 . The drive shaft  40  is typically supported for rotational movement by bearings designated  50 . Circular bushings (preferably made of steel or polymer materials) are pressed into the extruded body  12  at the apertures  42  and  44 ; and, then the metal bearings  50  (preferably sintered) are pushed over the square section drive shaft to mate with and be seated within the steel bushings. 
     The wedge lock linkage is designated  36 . The driven plate  36  or wedge lock linkage mechanism  36  is connected to the upper end of the piston rod  32  through usage of the clevis pin  64 . The clevis pin  64  is supported at the upper end of the piston rod  32  by the U-shaped frame member  64   a , which is mounted at the left end of the piston rod (see FIGS.  1 - 2 ). When the piston rod  32  is driven to its full upward position the wedge lock link is driven upwardly to rotate the square cross-section drive shaft such that the clamp arm  66  on the exterior of the clamp mechanism is rotated in a downward direction to thereby closed the clamp arm  66  against a work piece. 
     The piston  30  is driven in a back and forth direction, that is in an up-and-down direction, through introduction of hydraulic fluid or gases to the chamber  80  through use of the hydraulic inlet and outlet ports  82  and  84 . 
     The clamp arm  66  has its two recesses  67  and  69  placed over the complementary mating end portions  71  and  73  of the square cross-section drive shaft  40 , and once the clamp arm recesses  67  and  69  are placed thereover, the fastening plates  75  are secured (with fasteners) across the drive shaft  40  to hold the clamp arm  66  thereon. 
     The track mechanism is comprised of two tracks  91  and  93 . The track members  91  and  93  permit the slidable up-and-down movement of the rolling bearings  65  within the tracks  91  and  93  to properly align the up-and-down movement of the piston rod  32 . Also the lower portion of the track members  91  and  93  have small shoulder members  95  and  97  which buttress against the floating head  34  at the receiving ramps  103  and  105  (i.e., complementary receiving shoulder recesses thereon). 
     Once the internal workings of the clamp mechanism are inserted into the clamp body  12 , the track members  91  and  93  buttress up against the receiving ramps  103  and  105  (as best shown in FIG. 4) to position the floating head  34  in a stationary position; and, once so positioned the floating head then acts as the upper head for the piston chamber  80 . 
     FIG. 6 shows the internal working mechanism in assembled format, such that it is ready for insertion into the body  12 , that is, to the interior cavity  14  of the body  12 . Once the internal mechanism is inserted, then the drive shaft member  40  is positioned transversely through the openings  42 ,  44  to link with the wedge lock link mechanism  36 . 
     FIGS. 4 and 7 show cross-sectional views of the clamp mechanism  10 , with the unit assembly of FIG. 6 inserted therein, and with the drive shaft  40  being positioned through the transverse holes  42 ,  44 . 
     FIGS. 8,  9 ,  10  and  11  show an alternate embodiment of the invention wherein a toggle linkage mechanism is utilized to drive the shaft member  140 . In the toggle linkage version of the invention the piston rod  132  is connected to the lower portion of a toggle link  133 , which in turn is connected to another toggle link  135 . When the piston rod  132  is retracted, or moved in a downward direction, this pulls on the link member  133  to thereby also exert a pulling action on the link  135 , which rotates the drive shaft  140  into an open position to thereby open the clamp arm  166  (not shown). Likewise when the piston rod  132  is driven in an upward direction, the link  133  is rotated back to the position as shown in FIG. 11, to thereby force the link  35  to rotate the drive shaft  140 , which in turn closes or clamps the clamp arm  66  against a work piece. 
     Also as shown in FIGS. 8,  9 ,  10  and  11 , the top plate member  118  is of greatly strengthened capacity, as is necessary for the additional forces required when a toggle link mechanism  133 ,  135  is used in carrying out the invention. 
     There are many new and advantageous features of the power clamp mechanism disclosed herein. For example, the clamp mechanism of the invention utilizes a metal body with a cavity there through, and preferably this metal body is made from extruded metal. In some alternative embodiments, however, the metal body may be machined. When an extruded body is used, it is a single extruded metal body, instead of a separate body and attached cylinder; and this enables greatly lower cost of manufacturing for the clamp mechanism of the invention. Furthermore, this enables the clamp mechanism of the invention to be light weight and compact which are very important features for automotive tooling components. 
     As will be shown from the drawings herein, there is porting through the sides of the metal body to permit driving of the piston in an up-an-down movement to thereby power the clamp arm into an open or closed-locked position. There are also direct mounting holes drilled and tapped into the non-pressure portions of the clamp body, which enable the clamp mechanism to be mounted from either side thereof, or from the front and rear portions of the clamp mechanism as well. No CNC machining is required in preparing the clamp mechanism of the invention and this enables greatly lower cost of manufacturing. Still further the clamp body may be extruded with or without the four (4) longitudinal holes shown on the end caps thereof, and the end caps can be separately made such that the holes are drilled into the body after the extruding operation is carried out. 
     With respect to the porting holes or apertures in the clamp mechanism, the pressure ports can be located in the extruded body or in the end caps  18  and  20 . The porting holes can be from the sides, the front, or the back of the clamp body  12  or  112 . 
     The internal workings of the clamp mechanism (for example as shown in the left side of FIG. 1, or in FIG.  6 ), enables a single unit assembly, namely the pneumatic piston rod and dividing plate to be assembled outside the body of the clamp, and then the whole unit assembly is inserted into the metal body of the clamp. Also the internal mechanism is either supported by the end cap  18  (or fasteners which are inserted through the body) to locate and hold the mechanism. The divider plate, or floating head member  34 , is fastened to tracks  91  and  93  which in turn are fastened to the end cap  18 . The roller bearings  65  are used to facilitate the release of the clamp from a wedge linkage locked condition (or from a toggle linkage locked condition). The piston rod clevis can be either a separate unit or machined or formed onto the end of the piston rod  32  (or  132 ) itself 
     With respect to the drive shafts and/or bearings used to house the drive shaft, the drive shaft  40  is inserted through the body member  12  and through the driven plate. The drive shaft is generally made up of four parts instead of a single machining. Hardened steel bushings are pressed into the extruded body and centered, and then metal bearings are pushed over the square cross-section drive shaft to be seated (within the bushings) to thereby mount the drive shaft  40  for rotational movement, which in turn moves the clamp arm up-and-down from an open position to a locked position. The square drive shaft may need to be fastened to the drive plate with some means other than just a press fit to resist failure due to fatigue. If this is done small pins can be driven into the drive shaft to fasten it to the drive plate and this can be done just prior to closure of the upper cap member  18  onto the body member  12 . 
     With respect to the cap member  18 , on the wedge lock embodiment the cap supports the whole internal mechanism of track members, piston rod, floating head  34 , and piston  30 . The cap is made from a machining, investment casting, by a die casting, or by other similar process. The cap will have an opening through which a position sensor will be placed to monitor the extent to which the clamp arm is opened or closed to a locked position. The cap member  18  is then sealed off from the environment when the cap  18  is fixedly positioned to the end of the metal body member  12 . In the toggle linkage embodiment, the cap  118  member takes up extensive loading generated during toggling so that high loading is not put on the aluminum extrusion, from which the metal body member  12  is preferably made. 
     With respect to the sensor unit, the sensor unit is inserted from the top of the clamp mechanism, unlike other clamps where the unit is inserted from the back or front. The sensor unit may include an angle of opening adjustment so that the clamp owner can easily remove the sensor, change the chicklet position, and adjust the angle of opening of the clamp arm at the same time. The clamp mechanism has space allotted for the sensor/angle of adjustment feature. 
     With respect to T-slot mounting, the extrusion shape of the body member  12  permits the use of a single T-slot  19  or multiple T-slots located in the body member  12  or the body member  112  to facilitate mounting thereof, see FIG.  18 . This T-slot type mounting can replace or augment the technique of bolting and/or doweling the clamp to its work station. 
     A second alternate embodiment of a power clamp  210  according to the present invention is shown in FIGS. 12-16. The power clamp  210  includes an extruded clamp body  212  that generally has a rectangular shape. In this embodiment the clamp body  212  is an extruded metal material that includes an interior cavity  214  there through. In the second embodiment the shape of the interior cavity  214  is a true ellipse when viewed from an end or through cross section. It should be noted that the clamp body  212  can be extruded from any type of hard ceramic, plastic, aluminum or any other type of extrudable material but in the second embodiment metal is used. It should also be noted that in the preferred embodiment a rectangular shaped clamp body  212  is used but that any other shape capable of being extruded may be used depending on the clamp environment and design needs of the clamp operation. The extruded clamp body  212  also includes a plurality of orifices  216  on the sides of the clamp body  212 . The orifices  216  are used to connect to the work piece being clamped or to receive and hold drive shafts or other components for the power clamp  210 . 
     The power clamp  210  also includes an internal assembly which is inserted through one end of the clamp body  212  into the interior cavity  214 . The internal assembly is a single unitary member that is assembled separate from and outside of the clamp  210  and is then inserted as a single unitary member into the clamp body  212  from the top end. The internal assembly includes a piston  230  connected to a piston rod  232  on one end of the piston rod  232 . The piston rod  232  also has a head assembly  234  arranged on the opposite end of the piston rod  232  from the piston  230 . The piston rod  232  has a reduced radius portion  231  on one end thereof where the piston  230  connects thereto. The piston  230  includes a first and second seal plate  233 ,  235  which surround a first and second piston plate  237 ,  239  and a first seal anti-extrusion plate  241 . A first and second piston seal  243 ,  245  surround the outer edge or periphery of the piston  232  and are adjacent to the seal anti-extrusion plate  241 . The piston  232  is arranged on the reduced radius portion  231  of the piston rod  232  and is secured by any known securing means  247  in contact with a shoulder of the reduced portion of the piston rod  231  and connected by the securing means  247  on the end opposite of the shoulder. 
     The head assembly  234  is arranged on the opposite end of the piston rod  232  from the piston  230  and includes a seal plate  249  engaging a piston plate  251  on one end thereof. On the opposite end of the piston plate  251  a seal anti-extrusion plate  253  is engaged therewith. A piston seal  255  is placed around the outside of the piston plate  251  while a rod seal  257  is arranged between the outer circumference of the piston rod  232  and the inner circumference of the piston plate  25   1 . A track assembly  259  generally comprising a first and second track or channel  291 ,  293  which have their openings face one another is engaged with the seal anti-extrusion plate  253  of the head assembly  234  and is connected by any known means to the head assembly  234 . On the opposite end of the track assembly or member  259  is a first and second rivet  261 ,  263  which are used to connect to a head cap  218 . It should be noted that any other type of connecting device may be used, but in this embodiment a rivet is used. 
     A clevis  264  generally having a U-shape with an orifice  265  through each end thereof and an orifice  267  through its base is connected by any known securing means to the end of the piston rod  232  nearest the head assembly  234 . The clevis  264  also includes a roller pin  201  arranged in the orifices  265  at the top end of the clevis  264  with a roller bearing  203  attached to each end of the roller pin  201  at the outside surface of the clevis  264 . The clevis  264  is then inserted within the track assembly  259  such that the roller bearings  203  will roll along the first and second channels of the track assembly  259 . The clevis  264  is also, via the orifice  267 , connected via any known securing means  205 , in the second embodiment a screw is used to the end of the piston rod  232  nearest the head assembly  234 . 
     A drive plate  236  generally having a body  207  and an appendage  209  that extends therefrom is also a part of the internal assembly. The appendage  209  has a predetermined angle from a center line of the drive plate body  207 . The appendage  209  also includes a shoulder portion  211  that creates a stop for the power clamp  210 . The drive plate  236  has an orifice  213  through its body portion that mates with a drive shaft  240  male member for the power clamp  210 . A channel  215  is located in the appendage  209  of the drive plate  236  and is arranged such that the roller pin  201  is placed through the channel  215  and allows for the drive plate  236  to be connected to the clevis  264  which is located within the track assembly  259 . It should also be noted that a toggle link may also be used according to this second alternate embodiment. 
     The power clamp  210  also includes in the second alternate embodiment a two piece drive shaft  240  that generally has a square cross section, however it should be noted that any other type of shape such as round or any other known shape may be used for the drive shaft  240 . The second alternate embodiment also could use a one piece drive shaft  240  or any other number of pieces depending on the design and needs of the clamp environment. The first and second members  217 ,  219  of the drive shaft  240  engage with and are non-rotatably secured within the orifice  213  of the drive plate  236  such that any rotational movement of the drive shaft  240  will also cause rotation of the drive plate  236 . The drive shaft  240  is supported within the clamp body  210  by a first and second bushing  251  and a first and second bearing  250 . The bushing  251  and bearings  250  are located through a first and second orifice  242 ,  244  on the sides of the clamp body  212 . In the second embodiment the bearings  250  are made of a Teflon material but any other known type of bearing may also be used depending on the design and needs of the power clamp  210  and its environment. The first member  217  of the drive shaft  240  includes an orifice through the entire length thereof The second member  219  of the drive shaft  240  includes a threaded orifice through a predetermined portion. After insertion in the power clamp  210 , any known securing means, a screw  221  in this embodiment is placed through the first member  217  of the drive shaft and secured into the second drive shaft member  219 . 
     The power clamp  210  also includes an end cap  220  located on a bottom end of the clamp body  212 . The end cap  220  is sealed by a gasket  223  between the end cap  220  and the clamp body  212 . In the second alternate embodiment the internal unitary assembly is placed through the top end of the extruded body clamp  212  into the interior cavity  214  until the piston rod  232  engages with the end cap  220  of the clamp body  212 . Then the drive shaft  240  is inserted through the first and second orifice  242 ,  244  of the clamp body  212  and its two pieces  217 ,  219  are connected to each other and supported by the bearings  250  and bushings  251 . The two pieces  217 ,  219  also engage with and are secured within the orifice  213  of the drive plate  236 . Finally, a head cap  218  is connected to the clamp body  212  after being centered by any known appropriate means to the center line of the ellipse or other shape of the cavity. It should be noted that the cavity in the second alternate embodiment is a true ellipse but that any other known shape such as a circle or oval or any other known extrudable shape may be used. The head cap  218  is connected by rivets  261 ,  263  to the end of the track assembly  259  opposite the head assembly  234 . A gasket may also be used between the head cap  218  and the end of the clamp body  212 . 
     After completion of the assembly of the clamp  210  a clamp arm  66  is connected via the first and second bushings  251  to the drive shaft  240 , thus allowing for automatic or manual operation of the power clamp  210  by a computer, machine or manual operation. In operation when the clamp is in an open position the piston  230  is located near the end cap  220 , within the cavity portion defined as the piston chamber  280 . The piston chamber  280  is defined by the head assembly  234  and the end cap  220 . When the clamp  210  is put into its closed position the clamp arm  66  is rotated by a rotation of the drive shaft  240 . The drive shaft  240  is rotated by the drive plate  236 , i.e., the roller pin  201  will move within the channel  215  of the drive plate appendage  209  until the shoulder portion  211  of the appendage contacts a surface of the head cap  218 . Once the shoulder portion contacts the surface of the head cap  218  a positive stop for the power clamp  210  is created thus securing the power clamp  210  in its closed position. The piston  230  will slide axially towards the head assembly  234  when the power clamp  210  is moving to its closed position, due to the hydraulic pressures acting on the piston  230 , those pressures will also hold the power clamp  210  in its closed position. Therefore, the design of the clamp  210  can be changed such that the angle of the channel through the appendage  209  of the drive plate  236  creates a quicker movement towards the positive stop of the power clamp  210  thus reducing the axial movement of the piston  230  within the piston chamber  280  and reducing the forces necessary to hold the clamp or increase the forces necessary to hold the clamp in a closed position. The roller bearings  203  and clevis  264  have axial movement within the track assembly  259  due to the forces being translated by the piston rod  232 . 
     In assembling the power clamp  210  according to the second alternate embodiment, first the metal body  212  is extruded with an ellipse shaped cavity  214  there through. Next, the internal clamp assembly is assembled and the head cap  218  is attached to an end of the track member  259 . Next, the end cap  220  is connected to the clamp body  212  on a bottom end of the clamp body. Then, the one unitary internal clamp assembly, which was pre-built, is inserted through the top end of the clamp body  212  into the cavity  214  until the end of the piston rod  232  engages the inside surface of the end cap  220 . Then, the drive shaft  240  is inserted into the clamp body  212  and engages with the drive plate  236  of the internal clamp assembly such that the drive plate  236  is non-rotatably connected to the drive shaft  240 . Finally, the head cap  218  is secured to the clamp body  212  by positioning the head cap  218  with respect to the center line of the ellipse of the interior cavity  214  and not by the outer surfaces of the head cap  218  with respect to the outer surfaces of the clamp body  212 . 
     FIG. 17 shows a third alternate embodiment of the clamp  310  according to the present invention and operates in the same manner as that described for FIGS. 12-16. 
     While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects, benefits, and/or advantages of the invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.