CA1267166A - Clamping device - Google Patents
Clamping deviceInfo
- Publication number
- CA1267166A CA1267166A CA000519861A CA519861A CA1267166A CA 1267166 A CA1267166 A CA 1267166A CA 000519861 A CA000519861 A CA 000519861A CA 519861 A CA519861 A CA 519861A CA 1267166 A CA1267166 A CA 1267166A
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- CA
- Canada
- Prior art keywords
- members
- plate
- cam
- pivot
- arm
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
CLAMPING DEVICE
ABSTRACT
This invention is an improved concept of the clamp shown in U. S. No. 3,736,629, as issued June 5, 1973. This clamping device has two C-shaped arms, each of which is an assembly of two plate-like members of sheet metal. These two arm assem-blies are pivotally retained at one end, with the plate like members in an overlay condition. A pivot pin has an enlarged center portion which acts as a spacer and has two eccentric cam areas sized and spaced to actuate apertures formed in one of the arm pairs. Shouldered rivets retain these arm assem-blies in spaced array and a stop pin secured in this pivot pin has a length sufficient to engage a secured rivet. At one limit of movement of the stop pin, the cam areas move one arm assembly to a maximum clamping force and, at the other limit of movement of the stop pin, the cam areas are in a reduced-force application. Trunnion blocks are pivotally retained in each arm, with one block having through threads and the other block having a smooth bore adapted to retain a socket-headed cap screw whose threaded portion is compatibly disposed in the threaded trunnion. Rotation of this screw causes jaw ends having pivoted clamp pads to be brought to and away from each other. The members of this clamp are of metal and the pivot pin and clamp pads may be made by a screw machine and then heat-treated.
ABSTRACT
This invention is an improved concept of the clamp shown in U. S. No. 3,736,629, as issued June 5, 1973. This clamping device has two C-shaped arms, each of which is an assembly of two plate-like members of sheet metal. These two arm assem-blies are pivotally retained at one end, with the plate like members in an overlay condition. A pivot pin has an enlarged center portion which acts as a spacer and has two eccentric cam areas sized and spaced to actuate apertures formed in one of the arm pairs. Shouldered rivets retain these arm assem-blies in spaced array and a stop pin secured in this pivot pin has a length sufficient to engage a secured rivet. At one limit of movement of the stop pin, the cam areas move one arm assembly to a maximum clamping force and, at the other limit of movement of the stop pin, the cam areas are in a reduced-force application. Trunnion blocks are pivotally retained in each arm, with one block having through threads and the other block having a smooth bore adapted to retain a socket-headed cap screw whose threaded portion is compatibly disposed in the threaded trunnion. Rotation of this screw causes jaw ends having pivoted clamp pads to be brought to and away from each other. The members of this clamp are of metal and the pivot pin and clamp pads may be made by a screw machine and then heat-treated.
Description
~x~
CI,AMPI NG D~V ICE
Tile tool which is the subject of this application is known as a llalld clamp. The name probably derives from the fact that it is applied by hand rather than by any power-enhancirlg means SUCtl as air or hydraulic pressure, but it is also true that in mo~t cases a clamp serves as a surrogate human hand, to apply and maintain pressure where and as required. Hand clamps take many forms, some highly specialized; vi2~ clamps for holding picture frames square for nailing, or for holding two pipe ends in alignment for welding, and as such having little or no other use~ul purpose. The variety of such special clamps is probably in the several hundreds, many of which have been the subject of patents.
The Eundamental di~ferences between the device of U. S.
Patent No. ~,736,G29 and that of this disclosure, aside from component design changes dictated by a need to reduce produc-tion costs at some minor loss of utility, are two: In place of th~ ~asher~ e component of the original clamping device which, in conjunction with a small pin projecting from the ~0 side of the cam, limited the cam's rotation (a system which was expensive to produce and presented the possibility of pin-shearing in use), the improved design provides a sturdy cross-pin in the cam member, rotation of which is limited by the adjacent spacer-rivets joining the jawplates. The second area of improvement is in the direction in which camming force is applied: In the original design, the cam~.ing action spread the opposing iaws on a ~ine parallel to the adjusting sc~ew.
~n the improved d~sign, the ja~ opposite the scre~ head is merely a br~ce, ~orce being applied to the ja~ und~r the screw 33 head perpendicularly to an imaginary line drawn between the ~2~
pivot center of the trunnion block under the screw head and the pivot center oE th~e cam member. This change in dire~tion of force provides a leveraye improvement of over 39%.
Thus, this invention may be summarized, at least in part, with reEerence to its objects. It is an object of this inven-tion to provide, and it does provide, an improved clamping device in which a pair of C-shaped arm members is pivotally retained at one end in an overlaid arrangement and with their other ends with pivotally-retained pressure pads. Intermediate the ends of these arm members there is disposed an adjusting screw tha~ is adjusted to not only provide -the desired distance, but also to provide the primary force-applying means and the force-retaining means. The plVOt pin at the one end of the arms has cam surfaces to provide a selective pressure adjustment of -the gripping pads at the other end of the arm.
A further object of this inven-tion is to provide, and it does provide, a clamping mechanism in which two pivo-ted C-shaped arms are pivotaily retained in an overlaid condition and position at one end, with thls pivot having cam means. The other ends of 20; the arms are provided with pivotally-re-tained, inwarùly--directed clamping pads adapted to re-tain the workpiece. Near the mid-length oE each arm is positioned a rotatable screw with pivot-able retaining means, said screw haviny a threaded portion that is carried in a threaded, pivoted-retaining means on one arm so as to ~ove the arms toward or away from each other to bring the pads into retaining condition and apply primary pressure. The pivot cam at the overlaid ends is turned to provide maximum ; clamp force. This clamp thus provides a rugged device that is easily manipulated to exer-t the desired holding action. This clamp is easily assembled from stamped steel arms, rivets and ~7~
hardened screw machine members.
A preferred co~struc-tion oE this invention is described in detail below wi-th reference to the drawings which illustrate only olle specific embodiment in which:
FIG. 1 represents an exploded isometric view, partly diagram-matic, and showing relative placement or positioning of the com-ponents as used in the clamping device of this invention;
FIG. 2 represents a top or plan view oE the clamping device of FIG. 1 with the several components i~ an~assembled condition lQ and with the jaws in a substan-tially opened condition;
FIG. 3 represen-ts the clamping device of FIG. 2 with the jaw ends brought together;
FIG. 4 represents a diagrammatic pl~an view in a greatly enlarged scale and showing the eccentric cam:portions as formed on this pivot pin member, this view absent the arm portions and taRen on the line 4 - 4 o:f FIG. 5 and looking in the direction of the arrows;
FIG. 5 represents a diagratnmatic and sectional side view in ; the enLarged scale of FIG. 4 and showing the eccen-tric portions formed on the pivot pin, this view taken on the line 5 - 5 of FIG. 2 and looking in the direction of the arrows;
-FIG. 6 represents a fragmentary side and sectional view, partly diagrammatic, and showing the preEerred arrangement of mèmbers, with this view taken on the line 6 - 6 of FIG. 2 and looking in the direction of the arrows;
FIG. 7 represents a side sectional view, partly diagramma-tic, ;: and showiny the midlength adjusting screw, this view taken on -the line 7 - 7 of FIG. 2 and looking in the direction of the arrows;
.
6~;
FIG. 8 A represents a diagrammatic view oE the limit or stop pin as moved to a "cam free" condition, with the pressure pads adjusted to the outer limit and with the screw head to the left;
FIG. 8 B represen-ts the view of FIG. 8 A, but with -the pres-sure pads adjustably rnoved -to inner limi-ts;
FIG. 8 C represents the view of FIG. 8 A, bu-t with the stop pln moved to bring the cam into a "tight" condi-tion, and FIG. 8 D represen-ts the view of FIG. 8 B, but with the pres-sure pads adjustably moved into an inner condilion and the pin moved to bring the cam into a l'tight" condi-tion.
Referring now to the drawings as brieEly described above, the several components a~e shown in FIG. 1. In this ~iew, ik is to be noted that a socket-headed cap screw, generally identi-fied as 10, is shown as extendlng from the right, whereas in FIGS. 2 and 3 the knurled head of this screw is depicted on -the left. This showing position is intended to particularly empha-size -tha~ the clamping device oE this invention may be used with the head of -the screw of the clampin~ device in ei-ther attitude.
The head end Oe this screw conven-tionally has therein ~. hex ¦ 20 socket 11, although other conEigurations may be provided. To the left of this head and in and on -the shank portion thereof is formed a ~hallow groove 12 spaced a given dis-tance from the head. A thread 13 is cgnventlonally -formed on this cap screw.
A trunnion bloclc~ generaLly identified as 1~, has a hole 15 therethrQugh. This hole is ~ sliding fit on the shank of the screw 10. The -thickne~s or width (right ~o Left) of the trun-; nion bloc]c 1~ is jus~ a fçw th~usand~h$ of an inch less than the distance fro~ the shoulder Oe -the head of screw 10 to the shallow yroove 12. A retaining ring or washer 16 is adpated -to be moun-ted in -this groove 12 to retain this trunnion block 14 1~67~66 on the shanlc oE the screw 10. 'I'runnion block 1~ as shown has two pivot pins 17~which provide pivoted movemen-t and also reten-tion of -this block.
As depicted in FIG. 1, the right C-shape arm movement in-cludes stamped and formed sheet-metal members, generally identi-fied as 20 and 21, each of which is provided with inwardly-direc-ted ofEset portions 20 a and 21 a. Extending downwardly from these offset portions are the major portions of -these arms.
These portions are identiEied as 20 b and 21 b. It is to be noted -that in each arm component there are formed rivet holes 23, 24 and 25. These holes may or may not be of a like size, but are sized to be a snug fit for the reduced ends of the rive-ts used to provide the assembly. Spacer-rivets 27, 28 and 29 are depic-ted. Each arm portion 20 b and 21 b also has holes 30 which are sized to rotatably retain the pivot pins 17 formed on the trunnion bloclc 14. Also shown and pivotally carried by rivet 29 is clamp pad 32 which has a hole 33 -through which this rivet passes. It is -to be noted that the lower ends oE the arms 20 and 21 are contoured so that the movement of clamp pad 32 may be li.mlted, thereby assurinq proper orientation oE the pacl Eace with the wor~piece.
A threaded trunnion block 35 has threads 36 that are compa-t-ible with threads 13 on cap screw 10. Pivot pin portions 37 are also provided as in block 14. Another retaining ring or washer 38 is adapted to be secured in a groove 39 formed in and at the terminal end of the sc~ew 10.
The left arm also, as an assembly, employs two C-shaped sheet-s-teel members. These members are generally identified as 41 and 42. The upper ends have outwardly-directed oEfset por-tions 41 a and 42 a. Ex-tending downwardly from -these oEfset ~26~
portions are the major portions 41 b and 42 b o~ the C-shaped arms. As in the ~igh-t arm assembly, -there are Eormed in each member three rivet holes, respectively identifed as ~5, 46 and 47. Rivets 48, 49 and 50 are used -to secure these plates in spaced array. The spacing is provided by the larger cen-tral por-tion of all rivets. Trunnion block 35 is movable between these secured plates ~1 and 42 and rotates about pivot pin portions 37 which are rotatably mounted in like holes 52 formed in pla-tes 41 and 42. On the lower end of this arm assembly is clamp pad 54 having a through hole 55 providing a pivoting ac-tion ahout rivet 50. The lower ends of members 41 and 42 are contoured as in 20 and 21 to provide a limited movement of khe clamp pad 5~.
A pivot cam, generally identified as 60, is better described in conjunction with the showing in FIGS. 4 and 5. This is con-templated to be a screw machine part with a hex aper-ture 62 -therethrough which is best seen in FIG. 4. As depicted in FIGS. 4 and 5, this pivot cam has a central larger body portion 63 and reduced end portions 64 and 65. In these reduced por-tions are Eormed like eccentric cam areas 66 a and 66 b. These cam areas are particularly formed and have a wid-th to actuate the arm portions 20 and 21. A stop pin 68 is mounted and secured in a transverse hole in the pivot cam 60 to provide means, in conjunction with the body portions of rivets 27 and 48, to limit the movement oE pivot cam 60. The forming of this pivot cam and the eccentric cam portions 66 and the transverse hole ~or stop pin 68 is calculated precisely, and in FIGS. 8 A, B, C and D the relationship of the several Eormed por-tions of this pivot cam is shown and discussed.
The arm members are provided wi-th apertures for mounting and actuation oE the pivot cam 60. In 20 a there is depicted i6 aperture 70 and in 21 a there is depicted aperture 71. In arm ~1 a there is for~ed a through aperture 73 and in arm 42 a -there is ~ormed aperture 74. These aper-tures are oE like size. The several other holes in the arm members are of other like diame-ters. It is conte~plated -tha-t the C-shaped arm members will be made with a single die, and with another die offsets are formed so that the arms 20 and 21 will be offset -to form an inner spacing and -the ar~s ~1 and ~2 ~rill be offset to form an ou-ter spacing in which the arm ends overlay one another as seen in FIG. 5.
It is to be noted that rivet 27 is shorter than rivets 28 and 29 as this rivet is used to retain the inwardly-directed offset portions 20 a and 21 a of the C-shaped arm members. In like manner, rivet 48 is diPferent from the other rivets in that it has the body portion lengthened to accommodate the outward oEfsets ~1 a and 42 a oE the other C-shaped arm members. The several rivet holes may be of like or diEferent diameters and are merely a matter o~ sele~ction. As viewed in FIG. 1, holes 25 and 47, which retain the ends of rivets 24 and 50, are slightl~ smaller than the diame-ter of holes 23, 24, 45 and ~6, but this is merely a mat-ter of selection. All -trunnion block holes for the pin portions provided thereon are like size. The stop pin 68 for limiting -the cam rotation is a dowel or commer-cial pin member such as a roll pin. Rive-ts 28, 29, ~9 and 50 are contemplated to be alike in length as arm portions 20 b, 21 b, ~1 b and 42 b in the assembled condition are in parallel array and move in like and the same planes.
In FIG. 2, the screw head is shown to the left and the clamp is de~picted in a partially open condition, about two-t~irds oE
capaci-ty. As can be seen, the threaded portion 13 of screw 10 ~l2~
still has some wa~ to go. As depicted, the stop pin 68 is mid-way of stop limits as pr'ovided by secured rive-ts 27 and 48.
A discussion oE -the pivot cam 60 will be made here'inafter.
In FIG. 3, the clamping device of FIG. 2 is repeated, but with the clamp pads 32 and 5~ in substantially a closed condi-tion and with the stop pin 68 still in the condition oE FIG. 2.
In the showing of FIG. ~, which is very fraymen-tary and in an enlarged scale, the pivot cam 60 is shown in a plan view clearly depicting a hex passageway 62. Other configura-tions 0 may be used as this through passageway is merely a matter oE
selection and convenience as most machine shops have hex wrenches (Allen-type). A hex wrench is also used with the screw 10. An aperture is formed in this pivot cam in which is tigh-tly moun-ted stop pin 68. The eccentric cam portion 66 is - particularly formed in relation to this stop pin 68. This relationship is more fully discussed later in conjunction wi-th FIGS. 8 A, B, C and D. It is to bs noted tha-t s-top pin 68 pro-vides a seat Eor insertion oE a hex wrench into the pivot cam 60 Eor final ti~htening from either side.
The cLampiny device as shown in FIG. 5, when assembled, u-til-izes the pivot pin 60 and the cam portions 66 a and 66 b to pro-vide the desired application oE clamping force. The upper off-set portions ~1 a and 42 a are shown disposed as outer arm por-tions. These arm portions and the apertures 73 and 79 therein rotata~ly engage the reduced diameter 64 as formed on the pivot cam. Immediately inside of~sets 41 a and '12 a and parallel to and slideable thereby are inner offset portions 20 a and 21 a.
These ends also have apertures'70 and 71 which are the same size as the apertures 73 and 7~ in the other two outer members.
These apertures 70 and 71 are slideable past diameter 6~ and 1~'7~
rest on the enlar~ed diame-ter 63 of the pivot pin. These aper-tures 70 and 71 e~gage and move in -the eccen-tric yrooves 66 a and 66 b formed in this pivot pin 60. The stop pin 68 is shown substantially mid~ay of the hex passageway 62 formed in said pivot pin.
In FIG. 6, a fragmen-tary sectional vie~ is provided to illus-trate the relationship of the threaded trunnion 35 with the pivot pin portions 37 in holes 52 in pla-tes 41 and 42. Rivet 50 is depicted pivotally retaining clamp pad 54. Rivet 49 is also shown securing and providing the spacing of and for arm plates ~1 and ~2.
In FIG. 7, a sectional ~iew taken on the line 7 - 7 of FIG. 2 is depicted -to illustrate that the clamping device in an assem-bled condition is adapted to lie flat and be used with -the adjusting screw head ei-ther to the leEt or to the right. Shown in this view are retaining rings 16 and 38 mounted on screw 10.
The a~m members 20 and 21 are shown as substantially in the same plane as arm members 41 and ~2. The -trunnion block 1~ and the threaded -trunnion blocl~ 35 are also shown. The rivets 27 and ~8 are also seen and provide limit stops for the manipula-tion of the stop or limit pin 68 seen in FIGS. 4 and 5 above.
Referring finally to FIGS. 8 A, 8 B, 8 C and 8 D, these FIGS.
are merely a diayrammatic showing of the pivot cam of a clamp of about -three-inch maximum opening. In these drawings-diagrams, the dimensions are for a three-inch maximum clamp, which diagrams are illustrati-ve of said clamp. In these FIGS., the precise relationship of the pivot cam to the stop pin 68, the C-shaped arms and the rivet stops is noted. It is to be noted that rivets 27 and 48 establish the limits of rotative movement of stop pin 68.
6~
In FIG. 8 A is shown the relationship of the cam portion 66 to the stop pin 6~ and assuming -the head of screw 10 is on the lef-t. In this FIG., the C-shaped arms have been moved -to sub-stantially the maximum opening, with the trunnion pivots 17 and 37 about four inches apart. As seen, stop pin 68 is swung to the left to -the limit establishe~ by rivet 27.~ For comparison of sizes, the body oE the rivet is three-eighths of an inch in di~meter and is sevèn-eigh-ths oE an inch on cen-ters from -the center of pivot eln 60. The diameter oE -the stop pin 68 is con-templated -to be three-eighths of an inch in diameter and, in the angles and dimensions as noted, the size or diame-ter of this stop pin is very important as to -the actuating relationship.
Assuming a theoretical line 80 parallel to line 31, which is the theoretical line between trunnion pins 17 and 37, stop pin 68 is about ten and ane-~uarter degrees, identified as included angle 82. The lowes-t point oE cam 66 is at an angle 83 oE about Eorty-Eour degrees, which is about the same as angle 85 from a theoretical center line to a trunnion pivot. These assumed dimensions contemplate that the screw center line at this show-ing is slightly more than two and one-sixteenth inches from the screw center line 81 to the center of the pivot cam 60.
In FIG. 8 B, the adjus-tin~ screw lO has brough-t the clamp jaw ends 32 and 54 into a together condition as depicted in FIG. 3, but with the stop pin 68 moved into the leftward limit-.
ing position a~ainst rivet 27. The stop ~in 68, ra-ther than above the theoretical horizontal line 80, is now below (-toward the screw) and with about the same amoun-t oE swing, identiEied as 87. It is to be noted that trunnion pins 17 and 37 have moved toward each other -to about two and three-tenths inches therebetween. The rivets 27 and 48 have been cor~espondingly moved so that, whereas the angle in FIG. 8 A was about EiE-teen and one-half degrees, this angle is about thir-ty~six degrees.
This angle is identiEied as 88. The lowest poin-t of the cam, rather than -the angle 83 of FIG. 8 A, is now about twenty-three and one-half degrees and is identiEied as 89. The cam's low poin-t is always perpendicu].ar to a line drawn Erom the center of the cam 60 to the center of the trunnion 17. Wi-th the movirly oE
the trunnions closer together, the distance from the center line of the screw to the center of the pivot pin is increased and is about two and five-eigh-ths inches.
In FIG. 8 C, the arrangement of the trunnion spacing of FIG.
8 A is repea-ted, but with -the stop pin 68 swung so that it now is against rivet ~8. The cam portion 66 has been moved so -tha-t the high point of the cam bearing is about forty-Eou~ degrees ~identified as 90) above the horizontal line and left of -the verti~al center line. The direction of force swinging the jaw 32 in-to the workpiece is supplied by this high po.r-tion of the cam.
In FIG. 8 D, the arranyement of -the trunnion spacing of FLG.
8 B is repeated, but the stop pin is shown as swung to the right against rivet 48. The cam portion 66 now brings the high point oE the cam in position to move the jaw 32 into the worlspiece gripping condition. The direction oE force, identiEied as 92, is about twenty-three and one-halE degrees.
It is to be noted tha-t the cam 66 formed in pivot pin 60 has abou-t a sixty-degree Eull-diameter dwell area. The purpose of -this Eeature is to compensate for the di-Efering angles of FIG.
8 C, 90, and FIG. 8 D, 92, and infini-tely -therebe-tween. Thus, when the clamping device is ful1y open and cam 66 is in the full, "tight" position, FIG. 3 C, the full diameter of cam 66 is ~à7~
entered upon about nine and one-half degrees. When the clampin~
device is fully c~osed and cam 66 is in -the Eull, "tight" posi-tion, FIG. 8 D, -the sixty degree Eull-diameter dwell area is ~ithin about nine and one-half degrees of being overridden. The purpose of this dwell area is to prevent such override bu-t, in practice, it is only necessary to rotate the cam sufficiently to enter upon the dwell area to achieve Eull force.
It is also to be noted -that the pivot pin 60 has the hex pas-sageway 62 comple-gely therethrough. This permits tightening of -the clamping device from either side, as necessary or convenient It is also perceived -to be desirable in the manufacturing proc-ess, aEEorcling a means of orienting the pivot pin 60 Eor forming the transverse hole for stop pin 68 and forming the cam surfaces 66 in proper rela-tionship to one another.
All measuremen-ts and degrees are noted for a clamping device of about three-inch maximurn opening, bu-t variations may be made to suit the designer and producer, and such sugges-ted dimensions are not lirnitiny.~
It is realized that although illustrated as forming the arm assemblies of like blanking and starnping dies, one arm assembly may be made withou-t offset end portions. Such an arrangement would resultin altering the positioning of the apertures for the pivot pin. The illus~rated offse-t allows the C-shaped arm mem-bers to be blanked and punche~ f~om the same die and ~hen to be offset the same amount, which is one~hal~ the thickness oE the metal sheet used for the$e arm members. The rive-ts are usually of plated steel a~d the reduced ends are made of suEFicient ex-tended length for rivet forming oE the re-tained ends. The - pressure pads are pivotally retained by rivets. In an assembled condi-tion, the l~wer portions of eacn arm member lie in parallel . . .
~lX~7~
or the same planes.
As shown in FI~S. 8 A, 8 B, 8 C and 8 D, the eccentric cam portlons 66 are forrned -to provide dwell portion 91 which, as noted, is about sixty degrees. ~his dwell, identiEie~ as 91, is Eormed as a result of not forming the eccentric cam areas as circular, but only about three hundred degrees of arc. This dwell as described above provides the abili-ty of u-tilizing this clamp for workpieces oE various thicknesses from -the very -thin -to substan~ially maximum opening, with the adjustment allowing movement of the stop arm 68 Erom open to a closed condition.
, This clamping device as made and assembled is believed to provide a novel method of construction and assembly, which includes -the steps of;
- Eorming and assembling a pair of C-shaped arms;
- pivotally retaining a pair oE C-shaped arm assemblies at one end and at the other end of each arm assembly re-taining a pressure clamp pad, with each arm assembly oE two substan-tially alilce plate-lilce members of metal, and arranying and maintaining said members in spaced array by spacer and securing means, and at the pivotally-retained end disposing these arms in overlaid condition, and in each plate forming a pivot aperture, with -the formed apertures disposed for axial alignment;
positioning and retaining a pivot cam at one end oE the overlapped arm members and forming on this pivot cam two eccen--tric cam surfaces sized ~to be engaged with each of the apertured surfaces of the two plate-like members of only one of the pair of arms and forming -the intermediate portion of the pivot cam with an enlarged portion si~ed to be slideably retained between -the smallest distance between pla-te-like arm members when in overlaid condition;
~2~71~i - forming a pair of trunnion blocks with pivot portions and mountin~ one trunr~ion block so as to be pivotally car.ried between said plate-like members in each arm, and posi-tioning each trun-nion block intermediate the extent o:E the C-shaped arm assemblies with each block disposed to be a precisely equal distance from the axis of the mounted pivot cam, one trunnion block having threads formed therein and the other trunnion block having a smooth bore therethrough;
- mounting in the trunnion blocks a threaded cap screw having a head member adapted for rotative manipulation and having a shank portion wi-th a threaded end portion, with these threads compatible with -those threads in the threaded trunnion block, and providing limitiny means for longitudinal retention ofthe cap screw in that -trunnion block having a smoo-th bore and inserting -the threads on the cap screw in the threads Eormed in the threaded trunnion block, said cap screw providiny an adjust-ing means and a force member that ~rings the pressure clamp pads toward and away from each other;
- mounting a first rivet near the pivot cam, said rivet having an enlarged midportion of a determined size and length so as -to establish and maintain the plate-like members of a first arm in spaced a.rray, and securing this first rivet at a precise location and distance from the axis of the pivot cam;
- mounting a se~ond rivet near the pivot cam, this second rivet also having an enlarged midportion of a size like that pro-vided by the Eirst rivet, this second rivet having a lenyth so as to establish and maintain the plate-like members of -this other clamp arm in spaced array, and securing this second rivet at a precise location and distance from the axis oE the pivot cam, the f:irst and second rivets so positioned that their axes establish a t~leoretical ~ine therebetween so as to be always parallel to a the~oretical line through the pivot axes of the trunnion blocks, said first and second rivets and their precise :location at a like distance from the axis of the pivot cam;
- mounting ano-ther pair of rivets, each having enlarged midportions, one rivet positioned in said first arm a.ssembly adjacent a trunnion block, and another similar rivet positioned in the other a~m assembly and also adjacent the trunnion block in said other arm assembly, and - forming a hole and fixedly inserting in said hole a stop pin in the enlarged portion of the pivot cam, this stop pin of sufficien-t length so that said stop pin as i-t is swung in an arc is limited by said first or second rivet, this stop pin being secured so -that -when the stop pin engages one of the first or second rivets, the cam surfaces formed on the pivot cam engage the apertures in that arm assembly disposed to be actuated by the eccentric cam, -the maxlmum throw of the arm assembly moviny the pressure clarnp pads closer toyether and, when the stop pin is moved to the other limit, the clamp pads are moved away from each other.
CI,AMPI NG D~V ICE
Tile tool which is the subject of this application is known as a llalld clamp. The name probably derives from the fact that it is applied by hand rather than by any power-enhancirlg means SUCtl as air or hydraulic pressure, but it is also true that in mo~t cases a clamp serves as a surrogate human hand, to apply and maintain pressure where and as required. Hand clamps take many forms, some highly specialized; vi2~ clamps for holding picture frames square for nailing, or for holding two pipe ends in alignment for welding, and as such having little or no other use~ul purpose. The variety of such special clamps is probably in the several hundreds, many of which have been the subject of patents.
The Eundamental di~ferences between the device of U. S.
Patent No. ~,736,G29 and that of this disclosure, aside from component design changes dictated by a need to reduce produc-tion costs at some minor loss of utility, are two: In place of th~ ~asher~ e component of the original clamping device which, in conjunction with a small pin projecting from the ~0 side of the cam, limited the cam's rotation (a system which was expensive to produce and presented the possibility of pin-shearing in use), the improved design provides a sturdy cross-pin in the cam member, rotation of which is limited by the adjacent spacer-rivets joining the jawplates. The second area of improvement is in the direction in which camming force is applied: In the original design, the cam~.ing action spread the opposing iaws on a ~ine parallel to the adjusting sc~ew.
~n the improved d~sign, the ja~ opposite the scre~ head is merely a br~ce, ~orce being applied to the ja~ und~r the screw 33 head perpendicularly to an imaginary line drawn between the ~2~
pivot center of the trunnion block under the screw head and the pivot center oE th~e cam member. This change in dire~tion of force provides a leveraye improvement of over 39%.
Thus, this invention may be summarized, at least in part, with reEerence to its objects. It is an object of this inven-tion to provide, and it does provide, an improved clamping device in which a pair of C-shaped arm members is pivotally retained at one end in an overlaid arrangement and with their other ends with pivotally-retained pressure pads. Intermediate the ends of these arm members there is disposed an adjusting screw tha~ is adjusted to not only provide -the desired distance, but also to provide the primary force-applying means and the force-retaining means. The plVOt pin at the one end of the arms has cam surfaces to provide a selective pressure adjustment of -the gripping pads at the other end of the arm.
A further object of this inven-tion is to provide, and it does provide, a clamping mechanism in which two pivo-ted C-shaped arms are pivotaily retained in an overlaid condition and position at one end, with thls pivot having cam means. The other ends of 20; the arms are provided with pivotally-re-tained, inwarùly--directed clamping pads adapted to re-tain the workpiece. Near the mid-length oE each arm is positioned a rotatable screw with pivot-able retaining means, said screw haviny a threaded portion that is carried in a threaded, pivoted-retaining means on one arm so as to ~ove the arms toward or away from each other to bring the pads into retaining condition and apply primary pressure. The pivot cam at the overlaid ends is turned to provide maximum ; clamp force. This clamp thus provides a rugged device that is easily manipulated to exer-t the desired holding action. This clamp is easily assembled from stamped steel arms, rivets and ~7~
hardened screw machine members.
A preferred co~struc-tion oE this invention is described in detail below wi-th reference to the drawings which illustrate only olle specific embodiment in which:
FIG. 1 represents an exploded isometric view, partly diagram-matic, and showing relative placement or positioning of the com-ponents as used in the clamping device of this invention;
FIG. 2 represents a top or plan view oE the clamping device of FIG. 1 with the several components i~ an~assembled condition lQ and with the jaws in a substan-tially opened condition;
FIG. 3 represen-ts the clamping device of FIG. 2 with the jaw ends brought together;
FIG. 4 represents a diagrammatic pl~an view in a greatly enlarged scale and showing the eccentric cam:portions as formed on this pivot pin member, this view absent the arm portions and taRen on the line 4 - 4 o:f FIG. 5 and looking in the direction of the arrows;
FIG. 5 represents a diagratnmatic and sectional side view in ; the enLarged scale of FIG. 4 and showing the eccen-tric portions formed on the pivot pin, this view taken on the line 5 - 5 of FIG. 2 and looking in the direction of the arrows;
-FIG. 6 represents a fragmentary side and sectional view, partly diagrammatic, and showing the preEerred arrangement of mèmbers, with this view taken on the line 6 - 6 of FIG. 2 and looking in the direction of the arrows;
FIG. 7 represents a side sectional view, partly diagramma-tic, ;: and showiny the midlength adjusting screw, this view taken on -the line 7 - 7 of FIG. 2 and looking in the direction of the arrows;
.
6~;
FIG. 8 A represents a diagrammatic view oE the limit or stop pin as moved to a "cam free" condition, with the pressure pads adjusted to the outer limit and with the screw head to the left;
FIG. 8 B represen-ts the view of FIG. 8 A, but with -the pres-sure pads adjustably rnoved -to inner limi-ts;
FIG. 8 C represents the view of FIG. 8 A, bu-t with the stop pln moved to bring the cam into a "tight" condi-tion, and FIG. 8 D represen-ts the view of FIG. 8 B, but with the pres-sure pads adjustably moved into an inner condilion and the pin moved to bring the cam into a l'tight" condi-tion.
Referring now to the drawings as brieEly described above, the several components a~e shown in FIG. 1. In this ~iew, ik is to be noted that a socket-headed cap screw, generally identi-fied as 10, is shown as extendlng from the right, whereas in FIGS. 2 and 3 the knurled head of this screw is depicted on -the left. This showing position is intended to particularly empha-size -tha~ the clamping device oE this invention may be used with the head of -the screw of the clampin~ device in ei-ther attitude.
The head end Oe this screw conven-tionally has therein ~. hex ¦ 20 socket 11, although other conEigurations may be provided. To the left of this head and in and on -the shank portion thereof is formed a ~hallow groove 12 spaced a given dis-tance from the head. A thread 13 is cgnventlonally -formed on this cap screw.
A trunnion bloclc~ generaLly identified as 1~, has a hole 15 therethrQugh. This hole is ~ sliding fit on the shank of the screw 10. The -thickne~s or width (right ~o Left) of the trun-; nion bloc]c 1~ is jus~ a fçw th~usand~h$ of an inch less than the distance fro~ the shoulder Oe -the head of screw 10 to the shallow yroove 12. A retaining ring or washer 16 is adpated -to be moun-ted in -this groove 12 to retain this trunnion block 14 1~67~66 on the shanlc oE the screw 10. 'I'runnion block 1~ as shown has two pivot pins 17~which provide pivoted movemen-t and also reten-tion of -this block.
As depicted in FIG. 1, the right C-shape arm movement in-cludes stamped and formed sheet-metal members, generally identi-fied as 20 and 21, each of which is provided with inwardly-direc-ted ofEset portions 20 a and 21 a. Extending downwardly from these offset portions are the major portions of -these arms.
These portions are identiEied as 20 b and 21 b. It is to be noted -that in each arm component there are formed rivet holes 23, 24 and 25. These holes may or may not be of a like size, but are sized to be a snug fit for the reduced ends of the rive-ts used to provide the assembly. Spacer-rivets 27, 28 and 29 are depic-ted. Each arm portion 20 b and 21 b also has holes 30 which are sized to rotatably retain the pivot pins 17 formed on the trunnion bloclc 14. Also shown and pivotally carried by rivet 29 is clamp pad 32 which has a hole 33 -through which this rivet passes. It is -to be noted that the lower ends oE the arms 20 and 21 are contoured so that the movement of clamp pad 32 may be li.mlted, thereby assurinq proper orientation oE the pacl Eace with the wor~piece.
A threaded trunnion block 35 has threads 36 that are compa-t-ible with threads 13 on cap screw 10. Pivot pin portions 37 are also provided as in block 14. Another retaining ring or washer 38 is adapted to be secured in a groove 39 formed in and at the terminal end of the sc~ew 10.
The left arm also, as an assembly, employs two C-shaped sheet-s-teel members. These members are generally identified as 41 and 42. The upper ends have outwardly-directed oEfset por-tions 41 a and 42 a. Ex-tending downwardly from -these oEfset ~26~
portions are the major portions 41 b and 42 b o~ the C-shaped arms. As in the ~igh-t arm assembly, -there are Eormed in each member three rivet holes, respectively identifed as ~5, 46 and 47. Rivets 48, 49 and 50 are used -to secure these plates in spaced array. The spacing is provided by the larger cen-tral por-tion of all rivets. Trunnion block 35 is movable between these secured plates ~1 and 42 and rotates about pivot pin portions 37 which are rotatably mounted in like holes 52 formed in pla-tes 41 and 42. On the lower end of this arm assembly is clamp pad 54 having a through hole 55 providing a pivoting ac-tion ahout rivet 50. The lower ends of members 41 and 42 are contoured as in 20 and 21 to provide a limited movement of khe clamp pad 5~.
A pivot cam, generally identified as 60, is better described in conjunction with the showing in FIGS. 4 and 5. This is con-templated to be a screw machine part with a hex aper-ture 62 -therethrough which is best seen in FIG. 4. As depicted in FIGS. 4 and 5, this pivot cam has a central larger body portion 63 and reduced end portions 64 and 65. In these reduced por-tions are Eormed like eccentric cam areas 66 a and 66 b. These cam areas are particularly formed and have a wid-th to actuate the arm portions 20 and 21. A stop pin 68 is mounted and secured in a transverse hole in the pivot cam 60 to provide means, in conjunction with the body portions of rivets 27 and 48, to limit the movement oE pivot cam 60. The forming of this pivot cam and the eccentric cam portions 66 and the transverse hole ~or stop pin 68 is calculated precisely, and in FIGS. 8 A, B, C and D the relationship of the several Eormed por-tions of this pivot cam is shown and discussed.
The arm members are provided wi-th apertures for mounting and actuation oE the pivot cam 60. In 20 a there is depicted i6 aperture 70 and in 21 a there is depicted aperture 71. In arm ~1 a there is for~ed a through aperture 73 and in arm 42 a -there is ~ormed aperture 74. These aper-tures are oE like size. The several other holes in the arm members are of other like diame-ters. It is conte~plated -tha-t the C-shaped arm members will be made with a single die, and with another die offsets are formed so that the arms 20 and 21 will be offset -to form an inner spacing and -the ar~s ~1 and ~2 ~rill be offset to form an ou-ter spacing in which the arm ends overlay one another as seen in FIG. 5.
It is to be noted that rivet 27 is shorter than rivets 28 and 29 as this rivet is used to retain the inwardly-directed offset portions 20 a and 21 a of the C-shaped arm members. In like manner, rivet 48 is diPferent from the other rivets in that it has the body portion lengthened to accommodate the outward oEfsets ~1 a and 42 a oE the other C-shaped arm members. The several rivet holes may be of like or diEferent diameters and are merely a matter o~ sele~ction. As viewed in FIG. 1, holes 25 and 47, which retain the ends of rivets 24 and 50, are slightl~ smaller than the diame-ter of holes 23, 24, 45 and ~6, but this is merely a mat-ter of selection. All -trunnion block holes for the pin portions provided thereon are like size. The stop pin 68 for limiting -the cam rotation is a dowel or commer-cial pin member such as a roll pin. Rive-ts 28, 29, ~9 and 50 are contemplated to be alike in length as arm portions 20 b, 21 b, ~1 b and 42 b in the assembled condition are in parallel array and move in like and the same planes.
In FIG. 2, the screw head is shown to the left and the clamp is de~picted in a partially open condition, about two-t~irds oE
capaci-ty. As can be seen, the threaded portion 13 of screw 10 ~l2~
still has some wa~ to go. As depicted, the stop pin 68 is mid-way of stop limits as pr'ovided by secured rive-ts 27 and 48.
A discussion oE -the pivot cam 60 will be made here'inafter.
In FIG. 3, the clamping device of FIG. 2 is repeated, but with the clamp pads 32 and 5~ in substantially a closed condi-tion and with the stop pin 68 still in the condition oE FIG. 2.
In the showing of FIG. ~, which is very fraymen-tary and in an enlarged scale, the pivot cam 60 is shown in a plan view clearly depicting a hex passageway 62. Other configura-tions 0 may be used as this through passageway is merely a matter oE
selection and convenience as most machine shops have hex wrenches (Allen-type). A hex wrench is also used with the screw 10. An aperture is formed in this pivot cam in which is tigh-tly moun-ted stop pin 68. The eccentric cam portion 66 is - particularly formed in relation to this stop pin 68. This relationship is more fully discussed later in conjunction wi-th FIGS. 8 A, B, C and D. It is to bs noted tha-t s-top pin 68 pro-vides a seat Eor insertion oE a hex wrench into the pivot cam 60 Eor final ti~htening from either side.
The cLampiny device as shown in FIG. 5, when assembled, u-til-izes the pivot pin 60 and the cam portions 66 a and 66 b to pro-vide the desired application oE clamping force. The upper off-set portions ~1 a and 42 a are shown disposed as outer arm por-tions. These arm portions and the apertures 73 and 79 therein rotata~ly engage the reduced diameter 64 as formed on the pivot cam. Immediately inside of~sets 41 a and '12 a and parallel to and slideable thereby are inner offset portions 20 a and 21 a.
These ends also have apertures'70 and 71 which are the same size as the apertures 73 and 7~ in the other two outer members.
These apertures 70 and 71 are slideable past diameter 6~ and 1~'7~
rest on the enlar~ed diame-ter 63 of the pivot pin. These aper-tures 70 and 71 e~gage and move in -the eccen-tric yrooves 66 a and 66 b formed in this pivot pin 60. The stop pin 68 is shown substantially mid~ay of the hex passageway 62 formed in said pivot pin.
In FIG. 6, a fragmen-tary sectional vie~ is provided to illus-trate the relationship of the threaded trunnion 35 with the pivot pin portions 37 in holes 52 in pla-tes 41 and 42. Rivet 50 is depicted pivotally retaining clamp pad 54. Rivet 49 is also shown securing and providing the spacing of and for arm plates ~1 and ~2.
In FIG. 7, a sectional ~iew taken on the line 7 - 7 of FIG. 2 is depicted -to illustrate that the clamping device in an assem-bled condition is adapted to lie flat and be used with -the adjusting screw head ei-ther to the leEt or to the right. Shown in this view are retaining rings 16 and 38 mounted on screw 10.
The a~m members 20 and 21 are shown as substantially in the same plane as arm members 41 and ~2. The -trunnion block 1~ and the threaded -trunnion blocl~ 35 are also shown. The rivets 27 and ~8 are also seen and provide limit stops for the manipula-tion of the stop or limit pin 68 seen in FIGS. 4 and 5 above.
Referring finally to FIGS. 8 A, 8 B, 8 C and 8 D, these FIGS.
are merely a diayrammatic showing of the pivot cam of a clamp of about -three-inch maximum opening. In these drawings-diagrams, the dimensions are for a three-inch maximum clamp, which diagrams are illustrati-ve of said clamp. In these FIGS., the precise relationship of the pivot cam to the stop pin 68, the C-shaped arms and the rivet stops is noted. It is to be noted that rivets 27 and 48 establish the limits of rotative movement of stop pin 68.
6~
In FIG. 8 A is shown the relationship of the cam portion 66 to the stop pin 6~ and assuming -the head of screw 10 is on the lef-t. In this FIG., the C-shaped arms have been moved -to sub-stantially the maximum opening, with the trunnion pivots 17 and 37 about four inches apart. As seen, stop pin 68 is swung to the left to -the limit establishe~ by rivet 27.~ For comparison of sizes, the body oE the rivet is three-eighths of an inch in di~meter and is sevèn-eigh-ths oE an inch on cen-ters from -the center of pivot eln 60. The diameter oE -the stop pin 68 is con-templated -to be three-eighths of an inch in diameter and, in the angles and dimensions as noted, the size or diame-ter of this stop pin is very important as to -the actuating relationship.
Assuming a theoretical line 80 parallel to line 31, which is the theoretical line between trunnion pins 17 and 37, stop pin 68 is about ten and ane-~uarter degrees, identified as included angle 82. The lowes-t point oE cam 66 is at an angle 83 oE about Eorty-Eour degrees, which is about the same as angle 85 from a theoretical center line to a trunnion pivot. These assumed dimensions contemplate that the screw center line at this show-ing is slightly more than two and one-sixteenth inches from the screw center line 81 to the center of the pivot cam 60.
In FIG. 8 B, the adjus-tin~ screw lO has brough-t the clamp jaw ends 32 and 54 into a together condition as depicted in FIG. 3, but with the stop pin 68 moved into the leftward limit-.
ing position a~ainst rivet 27. The stop ~in 68, ra-ther than above the theoretical horizontal line 80, is now below (-toward the screw) and with about the same amoun-t oE swing, identiEied as 87. It is to be noted that trunnion pins 17 and 37 have moved toward each other -to about two and three-tenths inches therebetween. The rivets 27 and 48 have been cor~espondingly moved so that, whereas the angle in FIG. 8 A was about EiE-teen and one-half degrees, this angle is about thir-ty~six degrees.
This angle is identiEied as 88. The lowest poin-t of the cam, rather than -the angle 83 of FIG. 8 A, is now about twenty-three and one-half degrees and is identiEied as 89. The cam's low poin-t is always perpendicu].ar to a line drawn Erom the center of the cam 60 to the center of the trunnion 17. Wi-th the movirly oE
the trunnions closer together, the distance from the center line of the screw to the center of the pivot pin is increased and is about two and five-eigh-ths inches.
In FIG. 8 C, the arrangement of the trunnion spacing of FIG.
8 A is repea-ted, but with -the stop pin 68 swung so that it now is against rivet ~8. The cam portion 66 has been moved so -tha-t the high point of the cam bearing is about forty-Eou~ degrees ~identified as 90) above the horizontal line and left of -the verti~al center line. The direction of force swinging the jaw 32 in-to the workpiece is supplied by this high po.r-tion of the cam.
In FIG. 8 D, the arranyement of -the trunnion spacing of FLG.
8 B is repeated, but the stop pin is shown as swung to the right against rivet 48. The cam portion 66 now brings the high point oE the cam in position to move the jaw 32 into the worlspiece gripping condition. The direction oE force, identiEied as 92, is about twenty-three and one-halE degrees.
It is to be noted tha-t the cam 66 formed in pivot pin 60 has abou-t a sixty-degree Eull-diameter dwell area. The purpose of -this Eeature is to compensate for the di-Efering angles of FIG.
8 C, 90, and FIG. 8 D, 92, and infini-tely -therebe-tween. Thus, when the clamping device is ful1y open and cam 66 is in the full, "tight" position, FIG. 3 C, the full diameter of cam 66 is ~à7~
entered upon about nine and one-half degrees. When the clampin~
device is fully c~osed and cam 66 is in -the Eull, "tight" posi-tion, FIG. 8 D, -the sixty degree Eull-diameter dwell area is ~ithin about nine and one-half degrees of being overridden. The purpose of this dwell area is to prevent such override bu-t, in practice, it is only necessary to rotate the cam sufficiently to enter upon the dwell area to achieve Eull force.
It is also to be noted -that the pivot pin 60 has the hex pas-sageway 62 comple-gely therethrough. This permits tightening of -the clamping device from either side, as necessary or convenient It is also perceived -to be desirable in the manufacturing proc-ess, aEEorcling a means of orienting the pivot pin 60 Eor forming the transverse hole for stop pin 68 and forming the cam surfaces 66 in proper rela-tionship to one another.
All measuremen-ts and degrees are noted for a clamping device of about three-inch maximurn opening, bu-t variations may be made to suit the designer and producer, and such sugges-ted dimensions are not lirnitiny.~
It is realized that although illustrated as forming the arm assemblies of like blanking and starnping dies, one arm assembly may be made withou-t offset end portions. Such an arrangement would resultin altering the positioning of the apertures for the pivot pin. The illus~rated offse-t allows the C-shaped arm mem-bers to be blanked and punche~ f~om the same die and ~hen to be offset the same amount, which is one~hal~ the thickness oE the metal sheet used for the$e arm members. The rive-ts are usually of plated steel a~d the reduced ends are made of suEFicient ex-tended length for rivet forming oE the re-tained ends. The - pressure pads are pivotally retained by rivets. In an assembled condi-tion, the l~wer portions of eacn arm member lie in parallel . . .
~lX~7~
or the same planes.
As shown in FI~S. 8 A, 8 B, 8 C and 8 D, the eccentric cam portlons 66 are forrned -to provide dwell portion 91 which, as noted, is about sixty degrees. ~his dwell, identiEie~ as 91, is Eormed as a result of not forming the eccentric cam areas as circular, but only about three hundred degrees of arc. This dwell as described above provides the abili-ty of u-tilizing this clamp for workpieces oE various thicknesses from -the very -thin -to substan~ially maximum opening, with the adjustment allowing movement of the stop arm 68 Erom open to a closed condition.
, This clamping device as made and assembled is believed to provide a novel method of construction and assembly, which includes -the steps of;
- Eorming and assembling a pair of C-shaped arms;
- pivotally retaining a pair oE C-shaped arm assemblies at one end and at the other end of each arm assembly re-taining a pressure clamp pad, with each arm assembly oE two substan-tially alilce plate-lilce members of metal, and arranying and maintaining said members in spaced array by spacer and securing means, and at the pivotally-retained end disposing these arms in overlaid condition, and in each plate forming a pivot aperture, with -the formed apertures disposed for axial alignment;
positioning and retaining a pivot cam at one end oE the overlapped arm members and forming on this pivot cam two eccen--tric cam surfaces sized ~to be engaged with each of the apertured surfaces of the two plate-like members of only one of the pair of arms and forming -the intermediate portion of the pivot cam with an enlarged portion si~ed to be slideably retained between -the smallest distance between pla-te-like arm members when in overlaid condition;
~2~71~i - forming a pair of trunnion blocks with pivot portions and mountin~ one trunr~ion block so as to be pivotally car.ried between said plate-like members in each arm, and posi-tioning each trun-nion block intermediate the extent o:E the C-shaped arm assemblies with each block disposed to be a precisely equal distance from the axis of the mounted pivot cam, one trunnion block having threads formed therein and the other trunnion block having a smooth bore therethrough;
- mounting in the trunnion blocks a threaded cap screw having a head member adapted for rotative manipulation and having a shank portion wi-th a threaded end portion, with these threads compatible with -those threads in the threaded trunnion block, and providing limitiny means for longitudinal retention ofthe cap screw in that -trunnion block having a smoo-th bore and inserting -the threads on the cap screw in the threads Eormed in the threaded trunnion block, said cap screw providiny an adjust-ing means and a force member that ~rings the pressure clamp pads toward and away from each other;
- mounting a first rivet near the pivot cam, said rivet having an enlarged midportion of a determined size and length so as -to establish and maintain the plate-like members of a first arm in spaced a.rray, and securing this first rivet at a precise location and distance from the axis of the pivot cam;
- mounting a se~ond rivet near the pivot cam, this second rivet also having an enlarged midportion of a size like that pro-vided by the Eirst rivet, this second rivet having a lenyth so as to establish and maintain the plate-like members of -this other clamp arm in spaced array, and securing this second rivet at a precise location and distance from the axis oE the pivot cam, the f:irst and second rivets so positioned that their axes establish a t~leoretical ~ine therebetween so as to be always parallel to a the~oretical line through the pivot axes of the trunnion blocks, said first and second rivets and their precise :location at a like distance from the axis of the pivot cam;
- mounting ano-ther pair of rivets, each having enlarged midportions, one rivet positioned in said first arm a.ssembly adjacent a trunnion block, and another similar rivet positioned in the other a~m assembly and also adjacent the trunnion block in said other arm assembly, and - forming a hole and fixedly inserting in said hole a stop pin in the enlarged portion of the pivot cam, this stop pin of sufficien-t length so that said stop pin as i-t is swung in an arc is limited by said first or second rivet, this stop pin being secured so -that -when the stop pin engages one of the first or second rivets, the cam surfaces formed on the pivot cam engage the apertures in that arm assembly disposed to be actuated by the eccentric cam, -the maxlmum throw of the arm assembly moviny the pressure clarnp pads closer toyether and, when the stop pin is moved to the other limit, the clamp pads are moved away from each other.
Claims (21)
1. A clamping device for gripping a workpiece or workpieces between pivotally retained clamp pads disposed at the distal ends of a pair of pivotally-retained arms, this clamping device including:
(a) a pair of C-shaped arm assemblies pivotally retained at one end and at the other end of each arm assembly having a pivotally-retained pressure clamp pad, each arm assembly of two substantially alike plate-like members of metal arranged and maintained in spaced array by spacer and securing means, and at the pivotally-retained end these arms are disposed to be in overlaid condition, and in each plate there is formed an aper-ture, with the apertures disposed for axial alignment;
(b) a pivot cam disposed at and retaining one end of the C-shaped arms, this pivot cam formed with two eccentric cam sur-faces sized to be engaged with each of the apertured surfaces of the two plate-like members of only one of the pair of arms and with the intermediate portion of the pivot cam having an enlarged portion sized to be slideably retained between the smallest dis-tance between plate-like members when in overlaid condition, the mounted pivot cam having its axis normal to the C-shaped arms;
(c) a trunnion block pivotally carried between said plate-like members in each arm, cash trunnion block intermediate the extent of the C-shaped arm assemblies and each block disposed to be a precisely equal distance from the axis of the mounted pivot cam, one trunnion block having threads formed therein and the other trunnion block having a smooth bore therethrough, each trunnion block having means for pivotally mounting each block in the arm structure;
(d) a threaded cap screw having a head member adapted for rotative manipulation and having a shank portion with a threaded end portion, with these threads compatible with the threads in the threaded trunnion block, and limiting means for longitudinal retention of the cap screw in that trunnion block having a smooth bore and the threads on the cap screw compati-ble in the threads formed in the threaded trunnion block, said cap screw when and as mounted in said trunnion blocks providing an adjusting means and a force member that brings the pressure clamp pads toward and away from each other;
(e) a first spacer retainer having an enlarged midportion of a determined size and length so as to establish and maintain the plate-like members of a first arm in spaced array, and means for securing this retainer at a precise location and dis-tance from the axis of the pivot cam;
(f) a second spacer retainer having an enlarged midportion of a size like that provided by the first spacer retainer, this second spacer retainer having a length so as to establish and maintain the plate-like members of this other clamp arm in spaced array, and means for securing this second spacer retainer at a precise location and distance from the axis of the pivot cam, the first and second spacer retainers so positioned that their axes establish a theoretical line therebetween so as to be always parallel to a theoretical line through the pivot axes of the trunnion blocks, said first and second spacer retainers and their precise location at a like distance from the axis of the pivot cam;
(g) another pair of spacer retainers, each having enlarged midportions, one spacer retainer positioned in said first arm assembly adjacent a trunnion blocks, and another similar spacer retainer positioned in the other arm assembly and also adjacent the trunnion block in said other arm assembly, each spacer retainer disposed between the plate-like members so as to estab-lish and maintain the desired spacing, and (h) a stop pin fixedly secured in the enlarged portion of the pivot cam and of sufficient length so that the stop pin as it is swung in an arc is limited by said first or second spacer retainers, this stop pin being secured so that when the stop pin engages one of the spacer retainers, the cam surfaces formed on the pivot cam engage the apertures in that arm assembly disposed to be actuated by the eccentric cam, the maximum throw of the arm assembly moving the pressure clamp pads closer together and, when the stop pin is moved to the other limit, the clamp pads are moved away from each other.
(a) a pair of C-shaped arm assemblies pivotally retained at one end and at the other end of each arm assembly having a pivotally-retained pressure clamp pad, each arm assembly of two substantially alike plate-like members of metal arranged and maintained in spaced array by spacer and securing means, and at the pivotally-retained end these arms are disposed to be in overlaid condition, and in each plate there is formed an aper-ture, with the apertures disposed for axial alignment;
(b) a pivot cam disposed at and retaining one end of the C-shaped arms, this pivot cam formed with two eccentric cam sur-faces sized to be engaged with each of the apertured surfaces of the two plate-like members of only one of the pair of arms and with the intermediate portion of the pivot cam having an enlarged portion sized to be slideably retained between the smallest dis-tance between plate-like members when in overlaid condition, the mounted pivot cam having its axis normal to the C-shaped arms;
(c) a trunnion block pivotally carried between said plate-like members in each arm, cash trunnion block intermediate the extent of the C-shaped arm assemblies and each block disposed to be a precisely equal distance from the axis of the mounted pivot cam, one trunnion block having threads formed therein and the other trunnion block having a smooth bore therethrough, each trunnion block having means for pivotally mounting each block in the arm structure;
(d) a threaded cap screw having a head member adapted for rotative manipulation and having a shank portion with a threaded end portion, with these threads compatible with the threads in the threaded trunnion block, and limiting means for longitudinal retention of the cap screw in that trunnion block having a smooth bore and the threads on the cap screw compati-ble in the threads formed in the threaded trunnion block, said cap screw when and as mounted in said trunnion blocks providing an adjusting means and a force member that brings the pressure clamp pads toward and away from each other;
(e) a first spacer retainer having an enlarged midportion of a determined size and length so as to establish and maintain the plate-like members of a first arm in spaced array, and means for securing this retainer at a precise location and dis-tance from the axis of the pivot cam;
(f) a second spacer retainer having an enlarged midportion of a size like that provided by the first spacer retainer, this second spacer retainer having a length so as to establish and maintain the plate-like members of this other clamp arm in spaced array, and means for securing this second spacer retainer at a precise location and distance from the axis of the pivot cam, the first and second spacer retainers so positioned that their axes establish a theoretical line therebetween so as to be always parallel to a theoretical line through the pivot axes of the trunnion blocks, said first and second spacer retainers and their precise location at a like distance from the axis of the pivot cam;
(g) another pair of spacer retainers, each having enlarged midportions, one spacer retainer positioned in said first arm assembly adjacent a trunnion blocks, and another similar spacer retainer positioned in the other arm assembly and also adjacent the trunnion block in said other arm assembly, each spacer retainer disposed between the plate-like members so as to estab-lish and maintain the desired spacing, and (h) a stop pin fixedly secured in the enlarged portion of the pivot cam and of sufficient length so that the stop pin as it is swung in an arc is limited by said first or second spacer retainers, this stop pin being secured so that when the stop pin engages one of the spacer retainers, the cam surfaces formed on the pivot cam engage the apertures in that arm assembly disposed to be actuated by the eccentric cam, the maximum throw of the arm assembly moving the pressure clamp pads closer together and, when the stop pin is moved to the other limit, the clamp pads are moved away from each other.
2. A clamping device as in claim 1 which further includes making each plate-like member with a substantially identical con-figuration and apertures and with an upper end which provides at the overlaid end an offset, which extent is about one-half the thickness of the material used in the making of each plate-like member.
3. A clamping device as in claim 2 in which the pivot cam is formed with a through hexagonal aperture and with the smaller diameter end portions of the pivot cam rotatable in like diameter apertures formed in the upper extent of each plate-like member.
4. A clamping device as in claim 3 in which the stop pin secured in the pivot cam is a dowel, roll pin and the like, with said stop pin of sufficient length to extend a short distance beyond the retainer spacer and with this stop pin extending through the hexagonal aperture to establish two substantially like length hexagonal sockets.
5. A clamping device as in claim 4 in which the spacer retainers are rivet-like members with central portions larger than through holes formed in the plate-like arm members and with said rivet-like members having reduced end portions that are sized to snugly enter and pass through said through holes.
6. A clamping device as in claim 5 in which each of the trunnion blocks includes pivot pin portions which are integral with said block.
7. A clamping device as in claim 2 in which the first and second spacer retainers are rivets having like enlarged central portions and reduced ends sized to snugly enter and pass through holes formed in the plate-like arm members and with the ends of said rivets formed to secure said rivets in these formed holes, one rivet having a longer central portion to accommodate an assembly having -the offset producing two farther-apart ends and with the other rivet having a shorter central portion to accom-modate the offset producing two closer-together ends.
8. A clamping device as in claim 7 in which the pair of spacer retainers adjacent the trunnion blocks is like rivets with enlarged central portions and having reduced diameter end portions sized to snugly enter and pass through holes formed in the plate-like members, with said holes farther distant from the pivot axis than the trunnion blocks.
9. A clamping device as in claim 1 in which each of the clamp pads is of hardened steel with rounded workpiece-sripping pad portions and with reduced diameter shank portions sized to be retained between the fixed plate-like members and with the reduced diameter portions formed with a transverse hole sized to rotatably retain the central portion of a rivet whose ends are mounted in and pass through holes formed in the end portions of the plate-like arm member portions and are then riveted.
10. A clamping device as in claim 9 in which the limiting means for longitudinal retention of the threaded cap screw is provided by having a head that is less in diameter than the distance of the plate-like members that form the C-shaped arm assemblies, said head formed with a shoulder terminating with a shank portion sized to be rotatably retained in the smooth bore formed in the trunnion block, the shoulder providing a limiting longitudinal movement control against the outside face of said trunnion, and a retainer removably mounted in a groove formed in the shank of the cap screw, this retainer, when mounted in the groove in the shank, engaging the inner face of the trunnion block.
11. A clamping device as in claim 10 in which there is also a groove formed in the threaded cap screw and near the outer end of the threaded portion, this groove having a retainer mounted therein and providing an outer stop to movement of the threaded trunnion block outwardly along the thread portion of the cap screw.
12. A clamping device as in claim 1 in which the two eccen-tric cam surfaces on the pivot cam are formed adjacent the intermediate enlarged portion, said cam surfaces having a width substantially the thickness of the metal material providing the plate-like members, and adjacent these eccentric cam portions the pivot cam has a diameter rotatable in apertures formed in said plate-like members.
13. A clamping device as in claim 12 in which the two eccen-tric cam surfaces produce the same exact throw actuation on the inner plate-like end members in secured assembly and alignment and adapted to engage said cam surfaces.
14. A clamping device as in claim 13 in which the eccentric cam portions are formed in approximately three hundred degrees of are and the remaining sixty degrees providing a dwell portion.
15. A method of forming and assembling a clamping device for gripping a workpiece or workpieces between clamp pads disposed at the distal ends of a pair of pivotally-retained arms, these steps including:
(a) pivotally retaining a pair of C-shaped arm assemblies at one end and at the other end of each arm assembly retaining a pressure clamp pad, with each arm assembly of two substantially alike plate-like members of metal, and arranging and maintaining said members in spaced array by spacer and securing means, and at the pivotally-retained end disposing these arms in overlaid condition, and in each plate forming a pivot-aperture, with the formed apertures disposed for axial alignment;
(b) positioning and retaining a pivot cam at one end of the overlapped arm members and forming on this pivot cam two eccen-tric cam surfaces sized to be engaged with each of the aper-tured surfaces of the two plate-like members of only one of the pair of arms and forming the intermediate portion of the pivot cam with an enlarged portion sized to be slideably retained between the smallest distance between plate-like arm members when in overlaid condtion;
(c) forming a pair of trunnion blocks with pivot portions and mounting one trunnion block so as to be pivotally carried between said plate-like members in each arm, and positioning each trunnion block intermediate the extent of the C-shaped arm assemblies, with each block disposed to be a precisely equal distance from the axis of the mounted pivot cam, one trunnion block having threads formed therein and the other trunnion block having a smooth bore therethrough;
(d) mounting in the trunnion blocks a threaded cap screw having a head member adapted for rotative manipulation and having a shank portion with a threaded end portion, with these threads compatible with those threads in the threaded trunnion block, and providing limiting means for longitudinal retention of the cap screw in that trunnion block having a smooth bore and inserting the threads on the cap screw in the threads formed in the threaded trunnion block, said cap screw providing an adjusting means and a force member that brings the pressure clamp pads toward and away from each other;
(e) mounting a first rivet near the pivot cam, said rivet having an enlarged midportion of a determined size and length so as to establish and maintain the plate-like members of a first arm in spaced array, and securing this first rivet at a precise location and distance from the axis of the pivot cam;
(f) mounting a second rivet near the pivot cam, this second rivet also having an enlarged midportion of a size like that provided by the first rivet, this second rivet having a length so as to establish and maintain the plate-like members of this other clamp arm in spaced array, and securing this second rivet at a precise location and distance from the axis of the pivot cam, the first and second rivets so positioned that their axes establish a theoretical line therebetween so as to be always parallel to a theoretical line through the pivot axes of the trunnion blocks, said first and second rivets and their precise location at a like distance from the axis of the pivot cam;
(g) mounting another pair of rivets, each having enlarged midportions, one rivet positioned in said first arm assembly adjacent a trunnion block, and another similar rivet positioned in the other arm assembly and also adjacent the trunnion block in said other arm assembly, and (h) forming a hole and fixedly inserting in said hole a stop pin in the enlarged portion of the pivot cam, this stop pin of sufficient length so that said stop pin as it is manipulated comes in way of said first or second rivet, this stop pin being secured so that when the stop pin engages one of the first or second rivets, the cam surfaces formed on the pivot cam engage the apertures in that arm assembly disposed to be actuated by the eccentric cam, the maximum throw of the arm assembly moving the pressure clamp pads closer together and, when the stop pin is moved to the other limit, the clamp pads are moved away from each other.
(a) pivotally retaining a pair of C-shaped arm assemblies at one end and at the other end of each arm assembly retaining a pressure clamp pad, with each arm assembly of two substantially alike plate-like members of metal, and arranging and maintaining said members in spaced array by spacer and securing means, and at the pivotally-retained end disposing these arms in overlaid condition, and in each plate forming a pivot-aperture, with the formed apertures disposed for axial alignment;
(b) positioning and retaining a pivot cam at one end of the overlapped arm members and forming on this pivot cam two eccen-tric cam surfaces sized to be engaged with each of the aper-tured surfaces of the two plate-like members of only one of the pair of arms and forming the intermediate portion of the pivot cam with an enlarged portion sized to be slideably retained between the smallest distance between plate-like arm members when in overlaid condtion;
(c) forming a pair of trunnion blocks with pivot portions and mounting one trunnion block so as to be pivotally carried between said plate-like members in each arm, and positioning each trunnion block intermediate the extent of the C-shaped arm assemblies, with each block disposed to be a precisely equal distance from the axis of the mounted pivot cam, one trunnion block having threads formed therein and the other trunnion block having a smooth bore therethrough;
(d) mounting in the trunnion blocks a threaded cap screw having a head member adapted for rotative manipulation and having a shank portion with a threaded end portion, with these threads compatible with those threads in the threaded trunnion block, and providing limiting means for longitudinal retention of the cap screw in that trunnion block having a smooth bore and inserting the threads on the cap screw in the threads formed in the threaded trunnion block, said cap screw providing an adjusting means and a force member that brings the pressure clamp pads toward and away from each other;
(e) mounting a first rivet near the pivot cam, said rivet having an enlarged midportion of a determined size and length so as to establish and maintain the plate-like members of a first arm in spaced array, and securing this first rivet at a precise location and distance from the axis of the pivot cam;
(f) mounting a second rivet near the pivot cam, this second rivet also having an enlarged midportion of a size like that provided by the first rivet, this second rivet having a length so as to establish and maintain the plate-like members of this other clamp arm in spaced array, and securing this second rivet at a precise location and distance from the axis of the pivot cam, the first and second rivets so positioned that their axes establish a theoretical line therebetween so as to be always parallel to a theoretical line through the pivot axes of the trunnion blocks, said first and second rivets and their precise location at a like distance from the axis of the pivot cam;
(g) mounting another pair of rivets, each having enlarged midportions, one rivet positioned in said first arm assembly adjacent a trunnion block, and another similar rivet positioned in the other arm assembly and also adjacent the trunnion block in said other arm assembly, and (h) forming a hole and fixedly inserting in said hole a stop pin in the enlarged portion of the pivot cam, this stop pin of sufficient length so that said stop pin as it is manipulated comes in way of said first or second rivet, this stop pin being secured so that when the stop pin engages one of the first or second rivets, the cam surfaces formed on the pivot cam engage the apertures in that arm assembly disposed to be actuated by the eccentric cam, the maximum throw of the arm assembly moving the pressure clamp pads closer together and, when the stop pin is moved to the other limit, the clamp pads are moved away from each other.
16. A method of forming and assembling a clamping device as in claim 15 which includes the further step of forming each plate-like member with a substantially identical configuration and apertures and with an upper end providing at the overlaid end an offset, which offset extent is about one-half the thick-ness of the material used in the making of each plate-like member, and also forming the pivot cam with a through hexagonal aperture and forming the smaller diameter end portions of the pivot cam so as to be rotatable in like diameter apertures in the upper extent of each plate-like member.
17. A method of forming and assembling a clamping device as in claim 16 which further includes the step of providing on the trunnion blocks integral pivot pin portions and adjacent these pivot pin portions positioning a rivet between said trunnion block and a pivoted clamp pad.
18. A method of forming and assembling a clamping device as in claim 17 which further includes forming each of the clamp pads of hardened steel with rounded workpiece-gripping pad por-tions and reduced diameter shank portions sized to be retained between the fixed plate-like members, and forming the reduced diameter portions with a transverse hole sized to rotatably retain the central portion of a rivet whose ends are mounted in and pass through holes formed in the end portions of the plate-like arm member portions.
19. A method of forming and assembling a clamping device as in claim 18 in which the limiting means for longitudinal reten-tion of the threaded cap screw further includes providing a screw having a head that is less in diameter than the inner dis-tance of the plate-like members that form the C-shaped arm assemblies, and forming said head with a shoulder terminating with a shank portion sized to be rotatably retained in the smooth bore formed in the trunnion block, the shoulder provid-ing a limiting longitudinal movement control against the outside face of said trunnion, and removably mounting a retainer in a groove formed in the shank of the cap screw, this retainer, when mounted in the groove in the shank, engaging the inner face of the trunnion block.
20. A method of forming and assembling a clamping device as in claim 19 which, also includes forming a groove in the threaded cap screw near the outer end of the threaded portion and mount-ing in this groove a retainer, this retainer providing an outer stop to movement of the threaded trunnion block outwardly along the thread portion of the cap screw.
21. A method of forming and assembling a clamping device as in claim 20 which also includes the step of forming the two eccentric cam surfaces on the pivot cam adjacent the intermedi-ate enlarged portion, and with said cam surfaces of a width substantially the thickness of the metal material providing the plate-like members, and adjacent these eccentric cam portions the pivot cam has outer diameters rotatable in apertures formed in said plate-like members.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000519861A CA1267166A (en) | 1986-10-06 | 1986-10-06 | Clamping device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000519861A CA1267166A (en) | 1986-10-06 | 1986-10-06 | Clamping device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1267166A true CA1267166A (en) | 1990-03-27 |
Family
ID=4134099
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000519861A Expired CA1267166A (en) | 1986-10-06 | 1986-10-06 | Clamping device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1267166A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5601324A (en) * | 1995-06-14 | 1997-02-11 | Purcell; Kenneth S. | Sample container clamp |
-
1986
- 1986-10-06 CA CA000519861A patent/CA1267166A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5601324A (en) * | 1995-06-14 | 1997-02-11 | Purcell; Kenneth S. | Sample container clamp |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |