WO1993014937A1

WO1993014937A1 - Paper burster and method

Info

Publication number: WO1993014937A1
Application number: PCT/US1993/000580
Authority: WO
Inventors: William J. Lund; Thomas Devlin
Original assignee: Curtis Manufacturing Company, Inc.; Lund Company, Ltd.
Priority date: 1992-02-03
Filing date: 1993-01-22
Publication date: 1993-08-05

Abstract

A bursting apparatus and method are disclosed for separating a multisheet perforated continuous paper form into individual sheets. The apparatus is particularly suitable for multisheet perforated continuous paper form configured so that characters imprinted on a top sheet thereof are copied to underlying sheets by imprinting forces. The apparatus includes a conveying system (22, 24) for moving the perforated continuous paper form to a bursting station (26) and for conveying separated sheets from the bursting station to a receiving station. A compression-enhanced clamp (106, 108), disposed at said bursting station, is provided for engaging the continuous paper form with impact forces insufficient to cause copy formation on underlying sheets and a bursting bar (186) is provided for rupturing the continuous paper sheets along a perforation when the continuous paper sheet is engaged by the spring-enhanced clamp means.

Description

PAPER BURSTER AND METHOD

BACKGROUND OF THE INVENTION

The present invention generally relates to the separation of continuous perforated forms into indi¬ vidual sheets, the process being known in the art as bursting.

Forms suitable for bursting in accordance with the present invention are single and multisheet forms which include a sheet of perforations for the lengths of individual sheets and edge perforations with paper tractor feedholes therein for enabling movement of the forms through a printer or the like.

As set forth in U.S. Patent No. 5,120,144, most high-speed computer printers utilize forms having paper-drive edge tear strips with punched holes therein which are engaged for moving the paper form in a coordinated manner past a printing station, or print head. In many instances, the paper form consists of a single sheet; however, it is not uncommon for the form to include multiple sheets with a transfer system therebetween for making simultaneous copies. Often, printers are used in retail establishments for simul¬ taneously producing sales receipts, store records copies, and inventory control documents.

In order to produce usable individual sheets and copies thereof, it is necessary to manually separate, or burst, the continuous forms along the sheet per¬ forations therein and separate the paper-drive edge tear strips to produce conventional office size documents. Known bursting devices operate on one or two principles. In each of the bursting methods, the continuous form is clamped and, in accordance with one principle of operation, a bursting bar is used to impact the sheet perforations in order to separate, or burst, the sheets, and, in accordance with the second principle, the sheets may be separated by pulling or stressing the continuous form along the sheet perfora¬ tions.

All such devices have been characteristically large, expensive, noisy and undependable. Conse¬ quently, such apparatus required supervision to insure reliable operation.

Thus, it is not surprising that while many devices have been developed and patented over the years, no product is currently available, at consumer price levels, which can reliably serve the bursting needs attendant to the plethora of printers now being produced for the consumer market.

Most prior art bursting devices have not become popular for home and office use because of a number of problems. These problems include bending, wrinkling, irregular bursting, or unwanted ripping of sheets.

Importantly, in the case of multiple sheet continuous forms, characters imprinted on the top sheet thereof are copied to underlying sheets by imprinting forces. Therefore, clamping of the contin¬ uous form to facilitate bursting as hereinabove described may cause smudging or imprinting of underly¬ ing sheets with outlines of the clamping devices or may cause blotting or obscuring of characters, thereby limiting, or eliminating, the usefulness of such copies.

Heretofore, bursters have utilized clamping members molded from elastomer or the like which are for able under pressure in order to clamp continuous forms for bursting. This design is utilized in order that slippage of the continuous form during bursting by separate bursting bar is minimized and further to prevent the transfer of impact forces to underlying sheets, as hereinabove described.

Unfortunately, as with most resilient members, such clamping devices tend to harden over time due to both use and aging of the material. Consequently, long term dependability of such devices is not achiev¬ able and this design necessitates replacement of such members which is both inconvenient and costly.

The present invention satisfies the need for a dependable, efficient, low cost bursting device which is capable of not only separating multisheet forms into individual sheets without smudging the underlying copies but also may be utilized to separate paper- drive edge tear strips from the paper form in a single stage operation.

SUMMARY OF THE INVENTION

Apparatus in accordance with the present inven¬ tion for bursting a multisheet perforated continuous paper form into separated sheets generally includes means for conveying the multisheet perforated continu-: ous paper form to a bursting station, means for conveying separated sheets from the bursting station to a receiving station, and compression-enhanced clamp eans disposed at the bursting station for engaging the continuous paper form with impact forces insufficient to cause copy formation on underlying sheets.

This is particularly important for multisheet forms which are configured so that characters which are imprinted on a top sheet thereof are copied to underlying sheets by impact forces. The compression- enhanced clamp means may include spring means for causing, in concert with end plates attached thereto, movable clamp bars to abut stationary clamp bars with a relatively constant pressure over a period of time. No deformable resilient element is utilized in the present invention and therefore, long term use without deterioration of performance is ensured.

Bursting means are provided for rupturing the continuous paper sheet along a perforation when the continuous paper sheet is engaged by the compression- enhanced clamp means, and drive means is provided for coordinating engagement of the compression-enhanced clamp means with the continuous paper form and the bursting means.

More particularly, the compression-enhanced clamp means may include a pair of spaced apart stationary clamp bars disposed at the bursting station above a path of the continuous paper form entering the bursting station and a pair of spaced apart movable clamp bars disposed at the bursting station below the continuous paper form path. The end plate means are slidably attached ends of the movable clamp bars and fixedly attached to the spring means, which may be a leaf-type spring► Because the movable bars are not fixedly attached to the end plate means but are supported by the leaf spring, abrupt impact forces are effectively smoothed into a constant force loading engagement which effectively prevents the marking of underlying copies of the continuous form. This also enables the use of rigid stationary and movable clamp bars without smudging of underlying copies.

The bursting means may include a rod disposed between the pair of spaced apart movable clamp bars and means are provided for propagating rupture of the continuous form by the rod by mounting and supporting the rod at an angle of about 1.5 degrees to the plane of the continuous paper form when the paper form is clamped between the stationary and movable-clamp bars.

The drive means hereinabove recited includes a cam follower attached to the end plate means and cam means disposed at an operative relationship with the cam follower for translating rotational movement of the cam means into translational movement of the end plate means in order to move the movable clamp bars and spring means. The combination of the spring and the movable clamp bars, which are slidably attached to the end plates, eliminates critical tolerances in this cam arrangement.

That is, because movement of the movable clamp bars is backed up and supported by the spring, which can support and move the clamp bars within the slidable end plates, close tolerances on the cam and cam follower are eliminated. Naturally, wearing of the cam and cam follower similarly have little effect on the cushioned clamping characteristics of the apparatus of the present invention. The bursting bar means includes a rod and means for supporting a rod, which include a pair of upright members and means attaching the upright members to the cam means in a noncoaxial relationship for causing coordinated translational movement of the rod.

In one embodiment of the present invention, paper tractor feed separator means are provided for both separating the paper drive edge tear strips from the continuous paper form along the edge perforations and for conveying the multisheet continuous paper form to a burster station.

More particularly, the tractor feed separator includes a frame, frame shoulder means for guiding the edge tear strip to enable a body portion of the paper form to be urged out of the plane of the edged tear strip along the edge perforations in.order to separate the body portion from the edge tear strip. In addi- tion, a lid is provided with a shoulder means for urging the body portion out of the plane of the edged tear strip to separate the body portion from the edged tear strip. In this embodiment, means are also provided for guiding the separated paper drive edge tear strips away from the bursting station.

A method in accordance with the present invention includes the steps of conveying a single or multisheet perforated continuous paper form to a bursting station and conveying separated sheets from the bursting station to a receiving station. During this conveyance the continuous paper form is engaged by compression- enhanced clamps with impact forces insufficient to cause copy formation on any underlying sheets. In addition the continuous paper sheets are ruptured along a perforation when the continuous paper sheet is engaged by the compression-enhanced clamps. These steps are coordinated in order that the bursting occurs during the clamping of the continuous paper sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will be better understood by the following description when considered in conjunction with the accompanying drawings in which:

Figure l is a perspective view of apparatus for bursting a multisheet perforated continuous paper form in accordance with the present invention showing intake of the form;

Figure 2 is a perspective view of the apparatus in accordance with the present invention showing a receiving station for individually separated sheets and separate disposal of edge tear strips;

Figure 3 is an exploded view of the mechanism of the present invention;

Figure 4 is a cross-sectional view of the paper tractor feed separator of the present invention showing a lid held in an open position, in phantom lines, and in a closed position, in solid lines;

Figure 5 is a side view of the apparatus of the present invention taken along the line 4-4 of Figure 1; Figure 6 is a front view of the apparatus without a cover;

Figure 7 is a top view of the present invention. showing paper tractor feed separators in accordance with the present invention; and Figure 8 is a detailed, exploded perspective view of portions of a side plate, a cam follower, leaf spring, and movable clamp bars showing attachment thereof to one another in accordance with the present invention.

DETAILED DESCRIPTION

Turning now to Figures l and 2, there is shown, in perspective, apparatus 10 in accordance with the present invention, for bursting a multisheet per¬ forated continuous paper form 12 into separated sheets 14.

As hereinbefore noted, the apparatus 10 is particularly suitable for bursting a multisheet perforated continuous paper form 12 which is config¬ ured so that the characters imprinted on the top sheet thereof are copied to underlying sheets by imprinting forces. Such forms are typical of those used in modern offices, and the forms either utilize separate carbon transfer paper between sheets or the sheets are chemically treated for the transfer of imprinted characters to underlying sheets.

As shown in Figures 1 and 2, the apparatus 10 may include any suitable housing 18 which may be sized for placement adjacent to a printer (not shown) for accepting printed forms 12 therefrom or incorporated into a printing device (not shown) in a conventional manner so that the printing device and apparatus 10 form a single unit (not shown) . The following de¬ scription of the apparatus 10 is limited to a self- standing unit as shown in Figures 1 and 2; however, it is to be appreciated that the described mechanical features of the present invention are equally suitable for incorporation into a self-standing printer/burster device (not shown) . As shown in Figure 3, a pair of tractor feed separators 22 24 provides a means for conveying the multisheet perforated continuous paper form 12 to a bursting station.

The paper tractor feed separators 22 24 are specifically described in U.S. Patent No. 4,940,347 and in U. S. Patent Application Serial No. 07/516,551, now U.S. Patent No. 5,120,144, these references being incorporated herewith by specific reference thereto.

The two paper feed separators are mirror images of one another and slidably mounted on rods 28 30 in a conventional manner for providing a means for enabling the engagement of the two tractor feed separators 2224 with continuous paper forms 12 having different widths.

Turning to Figure 4, which is a cross-section of the paper tractor feed separator 22, each of the paper tractor feed separators include a frame 34, a belt 36 for moving drive pins 38 along the frame 34, and a drive sprocket 40 (see Figure 3) for moving the belt 36 and the drive pins 38.

As hereinbefore described, the separators 22 24 may be disposed on a pair of parallel rods 28, 30 with the rod 28 being power driven and engaging the sprocket 40 for driving the belt 36 and drive pins 38 for moving the paper form 12 towards the bursting station 26. A lid 42 may be hinge 46 mounted to the frame 34 and held in either an open or a closed position by a spring 48, coupled to the lid 42 by means of a pin 50 and aligned with the hinge 46 and a frame pin 52 so that an off-set relationship there- between enables the spring 48 to hold the lid 42 in either a closed position, shown in solid line in Figure 4, or in an open position, shown in phantom line in Figure 4. The open position facilitates the initial feeding of the paper form 12 into the tractors 22, 24 and the coupling of paper strip holes 56 with the drive pins 38.

Returning to Figure 3, it can be seen that the rod 28 may be connected to a pulley arrangement 60 by means of a hub 66, which is interconnected with a drive hub 62 by means of a belt 68, with the drive hub 66 being powered by a motor 70 through a drive shaft 72 with the rotational speed of the rod 28 being determined by the diameters of the hubs 62, 66 and drive wheels 76, 78, the latter being mounted on the drive shaft 72 of the motor 70. The belt 68 also passes over drive wheels 80 interconnected respec¬ tively to rollers 84, and followers 86 by rods 88, 90, respectively, in order to provide a means for conveying separated sheets 14 to a tray, or receiving station, 94 conventionally attached to a rear 96 of the housing 18, as shown in Figure 2. The tray 94 may include a plurality of slots 100 for enabling the adjustment of upright members 102 for accommodating paper of different sizes.

As shown in Figures 3 and 5-7, disposed at the bursting station 26 are a pair of spaced apart sta- tionary clamp bars 106108 positioned above a path 110 of the continuous paper form 12. The stationary clamp bars 106 108 may be formed from any suitable solid material and fixedly attached to either a frame (not shown) or the housing 18 by ends 112, 114, 116, 118 of the stationary clamp bars 106, 108. Disposed below the paper path 110 are a pair of movable clamp bars 122, 124 supported and moved by end plates 130, 132 and leaf spring 134, as hereinafter described in greater detail. The leaf spring 134 provides compression enhancement of the oveable clamp bars 122, 124. The movable clamp bars 106108 are formed from a solid material such as a metal or hard plastic.

It should be appreciated that the clamping force is provided by the spring 134 and not the elastic coating, which may be, for example, only about 0.062 inches thick. Hence resilient members are not required in the apparatus 10 of the present invention. The timed, or programmed, engagement of the movable clamp bars 122, 124 and the stationary clamp bars 106, 108 provides clamping of the multipage form 12 without smudging of underlying pages due to transfer of impact forces thereto during the clamping operation, despite the use of rigid clamp bars.

Turning now to Figure 8, which shows exploded view portions of the end plate 130, clamp bars 122, 124, leaf spring 134 and side plate 138. As hereinafter described, the end plate 130 is attached to a cam follower 152 and is slidably mounted to the side plate 138 by way of angle members 142, 144, which engage cutaway portions 146, 148 respectively of the end plate 130, enabling sliding motion therein, as the end plate 130 is moved upwardly and downwardly by the cam follower 152.

The movable clamp bars 122, 124 include ends 156, 158 with outwardly projecting keys 162, 164 respec- tively, for sliding engagement with slots 168, 170, disposed in the end plate 130. The leaf spring 134 is secured by a tab 174 into a slot 176 in the end plate 130.

In operation, when the movable clamp bars 122, 124 are in a spaced apart position with respect to the stationary clamp bars 106, 108 for allowing the paper to pass therebetween, the spring urges the movable clamp bars 122, 124 to a maximum upward position with respect to the end plate in which the keys 162, 164 are positioned against the tops 178, 180.

As the end plate is moved upwardly by the cam mechanism, as hereinafter described, the movable clamp bars 122, 124 are moved into an abutting relationship with the stationary clamp bars 106, 108 with the continuous paper form therebetween. Because the movable clamp bars 122, 124 are movable within the slots 168, 170, the pressure between the stationary clamp bars 106, 108 and movable clamp bars 122, 124 is controlled by the spring 134. With proper selection of the spring 134, slot sizes 168, 170, keys 162, 164, the impact forces may be controlled so that copy formation of underlying sheets does not occur.

That is, the pressure therebetween may be kept at a relatively constant value over a period of time. Naturally, the spring 134 size, thickness and material configuration, as well as the slot 168, 170 size, and key 164, 162 dimensions, are all empirically deter- mined and dependent upon the drive configurations, hereinafter described in greater detail, all of these being within the realm of state of the art engineering determination and evaluation.

Actual bursting of the paper form 12 is done by a bursting bar 186, which is disposed between the ovable clamp bars 122, 124 and moved upwardly and against sheeted perforations 188 in the continuous form 12. The bursting bar 186 is supported at ends 190, 192 by upright members 198, 200 interconnected with cams 202, 204 as hereinafter described.

In order to provide a means for propagating the rupture of the continuous paper form 12 along the perforations 188, the upright members 198 and 200 are positioned and sized for supporting and moving the bursting bar 186 at an angle A of about 1.5° to the plane of the continuous paper form 12 when the.form 12 is clamped between the stationary clamp bars 106, 108 and movable clamp bars 122, 124.

This arrangement enables initial contact of the bursting bar 186, along a small portion of the per¬ forations 186, thereby providing a greater force per square inch to initiate rupture of the paper form 12. Once the initial rupture has occurred, continued movement of the bursting bar 186 in an upward direc¬ tion causes complete separation of the continuous paper form 12 into separate sheets 114.

Shaft 210 driven cams 202, 204, in combination with a drive gear 212, 214 and a motor 216, provide a means for coordinating engagement of the spring 134 enhanced movable clamp bars 122, 124 with the continu¬ ous paper form 12 and bursting bar 186.

Rotation of the cams 202, 204 by the shaft 210 enables the cam followers 152, 154 to translate such rotational movement into translational movement of the end plates 130, 132 in order to move the movable clamp bars 122, 124 and spring 134 for clamping the continu¬ ous paper form 12. The exact translation of movement is dictated by offset surfaces 220, 222 on the cams 202 and 204 respectively. The sizing of the cam followers 152, 154, the cams 202, 204, and the sur¬ faces 220, 222 may be determined in a manner enabling proper movement of the end plates 130, 132 to ensure engagement of the movable bars 122, 124 against the stationary clamp bars 106, 108 with the paper form therebetween.

It should be appreciated that because of the compliance of the spring 134, the cams 202, 204, cam followers 152, 154, and particularly the offset surfaces 220, 222 need not be manufactured with close tolerances since any variations therein are easily accommodated by the compliance of the spring 134.

Naturally, this also results in long term reliability of the burster 10 since wear on the cams 202, 204, cam followers 152, 154, and offset surfaces 220, 222 will not seriously affect the engagement of the movable clamp bars 122, 124 or the pressure exerted on the continuous form. Consequently, the acceptability of large tolerances on the cams 202, 204, cam followers 152, 154, and offset surfaces 220, 222 result in manufacturing procedures which significantly lower the cost of manufacture of the apparatus.

The upright members 198, 200 attached to the cams 202, 204 respectively by pins 226, 228 provide a means for attaching the upright members 198, 200 to the cams 202, 204 respectively in a noncoaxial rela¬ tionship for causing coordinated translational move¬ ment of the bursting rod 186. Placement of the pin in a specific angular relationship with the offset surfaces 220, 224 enables this eccentric drive configuration to raise the bursting bars into contact with the continuous form 12 so that the bursting bars strike the continuous paper sheet 12 when the continuous paper sheet 12 is clamped between the movable and stationary clamp bars 122, 124, 106, 108.

Power may be supplied to the paper drive motor 70 and the bursting motor 216 when a sensor 230 indicates the leading edge of a paper form 12 conveyed to the bursting station 26 by the tractor drives 22, 24. The sensor 230 also serves to stop the paper drive motor 70 and bursting motor 216 when the sensor 230 detects a trailing edge of the continuous paper form 12. Any suitable circuit board may be employed to coordinate the sensing of the continuous form leading edge in order to provide power to the drive motor 170 and bursting motor 216.

Continuous forms 12 having different size individual sheets 14 as defined by the perforations 166 may be accommodated by the controlling of the paper drive motor with respect to the bursting motor to provide a coordination so that the bursting bar 186 will strike the perforations 188 despite the length of the individual sheets. This control configuration is well within the state of the art known to one so skilled.

In operation, the edge tear strips 234, 236, defined by edge perforations 238, 240 are removed prior to bursting. As described in U.S. Patent No. 4,940,347 and U.S. Patent Application Serial No.

07/516,551, now U.S. Patent No. 5,120,144, frame shoulders 244 of the tractors 22, 24 provide a means for guiding the edge tear strips 234, 236 to enable a body portion 250 to be urged out of the plane of the edge tear strips 234, 236 in order to separate the body portion 250 from the edge tear strips 234, 236. The lid 42 accordingly includes shoulder 252 means for urging the body portion out of the plane of the edge tear strips 234, 236 in order to separate the body portion. As shown in Figure 2, the edge tear strips 234, 236 may be guided around the bursting station 26 and below the receiving station 94 for separate collection and disposal thereof.

Although there has been hereinabove described a PAPER BURSTER in accordance with the present inven¬ tion, for the purpose of illustrating the manner in which the invention may be used to advantage, it should be appreciated that the invention is not limited thereto. Accordingly, any and all modifica- tions, variations, or equivalent arrangements which may occur to those skilled in the art, should be considered to be within the scope of the present invention as defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. Apparatus for bursting a multisheet per¬ forated continuous paper form into separated sheets, said multisheet perforated continuous paper form being configured so that characters imprinted on a top sheet thereof are copied to underlying sheets by imprinting forces, said apparatus comprising:

means for conveying said multisheet perforated continuous paper form to a bursting station; means for conveying separated sheets from said bursting station to a receiving station; compression-enhanced clamp means, including rigid clamp bars, disposed at said bursting station, for engaging the continuous paper form with impact forces insufficient to cause copy formation on underlying sheets; bursting means for rupturing the continuous paper sheets along a perforation when the continuous paper sheet is engaged by the spring- enhanced clamp means; and drive means for coordinating engagement of said compression-enhanced clamp means with the continuous paper form and the bursting means.

2. The apparatus according to claim 1 wherein said compression-enhanced clamp means comprises:

a pair of spaced apart stationary rigid clamp bars disposed at said bursting station above a path of said continuous paper form enter¬ ing the bursting station; a pair of spaced apart movable rigid clamp bars disposed at said bursting station below the continuous paper form; means for moving the movable clamp bars into an abutting relationship with the stationary clamp bars in order to clamp the continuous paper form therebetween; and spring means, disposed against the movable clamp bars, for causing, in concert with said means for moving the movable clamp bars, said movable clamp bars to abut the stationary clamp bars with a relatively constant pressure over a period of time.

3. The apparatus according to claim 2 wherein the means for moving the movable bars comprises end plate means slidably attached to ends of the movable clamp bars and fixedly attached to said spring means.

4. The apparatus according to claim 3 wherein said spring means comprises a leaf-type spring.

5. The apparatus according to claim 4 wherein said bursting means comprises a rod disposed between the pair of spaced apart movable clamp bars.

6. The apparatus according to claim 5 further comprising means for propagating rupture of the continuous paper form by the rod.

7. Apparatus for bursting a multisheet perforated continuous paper form into separated sheets, said multisheet perforated continuous paper form being configured so that characters imprinted on a top sheet thereof are copied to underlying sheets by imprinting forces, said apparatus comprising: means for conveying said multisheet perforated continuous paper form to a bursting station; means for conveying separated sheets from said bursting station to a receiving station; compression-enhanced clamp means, disposed at said bursting station, for engaging the continuous paper form with impact forces insufficient to cause copy formation on underlying sheets; bursting means for rupturing the continuous paper sheets along a perforation when the continuous paper sheet is engaged by the spring- enhanced clamp means, said bursting means comprising a rod disposed between the pair of spaced apart movable clamp bars and means for propagating rupture of the continuous paper form comprising means for supporting and moving the rod at an angle of about 1.5 degrees to a plane of the continuous paper form when same is clamped between the stationary and movable clamp bars; and drive means for coordinating engagement of said compression-enhanced clamp means with the continuous paper form and the bursting means.

8. The apparatus according to claim 7 wherein said drive means comprises a cam follower attached to the end plate means and cam means, disposed in an operative relationship with said cam follower, for translating rotational movement of said cam means into translational movement of the end plate means in order to move the movable clamp bars and spring means.

9. The apparatus according to claim 8 wherein the means for supporting the rod comprises a pair of upright members and means, attaching said upright members to said cam means in a non-coaxial relation- ship, for causing coordinated translational movement of the rod.

10. Apparatus for bursting a perforated continu¬ ous paper sheet into separated sheets, said apparatus comprising:

means for conveying the continuous paper sheet to a bursting station; means for conveying separated sheets from said bursting station to a receiving station; a pair of spaced apart stationary, rigid clamp bars disposed at said bursting station above a path of said continuous paper sheets entering the bursting station; a pair of spaced apart movable rigid clamp bars disposed at said bursting station below the continuous paper sheet path; end plate means, slidably attached to ends of said pair of spaced apart movable clamp bars, for moving the movable clamp bars into an abutting relationship with said pair of spaced apart stationary clamp bars in order to clamp the continuous paper sheet therebetween; compression means, fixed to said end plate means and disposed below the movable clamp bars, for causing, in concert with said end plate means, said movable clamp bars to abut the stationary clamp bars with a relatively constant pressure over a period of time; bursting bar means, disposed between the movable clamp bars, for rupturing the continuous paper sheet along a perforation when the continuous paper sheet is clamped between the movable and stationary clamp bars; and drive means for coordinating movement of the movable clamp bars, spring means and the bursting bar means in order that the bursting bar means strikes the continuous paper sheet when the continuous paper sheet is clamped between the movable and stationary clamp bars.