Winding and tape splicing auxiliary tool for lithium ion battery roll core

Abstract

The utility model discloses a winding and tape splicing auxiliary tool for a lithium ion battery roll core, which belongs to the field of lithium ion battery processing and comprises a bearing plate for bearing a first polar tape and a second polar tape, and a first barrier strip and a second barrier strip are arranged on the side edge of the bearing plate. The first barrier strip is provided with a first abutting face used for abutting against the side edge of the first polar band, the second barrier strip is provided with a second abutting face used for abutting against the side edge of the second polar band, and the first abutting face and the second abutting face are both perpendicular to the upper surface of the bearing plate and located on the same plane. The bearing plate is provided with a plurality of cutting grooves extending in the width direction of the bearing plate, and the multiple cutting grooves are parallel to one another. Scale strips distributed in the length direction of the bearing plate are arranged on the bearing plate, a blade is further arranged on the bearing plate, the first polar band and the second polar band are arranged on the upper surface of the bearing plate in a stacked mode, the blade slides along the cutting groove to cut the first polar band and the second polar band, and therefore the qualified rate of the lithium ion battery roll core can be increased.

Description

Technical Field

[0001] This utility model belongs to the field of lithium-ion battery processing technology, specifically relating to an auxiliary tooling for winding and splicing lithium-ion battery cores. Background Technology

[0002] A power battery is a type of power source that provides power, characterized by high energy, high power, and safety and reliability, and is widely used in power systems and other fields. In the winding process of lithium-ion battery cores, to ensure the continuity of the wound electrode strips, it is usually necessary to perform a splicing operation between adjacent electrode strips.

[0003] Common splicing fixtures typically include a splicing platform, a blade, and adhesive tape. During splicing, two electrode strips are placed on the platform with their ends overlapping, meaning one electrode strip's end is positioned above the other. The blade is then manually used to cut the two electrode strips, removing excess material. Finally, the ends of the two electrode strips are joined together and secured with adhesive tape. This structure allows for the splicing of adjacent electrode strips. However, the cutting position is prone to deviation, leading to variations in the length of the electrode strips at the joint, thus reducing the yield rate of lithium-ion battery cores. Utility Model Content

[0004] To address the aforementioned problems in the prior art, this utility model provides an auxiliary tooling for winding and splicing lithium-ion battery cores. The technical problem to be solved by this utility model is achieved through the following technical solution:

[0005] In a first aspect, this utility model provides an auxiliary tooling for winding and splicing lithium-ion battery cores, including a support plate for carrying a first electrode strip and a second electrode strip. The support plate has a first stop bar and a second stop bar on its side, both extending along the length of the support plate. The first stop bar has a first contact surface for abutting against the side of the first electrode strip, and the second stop bar has a second contact surface for abutting against the side of the second electrode strip. Both the first and second contact surfaces are perpendicular to the upper surface of the support plate and are located on the same plane. The support plate has multiple cutting grooves extending along its width direction, and these grooves are parallel to each other. A cutting gap exists between the first stop bar and the second stop bar, and one end of each cutting groove is located within the cutting gap. The support plate also has scale bars distributed along its length direction, with the scale bars and the first stop bar located on opposite sides of the support plate. A blade is also provided on the support plate. The first electrode strip and the second electrode strip are stacked on the upper surface of the support plate, and the blade slides along the cutting grooves to cut the first electrode strip and the second electrode strip.

[0006] In one embodiment of the present invention, a first inclined surface is provided on the side of the first stop bar facing the second stop bar, and a second inclined surface is provided on the side of the second stop bar facing the first stop bar. A conical hole is formed between the first inclined surface and the second inclined surface, and the opening width at the lower end of the conical hole is smaller than the opening width at the upper end of the conical hole.

[0007] In one embodiment of this utility model, the cutting groove is a right-angled triangular groove, and multiple cutting grooves are spaced apart along the length direction of the bearing plate, and the distance between any two adjacent cutting grooves is equal.

[0008] In one embodiment of this utility model, the support plate is further provided with a frame, which includes a first vertical rod, a second vertical rod, a first horizontal rod, a first longitudinal rod, and a second longitudinal rod;

[0009] The first vertical bar and the second vertical bar are parallel to each other. One end of the first vertical bar is fixedly connected to the bearing plate, and the other end of the first vertical bar is connected to the first horizontal bar. One end of the second vertical bar is fixedly connected to the bearing plate, and the other end of the second vertical bar is connected to the first horizontal bar.

[0010] The first and second longitudinal bars are parallel to each other. One end of the first longitudinal bar is connected to the first horizontal bar, and the other end of the first longitudinal bar is provided with a first clamping member. One end of the second longitudinal bar is connected to the first horizontal bar, and the other end of the second longitudinal bar is provided with a second clamping member. The first clamping member is used to press the first pole strip against the upper surface of the bearing plate, and the second clamping member is used to press the second pole strip against the upper surface of the bearing plate.

[0011] In one embodiment of this utility model, a first threaded hole is provided on the first longitudinal rod, and the first clamping member includes a first bolt. The first bolt is threadedly connected to the first threaded hole, and the first bolt moves toward or away from the first pole band when it is screwed relative to the first threaded hole.

[0012] In one embodiment of this utility model, the second longitudinal rod is provided with a second threaded hole, and the second clamping member includes a second bolt. The second bolt is threadedly connected to the second threaded hole, and the second bolt moves toward or away from the second pole band when it is screwed relative to the second threaded hole.

[0013] In one embodiment of this utility model, both the end of the first bolt and the end of the second bolt are provided with rubber heads.

[0014] In one embodiment of this utility model, a positioning piece is also provided on the first crossbar, and the positioning piece and the first crossbar are slidably connected.

[0015] In one embodiment of the present invention, the positioning piece includes a piece body and a collar. The collar is sleeved on the outer periphery of the first crossbar. One end of the piece body is welded to the collar, and the other end extends vertically. The piece body and the left side surface of the bearing plate are parallel.

[0016] In one embodiment of this utility model, a first screw is also included. A screw hole is provided on the collar, and the first screw is threaded into the screw hole. When the first screw is screwed relative to the screw hole, it moves toward or away from the first crossbar.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0018] In the above-described scheme of this application, the winding and splicing auxiliary tooling includes a support plate for supporting the first and second electrode strips. The support plate has a first stop and a second stop on its side, both extending along the length of the support plate. The first stop has a first contact surface for abutting against the side of the first electrode strip, and the second stop has a second contact surface for abutting against the side of the second electrode strip. Both the first and second contact surfaces are perpendicular to the upper surface of the support plate and are located on the same plane. Thus, by placing the first electrode strip on the support plate and abutting against the first stop, the position of the first electrode strip can be calibrated using the first stop, preventing skewness, and making the installation and positioning of the first electrode strip more convenient and faster. Similarly, by placing the second electrode strip on the support plate and abutting against the second stop, the position of the second electrode strip can be calibrated using the second stop, preventing skewness, and making the installation and positioning of the second electrode strip more convenient and faster. The carrier plate has multiple cutting grooves extending along its width, all parallel to each other. A cutting gap exists between the first and second stop bars, and one end of each cutting groove lies within this gap. The carrier plate also has graduated strips distributed along its length, located on either side of the carrier plate along with the first stop bars. A blade is also provided on the carrier plate. The first and second electrode strips are stacked on the upper surface of the carrier plate. The blade slides along the cutting grooves to cut the first and second electrode strips. With this structure, when the carrier plate has graduated strips distributed along its length, the first and second electrode strips can be placed on the carrier plate using the graduated strips as a reference, improving the accuracy of their placement, reducing deviations when the two electrode strips meet, and increasing the yield rate of lithium-ion battery cores. When the carrier plate has a cutting groove extending along its width, the blade can cut along the cutting groove. The cutting groove limits the blade, which can improve the cutting accuracy. When there are multiple cutting grooves and they are parallel to each other, the blade can switch cutting grooves to improve the accuracy of the cutting position, thereby further reducing the deviation when the two electrode strips are connected and improving the yield of lithium-ion battery cores.

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the auxiliary tooling for winding and splicing tape in an embodiment of this utility model;

[0021] Figure 2 This is a schematic diagram of the first and second pole strips being connected in an embodiment of this utility model;

[0022] Figure 3 This is a front view of the winding and splicing auxiliary tooling in an embodiment of this utility model;

[0023] Figure 4 yes Figure 3 An enlarged view at point A;

[0024] Figure 5 This is a front view of the winding and splicing auxiliary tooling frame in this embodiment of the present invention.

[0025] Figure 6 This is a top view of the frame after the winding and splicing auxiliary tooling is set up in the embodiment of this utility model.

[0026] Reference numerals: 1-Bearing plate, 2-First stop bar, 3-Second stop bar, 4-Cutting groove, 5-Scale bar, 6-Frame body, 7-First vertical bar, 8-Second vertical bar, 9-First horizontal bar, 10-First longitudinal bar, 11-Second longitudinal bar, 12-First clamping component, 13-Second clamping component, 14-Positioning piece, 141-Collar, 142-Piece body, 15-First screw. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0028] Please see Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6This utility model provides an auxiliary tooling for winding and splicing lithium-ion battery cores, including a support plate 1 for supporting a first electrode strip and a second electrode strip. The support plate 1 has a first stop bar 2 and a second stop bar 3 on its side, both extending along the length of the support plate 1. The first stop bar 2 has a first abutment surface for abutting against the side of the first electrode strip, and the second stop bar 3 has a second abutment surface for abutting against the side of the second electrode strip. Both the first and second abutment surfaces are perpendicular to the upper surface of the support plate 1 and located on the same plane. On the plane; the support plate 1 is provided with a cutting groove 4 extending along its width direction, there are multiple cutting grooves 4 and the multiple cutting grooves 4 are parallel to each other, there is a cutting gap between the first stop bar 2 and the second stop bar 3, and one end of the multiple cutting grooves 4 is located in the cutting gap; the support plate 1 is provided with a scale bar 5 distributed along its length direction, the scale bar 5 and the first stop bar 2 are respectively located on both sides of the support plate 1, and the support plate 1 is also provided with a blade, the first pole strip and the second pole strip are stacked on the upper surface of the support plate 1, and the blade slides along the cutting groove 4 to cut the first pole strip and the second pole strip.

[0029] In some embodiments of this application, the support plate 1 is a rectangular plate, which includes an upper surface, a lower surface, a front surface, a rear surface, a left side, and a right side.

[0030] In some embodiments of this application, the first stop bar 2 and the second stop bar 3 are both cuboid structures, and the first abutting surface and the second abutting surface are both vertical surfaces.

[0031] In some embodiments of this application, such as Figure 2 As shown, the first electrode strip has multiple spaced gaps, with the distance between two adjacent gaps being the standard coating length of the electrode sheet. The second electrode strip also has multiple spaced gaps, with the distance between two adjacent gaps being the standard coating length of the electrode sheet. During splicing, the gaps on the first and second electrode strips need to be aligned, then cut along the splicing shear line. Afterwards, excess electrode strip is cleaned and adhesive is applied. Finally, the electrode strips are tightened using a winding machine for subsequent operations.

[0032] Understandably, the coating length of the joint area after the first and second electrode strips are joined usually needs to deviate from the standard coating length of the battery cell by less than or equal to 2mm. However, when the length of the electrode strip at the joint position of the first and second electrode strips is prone to deviation, the coating length of the joint area is prone to be greater than or less than 2mm, resulting in length exceeding the tolerance. When the electrode strip after joining is too long, it can easily cause problems such as scrapping of a single roll of battery core and misalignment of the electrode tabs, thereby increasing the cost of the battery cell and increasing the product defect rate.

[0033] In the above-described scheme of this application, the winding and splicing auxiliary tooling includes a support plate 1 for supporting the first and second electrode strips. The support plate 1 has a first stop bar 2 and a second stop bar 3 on its side, both extending along the length of the support plate 1. The first stop bar 2 has a first contact surface for abutting against the side of the first electrode strip, and the second stop bar 3 has a second contact surface for abutting against the side of the second electrode strip. Both the first and second contact surfaces are perpendicular to the upper surface of the support plate 1 and located on the same plane. Thus, by placing the first electrode strip on the support plate 1 and abutting against the first stop bar 2, the position of the first electrode strip can be calibrated using the first stop bar 2, preventing skewness, and making the installation and positioning of the first electrode strip more convenient and faster. Similarly, by placing the second electrode strip on the support plate 1 and abutting against the second stop bar 3, the position of the second electrode strip can be calibrated using the second stop bar 3, preventing skewness, and making the installation and positioning of the second electrode strip more convenient and faster. The support plate 1 has multiple cutting grooves 4 extending along its width direction, all of which are parallel to each other. A cutting gap exists between the first stop bar 2 and the second stop bar 3, and one end of each cutting groove 4 is located within this gap. The support plate 1 also has graduated strips 5 distributed along its length direction, with the graduated strips 5 and the first stop bar 2 located on opposite sides of the support plate 1. A blade is also provided on the support plate 1. The first electrode strip and the second electrode strip are stacked on the upper surface of the support plate 1. The blade slides along the cutting grooves 4 to cut the first and second electrode strips. With this structure, when the support plate 1 has graduated strips 5 distributed along its length direction, the first and second electrode strips can be placed on the support plate 1 and referenced using the graduated strips 5, improving the accuracy of their placement, reducing deviations when the two electrode strips are joined, and increasing the yield rate of lithium-ion battery cores. When the support plate 1 is provided with a cutting groove 4 extending along its width direction, the blade can cut along the cutting groove 4. The cutting groove 4 is used to limit the blade, which can improve the cutting accuracy. When there are multiple cutting grooves 4 and the multiple cutting grooves 4 are parallel to each other, the blade can switch cutting grooves 4 to improve the accuracy of the cutting position, thereby further reducing the deviation when the two electrode strips are connected and improving the pass rate of lithium-ion battery cores.

[0034] In some embodiments of this application, the first stop bar 2 has a first inclined surface on the side facing the second stop bar 3, and the second stop bar 3 has a second inclined surface on the side facing the first stop bar 2. A conical hole is formed between the first and second inclined surfaces, and the opening width at the lower end of the conical hole is smaller than the opening width at the upper end of the conical hole. With this structure, the blade can extend into or separate from the cutting groove 4 from the conical hole, making the movement of the blade more convenient.

[0035] In some embodiments of this application, such as Figure 3 and Figure 4As shown, the cutting groove 4 is a right-angled triangular groove, and multiple cutting grooves 4 are spaced apart along the length of the support plate 1, with the distance between any two adjacent cutting grooves 4 being equal. This structure makes cutting with the blade more convenient.

[0036] In some embodiments of this application, such as Figure 5 and Figure 6 As shown, the support plate 1 is also provided with a frame 6, which includes a first vertical rod 7, a second vertical rod 8, a first horizontal rod 9, a first longitudinal rod 10, and a second longitudinal rod 11. The first vertical rod 7 and the second vertical rod 8 are parallel to each other. One end of the first vertical rod 7 is fixedly connected to the support plate 1, and the other end of the first vertical rod 7 is connected to the first horizontal rod 9. One end of the second vertical rod 8 is fixedly connected to the support plate 1, and the other end of the second vertical rod 8 is connected to the first horizontal rod 9. The first longitudinal rod 10 and the second longitudinal rod 11 are parallel to each other. One end of the first longitudinal rod 10 is connected to the first horizontal rod 9, and the other end of the first longitudinal rod 10 is provided with a first clamping member 12. One end of the second longitudinal rod 11 is connected to the first horizontal rod 9, and the other end of the second longitudinal rod 11 is provided with a second clamping member 13. The first clamping member 12 is used to press the first electrode band onto the upper surface of the support plate 1, and the second clamping member 13 is used to press the second electrode band onto the upper surface of the support plate 1. With this structure, the first clamping member 12 and the second clamping member 13 are supported by the frame 6. The first clamping member 12 and the second clamping member 13 respectively clamp the first pole belt and the second pole belt, which can improve the stability of the first pole belt and the accuracy of installation and positioning.

[0037] In some embodiments of this application, the first longitudinal rod 10 is provided with a first threaded hole, and the first clamping member 12 includes a first bolt, which is threaded into the first threaded hole. When the first bolt is screwed relative to the first threaded hole, it moves toward or away from the first pole band. With this structure, when the first bolt is screwed relative to the first threaded hole, it moves toward the first pole band, which can press the first pole band onto the bearing plate 1.

[0038] In some embodiments of this application, the second longitudinal rod 11 is provided with a second threaded hole, and the second clamping member 13 includes a second bolt, which is threaded into the second threaded hole. When the second bolt is screwed relative to the second threaded hole, it moves toward or away from the second pole band. With this structure, the second bolt moves toward the second pole band when screwed relative to the second threaded hole, which can press the second pole band onto the support plate 1.

[0039] In some embodiments of this application, both the ends of the first bolt and the second bolt are provided with rubber heads. This structure prevents the first and second electrode bands from being damaged during movement.

[0040] In some embodiments of this application, such as Figure 5 and Figure 6As shown, a positioning piece 14 is also provided on the first crossbar 9, and the positioning piece 14 is slidably connected to the first crossbar 9. With this structure, the positioning piece 14 can slide on the first crossbar 9 to adjust its position, so that the positioning piece 14 corresponds to the gap on the first or second pole band, i.e., it corresponds to... Figure 2 The gap alignment lines correspond to each other, thereby further improving the accuracy of the correspondence between the first and second pole strips. Furthermore, the positioning piece 14 can slide on the first crossbar 9 to adjust its position, so that the positioning piece 14 corresponds to the cutting position on the first or second pole strip, i.e., to... Figure 2 The cutting lines in the middle correspond to the cutting lines, which can further improve the accuracy of cutting the first and second pole strips.

[0041] In some embodiments of this application, such as Figure 5 and Figure 6 As shown, the positioning piece 14 includes a piece body 142 and a collar 141. The collar 141 is sleeved on the outer periphery of the first crossbar 9. One end of the piece body 142 is welded to the collar 141, and the other end extends vertically. The piece body 142 is parallel to the left side surface of the support plate 1. This structure makes the movement of the piece body 142 more convenient, and the mutual restraint between the collar 141 and the first crossbar 9 improves the overall stability of the positioning piece 14.

[0042] In some embodiments of this application, such as Figure 5 and Figure 6 As shown, it also includes a first screw 15, and a screw hole is provided on the collar 141. The first screw 15 is threaded into the screw hole, and the first screw 15 moves toward or away from the first crossbar 9 when screwed relative to the screw hole. With this structure, by moving the first screw 15 toward the first crossbar 9 to press against the surface of the first crossbar 9, the collar 141 can be fixed on the first crossbar 9, thereby improving the stability of the positioning piece 14.

[0043] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0045] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0046] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the protection scope of the present invention.

Claims

1. A winding and splicing auxiliary tooling for lithium-ion battery cores, characterized in that, The device includes a support plate for supporting a first electrode strip and a second electrode strip. The support plate has a first stop bar and a second stop bar on its side. Both the first stop bar and the second stop bar extend along the length direction of the support plate. The first stop bar has a first abutment surface for abutting against the side of the first electrode strip. The second stop bar has a second abutment surface for abutting against the side of the second electrode strip. Both the first abutment surface and the second abutment surface are perpendicular to the upper surface of the support plate and are located on the same plane. The support plate is provided with a cutting groove extending along its width direction. There are multiple cutting grooves and the multiple cutting grooves are parallel to each other. There is a cutting gap between the first stop bar and the second stop bar. One end of each of the multiple cutting grooves is located within the cutting gap. The support plate is provided with scale bars distributed along its length direction. The scale bars and the first stop bar are respectively located on both sides of the support plate. The support plate is also provided with a blade. The first electrode strip and the second electrode strip are stacked on the upper surface of the support plate. The blade slides along the cutting groove to cut the first electrode strip and the second electrode strip.

2. The winding and splicing auxiliary tooling for lithium-ion battery cores according to claim 1, characterized in that, The first stop bar has a first inclined surface on the side facing the second stop bar, and the second stop bar has a second inclined surface on the side facing the first stop bar. A conical hole is formed between the first inclined surface and the second inclined surface, and the opening width at the lower end of the conical hole is smaller than the opening width at the upper end of the conical hole.

3. The winding and splicing auxiliary tooling for lithium-ion battery cores according to claim 1, characterized in that, The cutting groove is a right-angled triangular groove, and multiple cutting grooves are spaced apart along the length direction of the bearing plate, with the spacing between any two adjacent cutting grooves being equal.

4. The winding and splicing auxiliary tooling for lithium-ion battery cores according to claim 1, characterized in that, The support plate is also provided with a frame, which includes a first vertical bar, a second vertical bar, a first horizontal bar, a first longitudinal bar, and a second longitudinal bar; The first vertical bar and the second vertical bar are parallel to each other. One end of the first vertical bar is fixedly connected to the bearing plate, and the other end of the first vertical bar is connected to the first horizontal bar. One end of the second vertical bar is fixedly connected to the bearing plate, and the other end of the second vertical bar is connected to the first horizontal bar. The first longitudinal bar and the second longitudinal bar are parallel to each other. One end of the first longitudinal bar is connected to the first cross bar, and the other end of the first longitudinal bar is provided with a first clamping member. One end of the second longitudinal bar is connected to the first cross bar, and the other end of the second longitudinal bar is provided with a second clamping member. The first clamping member is used to press the first pole strip against the upper surface of the bearing plate, and the second clamping member is used to press the second pole strip against the upper surface of the bearing plate.

5. The winding and splicing auxiliary tooling for lithium-ion battery cores according to claim 4, characterized in that, The first longitudinal rod is provided with a first threaded hole, and the first clamping member includes a first bolt. The first bolt is threadedly connected to the first threaded hole, and when the first bolt is screwed relative to the first threaded hole, it moves toward or away from the first pole band.

6. The winding and splicing auxiliary tooling for lithium-ion battery cores according to claim 5, characterized in that, The second longitudinal rod is provided with a second threaded hole, and the second clamping member includes a second bolt. The second bolt is threaded into the second threaded hole, and when the second bolt is screwed relative to the second threaded hole, it moves toward or away from the second pole band.

7. The winding and splicing auxiliary tooling for lithium-ion battery cores according to claim 6, characterized in that, Both the end of the first bolt and the end of the second bolt are provided with rubber heads.

8. The winding and splicing auxiliary tooling for lithium-ion battery cores according to claim 4, characterized in that, The first crossbar is also provided with a positioning piece, which is slidably connected to the first crossbar.

9. The winding and splicing auxiliary tooling for lithium-ion battery cores according to claim 8, characterized in that, The positioning piece includes a piece body and a collar. The collar is sleeved on the outer periphery of the first crossbar. One end of the piece body is welded to the collar, and the other end extends vertically. The piece body is parallel to the left side surface of the bearing plate.

10. The winding and splicing auxiliary tooling for lithium-ion battery cores according to claim 9, characterized in that, It also includes a first screw, the collar having a screw hole, the first screw being threaded into the screw hole, and the first screw moving toward or away from the first crossbar when screwed relative to the screw hole.

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