Work tool assembly with tip adapter and anti-bending stabilizer therefor

Abstract

A work tool assembly (22) includes a work tool lip (26) and a plurality of tip adapters (50) coupled to the work tool lip, and each of the plurality of tip adapters includes an upper adapter leg (58), a lower adapter leg (60), and a mounting slot (56) receiving a forward lip edge (34). Each of the upper and lower adapter legs includes a first constraining flange (80) and a second constraining flange (82). The work tool assembly also includes anti-bend stabilizers (88) welded to the work tool lip and each including a hold-down head (98) in contact with one of the first constraining flange or the second constraining flange. The anti-bending stabilizer limits bending of the tip adapter by reacting to a bending load on a tooth tip (28) of the work tool lip.

Description

Technical Field

[0001] This disclosure relates generally to a work tool assembly, and more specifically to limiting the bending of the work tool tip adapter by means of a bend-resistant stabilizer. Background Technology

[0002] Many different types of work tools are used in combination with machinery in a wide range of operational environments, from construction, forestry, and landfills to material handling and mining. In many applications, work tools and related components may be subjected to extremely harsh conditions, resulting in shocks, wear, and various types of loads. For certain operational environments, engineers have developed a variety of replaceable components for work tools, such as guards, edges, and teeth or tooth tips. Such replaceable components can be periodically replaced with new parts without replacing or repairing larger or hard-to-access parts in the machinery. Parts of work tool assemblies may also be desirable for temporary removal to repair the assembly (e.g., by removing encapsulated material). Therefore, significant R&D resources are invested in extending the lifespan of work tools, optimizing performance, and reducing the workload of replacing or repairing work tool parts when necessary. An example of a work tool for mining machinery applications is described in U.S. Patent No. 9,127,435 B2 by Bienfang et al. Summary of the Invention

[0003] In one aspect, a tooling assembly includes a tooling lip and a plurality of tip adapters. The tooling lip has an upper lip surface and a lower lip surface, each extending rearward from a forward lip edge. The plurality of lip adapters are laterally arranged along the forward lip edge and each includes a front adapter end, a rear adapter end, and a mounting groove that receives the forward lip edge and extends forward from the rear adapter end. Each mounting groove is defined between an upper adapter leg that contacts the upper lip surface and a lower adapter leg that contacts the lower lip surface. At least one of the upper and lower adapter legs in each tip adapter includes a first constraint flange and a second constraint flange on its opposite sides, respectively. The work tool assembly also includes multiple anti-bend stabilizers, each having a base and a clamping head. The base is attached to the work tool lip at a position on the side of one of the multiple tip adapters. The clamping head extends outward from the base and contacts one of the first constraint flanges or the second constraint flanges of a corresponding tip adapter.

[0004] On the other hand, a tip adapter for a working tool includes an adapter body having a front adapter end with a tip mounting seat, a rear adapter end, and a mounting groove defined between an upper adapter leg and a lower adapter leg for receiving a forward lip edge of a working tool lip, and extending forward from the rear adapter end. At least one of the upper adapter leg and the lower adapter leg includes a first constraint flange and a second constraint flange on their opposing sides, respectively. The first constraint flange and the second constraint flange each include a side-facing contact surface, a base contact surface, and a rear-facing contact surface, the side-facing contact surface, the base contact surface, and the rear-facing contact surface collectively forming a cutout in the respective upper adapter leg or the lower adapter leg.

[0005] In another aspect, a bend-resistant stabilizer for a work tool includes a stabilizer body comprising a base having a downwardly facing welded surface and a peripheral welded surface, the downwardly facing welded surface defining a footprint area at least partially curved, and the peripheral welded surface adjacent to and extending upwardly and outwardly from the downwardly facing welded surface. The stabilizer body also includes a neck and a clamping head extending outwardly from the neck and having a plurality of contact surfaces thereon. The plurality of contact surfaces include: an end face surface facing outwardly from the base, a first proximal end face surface, a second proximal end face surface, and a proximal end lower face surface. Attached Figure Description

[0006] Figure 1 This is a schematic view of a machine according to one embodiment;

[0007] Figure 2 This is a schematic view of a work tool component according to one embodiment;

[0008] Figure 3 This is a schematic view of a portion of a work tool component according to one embodiment;

[0009] Figure 4 This is another illustrated view of a part of a work tool component according to one embodiment;

[0010] Figure 5 This is a cross-sectional view of a portion of a work tool assembly according to one embodiment;

[0011] Figure 6 This is a side view of a tip adapter according to one embodiment;

[0012] Figure 7 This is a perspective view of a tip adapter according to one embodiment;

[0013] Figure 8This is a perspective view of an anti-bend stabilizer according to one embodiment;

[0014] Figure 9 This is another perspective view of an anti-bend stabilizer according to one embodiment;

[0015] Figure 10 This is a top view of an anti-bend stabilizer according to one embodiment;

[0016] Figure 11 This is a front view of an anti-bend stabilizer according to one embodiment; and

[0017] Figure 12 This is a side view of an anti-bend stabilizer according to one embodiment. Detailed Implementation

[0018] refer to Figure 1 A machine 10 according to one embodiment is shown. The machine 10 is shown in the context of a mining machine and has a frame 12 supported on a ground-engaged track system 14. The machine 10 also includes an implement system 16 having a boom 18, a stick or handle 20 pivotally supported by the boom 18, and a bucket or digging bucket 24 coupled to the stick 20. Those skilled in the art will... Figure 1 The mining machine illustrated is identified as a bucket excavator. Various other mining machines (such as front shovel excavators), as well as other types of off-highway machinery (such as tractors or loaders), are entirely within the scope of this disclosure. For example, implement system 16 can be operated to capture, hoist, and dump materials at the working face of a mine.

[0019] Bucket 24 is part of tooling assembly 22 and may include tooling lip 26, which is a separate part or assembly that can be attached to the main bucket body. Figure 3 Multiple tooth tips 28 supported on the working tool lip 26 can also be seen. During use, the tooth tips 28 may need to be replaced due to wear, damage, etc. The associated support structure for the tooth tips 28 may also be replaced or repaired periodically. It has been observed, for example, that certain types of bending loads on the support structure of the tooth tips 28 may cause premature performance degradation or failure of the working tool assembly 22. As will become further apparent from the following description, solutions and improvements related to these and other objectives are contemplated in this disclosure.

[0020] Still referencing Figures 2 to 5The tool lip 26 includes an upper lip surface 30 and a lower lip surface 32, each extending rearward from a forward lip edge 34. A plurality of forward tooth tips 28 are each mounted to a corresponding tip adapter of a plurality of tip adapters 50 arranged laterally along the forward lip edge 34 of the tool lip 26. A plurality of retractable tooth tips 36 are arranged laterally along the forward lip edge 34 and alternate with the plurality of tip adapters 50. The retractable tooth tips 36 may be retracted relative to the forward tooth tips 28. The retractable tooth tips 36 may be positioned on the tip adapters, or may be directly attached to the tool lip 26, or may be omitted from the design in some embodiments. As indicated above, the tool assembly 22 may include a bucket 24. Other embodiments may include a blade or another type of tool. Therefore, the tool lip 26 may include a bucket lip and includes a first upturned outer lip edge 38 and a second upturned outer lip edge 40. Each of the upper lip surface 30 and the lower lip surface 32 may extend laterally between the first upturned outer lip edge 38 and the second upturned outer lip edge 40.

[0021] In this specification, "lateral" or "sideways" means a direction toward one of the outer lip edges 38 and 40. A forward direction generally means toward or away from the front lip edge 34. A backward or rearward direction has a "relative" meaning. A front-to-back direction generally means from front to back. Tip adapters 50 are arranged laterally along the front lip edge 34 and each includes an adapter body 51. The adapter body 51 (sometimes used interchangeably with the tip adapter 50) may be a one-piece metal casting in some embodiments. Each of the plurality of tip adapters 50, sometimes referred to in the singular hereinafter, may be identical to each other and each includes a front adapter end 52, a rear adapter end 54, and a mounting groove 56 that receives the front lip edge 34 and extends forward from the rear adapter end 54.

[0022] Each mounting slot 56 is defined between an upper adapter leg 58 that contacts the upper lip surface 30 and a lower adapter leg 60 that contacts the lower lip surface 32. The tip adapter 50 may include a tooth tip mount 62 on the front adapter end 52, the tooth tip mount being shaped to couple into a gap or recess in one of the tooth tips 28. Attachment and locking structures, including, for example, a tooth tip engaging boss 69, may be located on the front adapter end 62 and project generally forward from it. It may also be noted from the figures that the front adapter end 62 may have a taper that narrows in a generally forward direction, although this disclosure is not limited thereto.

[0023] The tooling assembly 22 may also include a plurality of wedge-shaped components 70 that releasably secure the tip adapter 50 to the tooling lip 26. In an embodiment, the wedge-shaped components 70 may pass through the tip adapter 50 to attach to the tooling lip 26. The wedge-shaped components 70 may employ a known design. Also according to a known design, the tooling assembly 22 may further include a plurality of gaskets 72 and a plurality of static beams 73 coupled between the adapter 50 and the tooling lip 26. The tip adapter 50 may further include a lifting ring 74.

[0024] The tip adapter 50 also includes a top surface 64 partially formed in the upper adapter leg 58 and an upper inner surface 66 formed on the upper adapter leg 58. The tip adapter 50 also includes a bottom surface 68 and a lower inner surface 67 formed on the lower adapter leg 60. A mounting groove 56 is defined between the upper inner surface 66 and the lower inner surface 67.

[0025] Still referencing Figure 6 and Figure 7 At least one of the upper adapter leg 58 and lower adapter leg 60 in each tip adapter 50 includes a first constraint flange 80 and a second constraint flange 82 on its opposite sides 76 and 78. In an embodiment, the upper adapter leg 58 includes the first constraint flange 80 and the second constraint flange 82, and the lower adapter leg 60 includes a third constraint flange 84 and a fourth constraint flange 86. Therefore, embodiments in which only one of the upper adapter leg 58 and the lower adapter leg 60 includes a constraint flange are contemplated. The description and discussion of any constraint flange herein can be understood by analogy to refer to any other constraint flange. In practical implementation, both the upper adapter leg 58 and the lower adapter leg 60 are equipped with constraint flanges, and their structure is designed to receive anti-bending hardware to limit the bending of the tip adapter 50 relative to the tool lip 26, as further discussed herein.

[0026] For this purpose, the working tool assembly 22 also includes a plurality of anti-bend stabilizers 88, each having a base 96 attached to the working tool lip 26, such as by welding to the side of one of the tip adapters 50. Each of the plurality of anti-bend stabilizers 88 (sometimes referred to in the singular hereinafter) includes a clamping head 98 extending outward from the base 96 and contacting a first constraint flange 80 or a second constraint edge 82 of a corresponding tip adapter 50. It should be emphasized that “first” and “second” are used herein for descriptive convenience and do not imply any order or particular structural arrangement. In the tip adapters, at least one (usually two) adapter legs will be associated with two anti-bend stabilizers, each contacting a different constraint flange. In a practical implementation strategy, the anti-bend stabilizers 88 are arranged in a plurality of upper pairs and a plurality of lower pairs, each of the upper pairs being coupled to an upper adapter leg 58 and each of the lower pairs being coupled to a lower adapter leg 60, as in Figure 5 Clearly visible in the view. The first constraint flange 80 and the second constraint flange 82, and, by analogy, the third constraint flange 84 and the fourth constraint flange 86, each include a side-facing contact surface 100, a base contact surface 102, and a rear-facing contact surface 104, which, the base contact surface, and the rear-facing contact surface together form a cutout 106 in a corresponding one of the upper adapter leg 58 and the lower adapter leg 60. Each corresponding cutout 106 may include a three-sided cutout as illustrated.

[0027] The tip adapter 50 may also include a curved connector portion 59 that forms a C-shape together with the upper adapter leg 58 and the lower adapter leg 60, and a tip mount 62 extends forward from the curved connector portion 59. Figure 5 As depicted, the tip adapter 50 defines a vertical plane 90 that extends vertically through the tip adapter 50 and the adapter body 51, and is equidistantly located between opposing sides 76 and 78. It may also be noted from the figures that each of the first constraint flange 80 and the second constraint flange 82 originates at the rear adapter end 54 and extends forward from the rear adapter end 54. Each base contact surface 102 may be laterally inclined outward from the contact surface 100 facing the corresponding side in the direction of the working tool lip 22.

[0028] A horizontal plane 92 is defined between an upper inner surface 66 and a lower inner surface 67. Each base contact surface 102 may define an angle 94 with respect to the horizontal plane 92, which opens laterally inward and in some embodiments is in the range of 5º to 60º. A flange length 108 in the front-to-back direction is defined by the base contact surface 102. A flange height 110 is perpendicular to the flange length 108 and is defined between the base contact surface 106 and the mounting groove 56 / upper inner surface 67. The flange length 108 is greater than the flange height 110.

[0029] In a practical implementation, the flange length 108 ranges from 100 mm to 300 mm, and the flange height 110 ranges from 5 mm to 100 mm. Flange depth dimensions (approximately for entry and exit) Figure 6 The paper size (of the adapter) can range from 5 mm to 30 mm. Furthermore, these size ranges provide sufficient contact within the available package space for the corresponding components to significantly suppress bending of the tip adapter 50, while ensuring the structural integrity of the components, especially in response to downward loads as further discussed herein. Figure 6 Side view and Figure 7 The perspective view also shows that each of the rearward-facing contact surface 104 and the side-facing contact surface 100 can be vertically oriented and define a bullnose-shaped profile in the lateral and rearward directions, respectively.

[0030] Still referencing Figures 8 to 12 Additional features of the anti-bending stabilizer 88 are shown. The anti-bending stabilizer 88 includes a stabilizer body 89, typically a metal casting or forging machined to a form suitable for use, and sometimes used interchangeably herein with anti-bending stabilizer 88. The stabilizer body 89 includes a base 96 having a downward-facing weld surface 114 defining a footprint area that is at least partially curved. The weld surface 114 includes an outer perimeter 116, which may have an elliptical shape defining two foci 120. The stabilizer body 89 also includes a peripheral weld surface 118 adjacent to and extending upward and outward from the downward-facing weld surface 114. The peripheral weld surface 118 may be at least partially conical. The downward-facing weld surface 114 may be planar. The peripheral weld surface 118 may extend upward from the downward-facing weld surface 114 to a perimeter edge 140, the shape of which conforms to the shape of the outer perimeter 116.

[0031] The stabilizer body 89 also includes a neck 122 and a clamping head 98, which extends outward from the neck 122 and has multiple contact surfaces thereon. Starting at the peripheral edge at 140 is a neck surface 134, which extends upward and transitions to the clamping head 98 via a concave curved transition surface 136 and a concave curved transition surface 138. Transition surface 136 may define a smaller radius of curvature, and transition surface 138 may define a larger radius of curvature. From Figure 11 The view in the middle shows most clearly that the neck 122 gradually tapers upward from the base 96.

[0032] The plurality of contact surfaces may include: a terminal end surface 126 facing outward from the base 96, a first near-terminal side surface 128, a second near-terminal side surface 130, and a near-terminal lower surface 132. The first near-terminal side surface 128 and the second near-terminal side surface 130 may be oriented perpendicular to the terminal end surface 126. The near-terminal lower surface 132 may be oriented obliquely to the terminal end surface 126 and substantially match the slope of the base contact surface 102. The terminal end surface 126 may be rectangular, and each of the plurality of contact surfaces may be planar.

[0033] For example Figure 8 , Figure 9 and Figure 11 As illustrated, multiple contact surfaces may include certain dimensions or ranges of length and height, their structure designed to provide a desired interface for contact with the surfaces forming the corresponding constraint flanges discussed herein. The terminal end surface 126 defines a height 144. The height 144 may range from 5 mm to 100 mm. The first proximal end surface 128 and the second proximal end surface 130 may define equal lengths 142. The proximal lower surface 132 may define a length 146 and a width 148. The width of the terminal end surface 126 may be equal to the length 146. In specific embodiments, the length 142 may range from 10 mm to 200 mm. The width 148 may range from 5 mm to 30 mm. The length 146 may range from 100 mm to 300 mm. It should be understood that the terms “length,” “width,” and “height” are used herein for descriptive convenience only, and the specific dimensions mentioned herein may also be understood with reference to the accompanying drawings.

[0034] Industry Applicability

[0035] Referring now to the accompanying drawings, the tooling assemblies, tooling lips, tip adapters, and anti-bend stabilizers according to this disclosure are available for sale as original equipment installed on machines or machine parts (such as buckets). In other cases, the tooling lip may be sold as a separate complete assembly or as a system of related but unassembled parts. Any of these components may also be supplied as replacement parts suitable for field installation.

[0036] When the tip adapter 50 is to be mounted on the tool lip 26, the tip adapter 50 can be slid into place to receive the forward lip edge 34 within the mounting slot 56, and the tip adapter 50 can be spot-welded to the appropriate position on the tool lip. The bend stabilizers 88 can then be positioned on both the upper and lower sides of the tool lip 26 based on the temporarily positioned tip adapter 50, and spot-welded to the appropriate position on the tool lip 26. The tip adapter 50 can then be removed, and the process repeated for each upper and lower pair of bend stabilizers 88. With all bend stabilizers in place, they can be fully welded to the tool lip 26. Each tip adapter 50 can then be installed by sliding it into place again to contact the bend stabilizer with the constraint flange, and secured, for example, by means of the wedge assembly 70 and / or any other fixing, positioning, or support hardware that may be used. Removing the tip adapter 50 may include removing any encapsulating material (such as soil, etc.) that has entered or between the tip adapter 50 and the associated hardware, disengaging the wedge assembly 70, and sliding the tip adapter 50 off the working tool lip 26.

[0037] During field use, it has been observed that the tooth tip 28 can withstand various types of loads, including lateral loads, end loads, and downward loads. Theoretically, any of these types of loads could cause displacement and / or bending of the tip adapter. It is conceivable that the tip adapter may not actually be welded to the tool lip. In particular, downward loads (where a downward force may be applied to the tooth tip during maintenance) could cause the rear adapter end to tend to lift off the upper lip surface. Loads oriented in the opposite direction are expected to have roughly the opposite effect. Over time, repeated exposure to such conventional loads could lead to loosening, displacement, or failure of the associated tip adapter, ultimately affecting machine performance and / or requiring undesirable downtime for repairs. According to this disclosure, the combination of the tip adapter and anti-bending stabilizer geometry improves the clamping effect of the tip adapter under such loads, ultimately limiting the extent to which downward loads and potentially other loads could cause equipment damage and / or performance degradation.

[0038] This specification is for illustrative purposes only and should not be construed as limiting the scope of this disclosure in any way. Therefore, those skilled in the art will understand that various modifications can be made to the currently disclosed embodiments without departing from the full and reasonable scope and spirit of this disclosure. Other aspects, features, and advantages will become apparent from a study of the accompanying drawings and appended claims. As used herein, the articles “a” and “an” are intended to include one or more items and may be used interchangeably with “one or more.” The term “an” or similar language is used where only one item is intended. Furthermore, as used herein, the term “having” is intended to be an open-ended term. Further, the phrase “based on” is intended to mean “at least partially based on” unless otherwise explicitly stated.

Claims

1. A work tool component (22), the work tool component comprising: The working tool lip (26) includes an upper lip surface (30) and a lower lip surface (32), the upper lip surface and the lower lip surface each extending backward from the front to the lip edge (34); A plurality of tip adapters (50) are arranged laterally along the forward lip edge and each includes a front adapter end (52), a rear adapter end (54), and a mounting slot (56) that receives the forward lip edge and extends forward from the rear adapter end, and each mounting slot is defined between an upper adapter leg (58) that contacts the surface of the upper lip and a lower adapter leg (60) that contacts the surface of the lower lip; At least one of the upper adapter leg and the lower adapter leg in each tip adapter includes a first constraint flange (80, 84) and a second constraint flange (82, 86) on their opposite sides, respectively. and Multiple anti-bend stabilizers (88) each having a base (96) and a clamping head (98), the base being attached to the working tool lip at a position on the side of one of the multiple tip adapters, the clamping head extending outward from the base and contacting one of the first constraint flange or the second constraint flange of a corresponding tip adapter of the multiple tip adapters.

2. The work tool assembly of claim 1, wherein the plurality of anti-bend stabilizers are arranged as a plurality of upper pairs and a plurality of lower pairs, each of the plurality of upper pairs being coupled to the upper adapter leg of one of the plurality of tip adapters, and each of the plurality of lower pairs being coupled to the lower adapter leg of one of the plurality of tip adapters. The working tool assembly further includes a plurality of forward tooth tips (28) and a plurality of backward tooth tips (36), each of the plurality of forward tooth tips being mounted to a corresponding tip adapter among the plurality of tip adapters, and the plurality of backward tooth tips being arranged laterally along the edge of the forward lip and alternating with the plurality of forward tooth tips; and The tool lip includes a bucket lip having a first upturned outer lip edge (38) and a second upturned outer lip edge (40), and each of the upper lip surface and the lower lip surface extends laterally between the first upturned outer lip edge and the second upturned outer lip edge.

3. The work tool assembly according to claim 1 or 2, wherein each of the first constraint flange and the second constraint flange extends forward from the respective rear adapter end and forms a rearward-facing contact surface (104), a side-facing contact surface (100), and a base contact surface (102), and the respective anti-bend stabilizer contacts each of the rearward-facing contact surface, the side-facing contact surface, and the base contact surface; and Each base contact surface is laterally inclined outward along the direction of the working tool lip.

4. The working tool assembly according to any one of claims 1 to 3, wherein the clamping head includes a terminal end surface (126) in contact with the side-facing contact surface, a near-terminal lower surface (132) in contact with the base contact surface, and a near-terminal side surface (128, 130) in contact with the rear-facing contact surface.

5. A tip adapter (50) for a working tool (24), said tip adapter comprising: The adapter body (51) includes a front adapter end (52) having a tip mount (62), a rear adapter end (54) and a mounting groove (56) defined between an upper adapter leg (58) and a lower adapter leg (60) for receiving a forward lip edge (34) of a working tool lip (26) and extending forward from the rear adapter end; At least one of the upper adapter leg and the lower adapter leg includes a first constraint flange (80, 84) and a second constraint flange (82, 86) on their opposite sides, respectively; and The first constraint flange and the second constraint flange each include a side-facing contact surface (100), a base contact surface (102), and a rear-facing contact surface (104), wherein the side-facing contact surface, the base contact surface, and the rear-facing contact surface together form a cutout (106) in one of the upper adapter leg or the lower adapter leg.

6. The tip adapter of claim 5, wherein the cut comprises a three-sided cut, and wherein the at least one of the upper adapter leg and the lower adapter leg comprises both the upper adapter leg and the lower adapter leg.

7. The tip adapter according to claim 5 or 6, wherein: The adapter body includes a curved connector portion (59) that forms a C-shape together with the upper adapter leg and the lower adapter leg, and the tip mount extends forward from the curved connector portion; and The adapter body is planar symmetrical within the upper adapter leg and the lower adapter leg about a vertical extension extending through the adapter body and located equidistantly between the opposite sides.

8. The tip adapter according to any one of claims 5 to 7, wherein each of the first constraint flange and the second constraint flange originates at the rear adapter end, and each base contact surface is inclined outward from the contact surface facing the respective side.

9. The tip adapter of claim 8, wherein a horizontal plane is defined between the upper adapter leg and the lower adapter leg, and each base contact surface defines an angle of inclination relative to the horizontal plane, the angle of inclination being laterally inward and in the range of 5° to 60°.

10. The tip adapter according to any one of claims 5 to 9, wherein the flange length in the front-to-back direction is defined by the base contact surface, and the flange height is defined between the base contact surface and the mounting groove, and the flange length is greater than the flange height.

11. The tip adapter of claim 10, wherein each of the rearward-facing contact surface and the side-facing contact surface is vertically oriented and defines a bullnose profile in the lateral and rearward directions, respectively.

12. A bend stabilizer (88) for a work tool (24), the bend stabilizer comprising: The stabilizer body (89) includes a base (96) having a downward-facing welding surface (114) and a peripheral welding surface (118), the downward-facing welding surface defining a footprint area that is at least partially curved, and the peripheral welding surface adjacent to and extending upward and outward from the downward-facing welding surface; The stabilizer body also includes a neck (122) and a clamping head (98), the clamping head extending outward from the neck and having a plurality of contact surfaces thereon; and The plurality of contact surfaces include: a terminal end surface (126) facing outward from the base, a first near-terminal side surface (128), a second near-terminal side surface (130), and a near-terminal lower surface (132).

13. The anti-bending stabilizer of claim 12, wherein the footprint area comprises an elliptical footprint area, and the neck tapers gradually upward from the base, and wherein each of the first proximal end side surface and the second proximal end side surface is oriented perpendicular to the end end surface, and the proximal lower surface is oriented obliquely to the end end surface.

14. The anti-bending stabilizer according to claim 12 or 13, wherein the terminal end surface is rectangular, and each of the plurality of contact surfaces is planar.

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