Combination screws and a synchronous transfer method for encoders based on combination screws

Abstract

This invention relates to the field of encoder technology, and more particularly to a combination screw and a method for synchronous encoder transfer based on the combination screw. The combination screw includes: a first stud and a second stud; a first drive groove is provided on the head of the first stud; a connecting hole is provided on the first stud or the second stud; the inner wall of the connecting hole is provided with internal threads; the first stud and the second stud are screwed together by the internal threads, and at least part of the end of the second stud extends out of the first stud; a second drive groove is provided on the end of the second stud facing the first stud; wherein, the combination screw is configured to allow a wrench to pass through the through hole of the first stud and engage with the second drive groove to drive the second stud to move axially along the through hole. The advantage of this invention is that, by using this combination screw and combining it with a series of operating methods, the synchronous transfer of the encoder from the tooling shaft system to the user end can be achieved, and the encoder installation can be completed without additional tools or multiple reversing operations, simplifying the installation and adjustment process.

Description

Technical Field

[0001] This invention relates to the field of encoder technology, and in particular to a combination screw and an encoder synchronous transfer method based on the combination screw. Background Technology

[0002] Based on structural characteristics, grating rotary encoders can be divided into integral encoders and split encoders. Integral encoders are characterized by bearings that are connected to the main body and the main shaft respectively, and the three are integrated into a shaft system. Therefore, the rotation center of the main shaft is fixed relative to the main body. Split encoders, on the other hand, do not have bearings, so the main body and the main shaft are independent of each other.

[0003] When using a split encoder, the spindle rotation center needs to be fixed relative to the main body. Therefore, when the manufacturer assembles and adjusts the split encoder, they will first refer to the shaft system of the integral encoder to customize a shaft system fixture, fix the encoder spindle to the fixture spindle, and fix the main body to the fixture body, thereby achieving the purpose of fixing the relative position of the spindle rotation center to the main body.

[0004] However, when transporting a split-type encoder, the encoder must be disassembled from the tooling shaft system. During disassembly and transportation, the relative positions of the main body and spindle must not be altered; otherwise, the relative positions of the encoder body and spindle after user installation will differ from those during manufacturer's assembly and adjustment, affecting product accuracy. In existing technology, split-type encoders typically use transport connecting screws that pass through the main body and then lock the spindle, fixing the main body and spindle as a single unit. Therefore, during actual installation, the user must first remove the transport connecting screws and then replace them with another screw to fix the encoder spindle to the user-end rotor. Each time a transport connecting screw is removed, the spindle loses its locking force in that direction and undergoes slight displacement due to residual stress; when a new screw is installed, the relative position of the spindle and main body is different from its transport state. This disassembly and assembly process is both cumbersome and inevitably alters the spindle position. Summary of the Invention

[0005] Based on this, the present invention proposes a combination screw and an encoder synchronous transfer method based on the combination screw. By replacing the above-mentioned transport connection screw with the combination screw, the main body and main shaft of the split encoder are relatively fixed during disassembly and transportation. At the same time, it is convenient for users to complete the final fixation of the main shaft and the user-end rotor directly by tightening the second stud inside the combination screw without disassembling the above-mentioned transport connection screw during actual installation, thereby improving installation efficiency.

[0006] To achieve the above objectives, the technical solution of this invention is implemented as follows: a combination screw for fixing an encoder includes: a first stud and a second stud that are threadedly engaged with each other, with at least a portion of the end of the second stud protruding from the first stud; the first stud is provided with a screw head and an axially penetrating through hole; the screw head is provided with a first drive groove; a connecting hole is provided on the first stud or the second stud; the inner wall of the connecting hole is provided with an internal thread, and the diameter of the connecting hole is larger than the diameter of the through hole; the first stud and the second stud are screwed together by the internal thread; a second drive groove is provided at the end of the second stud facing the first stud; the second drive groove communicates with the through hole; wherein, the combination screw is configured to allow a wrench to pass through the through hole of the first stud and engage with the second drive groove to drive the second stud to move axially along the through hole.

[0007] Furthermore, a connecting hole is provided on the first stud.

[0008] Furthermore, the connecting hole is located on the second stud, and the second drive groove is located at the bottom of the connecting hole.

[0009] Furthermore, the first drive slot and the second drive slot are one of a cross slot, a slotted slot, or an internal hexagonal slot.

[0010] An installation method for synchronously transferring an encoder from a shaft tooling to a user end is provided, based on the aforementioned combination screws, in conjunction with the shaft tooling and the encoder. The encoder includes a body and a spindle, with the body sleeved on the outside of the spindle. The spindle has an axial inner hole. The outer circumference of the body is uniformly provided with through screw mounting holes, and the spindle has through threaded holes at the positions corresponding to the screw mounting holes.

[0011] The shaft system tooling includes a tooling spindle and a tooling body. The connection end structure of the tooling spindle is the same as the connection end structure of the user-end rotor, and is used to connect to the spindle. The mounting interface of the tooling body is the same as the mounting interface of the user-end stator, and is used to connect to the body.

[0012] The installation method for synchronously transferring the encoder from the shaft tooling to the user end includes the following steps:

[0013] S1: In-plant assembly and adjustment stage:

[0014] S11: Create a matching permanent serial number on the outer surface of the main body corresponding to the screw mounting hole position, and on the outer surface of the spindle corresponding to the threaded hole position;

[0015] S12: First, connect the encoder body to the mounting interface of the tooling body; place the encoder spindle onto the connecting end of the tooling spindle, so that the serial number on the spindle corresponds one-to-one with the serial number on the body; then, in sequence, pass multiple standard set screws through the screw mounting holes on the body and screw them into the threaded holes on the spindle until the ends of each standard set screw press against the connecting end of the tooling spindle, thereby connecting the spindle to the shaft system tooling.

[0016] S2: Transportation Stage: First, according to the sequence number determined in step S11, remove the first standard set screw through the screw mounting hole of the main body; then, use a wrench to screw a combination screw into the first drive groove, so that the second stud is screwed into the threaded hole of the main shaft, and continue to tighten the first stud until the first stud is locked to the main body; repeat this process, and remove all the remaining standard set screws one by one according to this sequence number, and replace the corresponding combination screws; after all the standard set screws in the circumferential direction have been replaced, the encoder's main shaft is disengaged from the shaft system tooling, and the main shaft is locked to the main body as one unit.

[0017] S3: User-end installation stage: First, place the encoder on the connection end of the user-end rotor so that the main body contacts the mounting surface of the user-end stator and fix the main body on the mounting surface of the user-end stator; then, in sequence, use a wrench to adjust the second stud through the second drive groove so that its end presses against the user-end rotor, thereby completing the connection between the main shaft and the user-end rotor.

[0018] Furthermore, in step S3, when the end of the second stud presses against the user-end rotor, the second stud completely disengages from the first stud; at the same time, there is a gap between the end of the first stud and the outer surface of the spindle.

[0019] Furthermore, the number of screw mounting holes and threaded holes is at least three.

[0020] The present invention can achieve the following beneficial effects:

[0021] 1) By using this combination of screws with shaft tooling, the relative position of the encoder body and the main shaft can be kept unchanged when the encoder is disassembled, further ensuring that the relative position of the encoder body and the main shaft is consistent with the factory assembly and adjustment during transportation and after user installation.

[0022] 2) During the user-end installation phase, the wrench passes through the through hole of the first stud and directly drives the second drive groove of the second stud. Without disassembling the transport connection screws, additional tools and reversing operations are eliminated, and the final fixation of the spindle and the user-end rotor can be completed, simplifying the assembly process.

[0023] 3) By using the installation method of the present invention, the encoder spindle and the main body are always connected as one unit during the user-end installation stage with the help of combination screws, so as to maintain the relative positional relationship between the two during the transportation stage on the user-end installation interface and keep the spindle position unchanged. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0025] Figure 1 This is a schematic diagram of the combined screw according to Embodiment 1 of the present invention;

[0026] Figure 2 This is a schematic diagram of the combined screw according to Embodiment 2 of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of the first stud in Embodiment 1 provided by the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the second stud in Embodiment 2 provided by the present invention;

[0029] Figure 5 This is a schematic diagram of the structure of a split encoder provided according to an embodiment of the present invention;

[0030] Figure 6 This is a structural schematic diagram of the combined screw connection body and the spindle according to Embodiment 1 of the present invention;

[0031] Figure 7 This is a schematic diagram of the combined screw connection body and spindle provided in Embodiment 2 of the present invention;

[0032] Figure 8 This is a schematic diagram of the combined screw connection encoder and shaft tooling according to Embodiment 1 of the present invention.

[0033] The reference numerals in the attached drawings include: 1, first stud; 11, screw head; 12, through hole; 13, first drive groove; 2, second stud; 21, second drive groove; 3, connecting hole; 31, internal thread; 4, encoder; 41, main body; 42, spindle; 5, shaft tooling; 51, tooling spindle; 52, tooling main body. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not 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 on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] The invention will now be described in detail with reference to specific embodiments.

[0039] like Figures 1 to 8 As shown in the figure, an embodiment of the present invention provides a combination screw for fixing an encoder, comprising: a first stud 1 and a second stud 2 that are threadedly engaged with each other, wherein at least part of the end of the second stud 2 protrudes from the first stud 1. The first stud 1 is provided with a screw head 11 and an axially penetrating through hole 12, and the screw head 11 is provided with a first drive groove 13. The first stud 1 or the second stud 2 is provided with a connecting hole 3, and the inner wall of the connecting hole 3 is provided with an internal thread 31. The diameter of the connecting hole 3 is larger than the diameter of the through hole 12. The second stud 2 is provided with a second drive groove 21. The second drive groove 21 communicates with the through hole 12.

[0040] Example 1:

[0041] like Figure 1 , Figure 3 As shown, the connecting hole 3 is provided on the first stud 1. The connecting hole 3 is located at the end of the first stud 1 facing the second stud 2, and its axis coincides with the axis of the through hole 12, forming a stepped hole with the through hole 12. The inner wall of the connecting hole 3 is provided with an internal thread 31, and the second stud 2 is screwed to the first stud 1 through the internal thread 31.

[0042] The second drive groove 21 is located at the end of the second stud 2 facing the first stud 1. A wrench passes through the through hole 12 of the first stud 1 and engages with the second drive groove 21 to drive the second stud 2 to move axially along the through hole 12. In this embodiment, the second stud 2 is an internal hexagon set screw.

[0043] Example 2:

[0044] like Figure 2 and Figure 4 As shown, a connecting hole 3 is provided on the second stud 2, and the inner wall of the connecting hole 3 is provided with an internal thread 31 for screwing with the first stud 1. A second drive groove 21 is provided at the bottom of the connecting hole 3. The first stud 1 is screwed to the second stud 2 through the internal thread 31 of the connecting hole 3. A wrench passes through the through hole 12 of the first stud 1 and engages with the second drive groove 21 to drive the second stud 2 to move axially along the through hole 12.

[0045] The first drive slot 13 and the second drive slot 21 are one of a cross slot, a slot, or a hexagonal socket. The slot shapes of the first drive slot 13 and the second drive slot 21 can be the same or different.

[0046] The wrench passes through the through hole 12 of the first stud 1 and directly drives the second drive groove 21 of the second stud 2. No additional tools or multiple reversing operations are required, making it especially suitable for narrow spaces and simplifying the assembly and adjustment process.

[0047] The appropriate combination screws can be selected according to the structure of different encoder models.

[0048] An installation method for synchronously transferring an encoder from a shaft fixture to the user end is provided, based on the aforementioned combination screws, in conjunction with the shaft fixture 5 and the encoder 4. The encoder 4 includes a body 41 and a spindle 42, with the body 41 sleeved on the outside of the spindle 42. Through screw mounting holes are evenly distributed around the outer periphery of the body 41, and threaded holes are provided on the spindle 42 at positions corresponding to the screw mounting holes.

[0049] The shaft fixture 5 includes a fixture spindle 51 and a fixture body 52. ​​The connection end structure of the fixture spindle 51 is the same as that of the user-end rotor, and it is used to connect to the spindle 42. The mounting interface of the fixture body 52 is the same as that of the user-end stator, and it is used to connect to the body 41. In this embodiment, there are three screw mounting holes and three threaded holes, and the screw mounting holes are stepped holes.

[0050] It should be noted that the mounting interface of the user-end stator refers to the mounting threaded hole used for mounting with the main body 41. The mounting interface of the main body 41 refers to the mounting hole used for connecting with the mounting interface of the user-end stator.

[0051] The installation method for synchronously transferring the encoder from the shaft tooling to the user end includes the following steps:

[0052] S1: In-plant assembly and adjustment stage:

[0053] S11: Create a pairing permanent serial number on the outer surface of the main body 41 corresponding to the screw mounting hole position and on the outer surface of the spindle 42 corresponding to the threaded hole position.

[0054] S12: First, connect the body 41 of the encoder 4 to the mounting interface of the tooling body 52; fit the main shaft 42 of the encoder 4 onto the connecting end of the tooling main shaft 51, so that the serial number on the main shaft 42 corresponds one-to-one with the serial number on the body 41. Then, in sequence, pass multiple standard set screws through the screw mounting holes on the body 41 and screw them into the threaded holes on the main shaft 42 until the ends of each standard set screw press against the connecting end of the tooling main shaft 51, thereby connecting the main shaft 42 to the shaft tooling 5.

[0055] Specifically, during factory assembly and adjustment of encoder 4, firstly, permanent serial numbers 1, 2, and 3 are made on the outer surface of the main body 41 corresponding to the three screw mounting holes. Then, matching serial numbers 1, 2, and 3 are made on the outer surface of the spindle 42 corresponding to the three threaded holes.

[0056] In some implementations, the permanent serial number can also be I, II, III.

[0057] Next, place the encoder 4 body 41 onto the tooling body 52 of the shaft system tooling 5. Use an Allen screw to pass through the body 41 and screw it into the mounting threaded hole of the tooling body 52 to lock the two together. Then, fit the encoder 4 spindle 42 onto the tooling spindle 51 of the shaft system tooling 5, so that the serial numbers on the spindle 42 correspond one-to-one with the serial numbers on the body 41 (i.e., 1, 2, and 3 on the spindle 42 correspond one-to-one with 1, 2, and 3 on the body 41, respectively). Then, in sequence according to the serial numbers, use standard set screws to pass through the corresponding screw mounting holes on the body 41 and screw them into the threaded holes of the spindle 42 until the end of the standard set screw presses against the connecting end of the tooling spindle 51, locking the two together.

[0058] It should be noted that when the first standard set screw is used to abut against the tooling spindle 51 through the threaded hole of the spindle 42, the spindle 42 of the encoder 4 will shift, and this shift will be the largest. Each subsequent screwing in of a standard set screw will cause a corresponding shift in the spindle 42 of the encoder 4. Therefore, the sequence numbers need to be marked in advance to ensure the consistency of the spindle 42's shift state during the disassembly and assembly in subsequent steps S2 and S3.

[0059] S2: Transportation stage: First, according to the sequence number determined in step S11, take out the first standard set screw through the screw mounting hole of the main body 41; then, use a wrench to screw a combination screw through the first drive groove 13 to screw the second stud 2 into the threaded hole of the main shaft 42, and continue to tighten with the wrench until the first stud 1 is locked to the main body 41.

[0060] Repeat this process, removing all remaining standard set screws one by one according to the sequence number, and replacing the corresponding combination screws; after all standard set screws in the circumferential direction have been replaced, the main shaft 42 of the encoder 4 is disengaged from the shaft fixture 5, and the main shaft 42 is locked together with the main body 41.

[0061] Specifically, after removing the first standard set screw (corresponding to serial number 1), screw in the first combination screw. Use a wrench to apply force to the first drive groove 13 of the first stud 1, so that the second stud 2 is screwed into the threaded hole of the main shaft 42. Continue to tighten the first stud 1 until the first stud 1 is locked to the body 41. Then, repeat this process, replacing the remaining two standard set screws with combination screws one by one according to the serial number of step S11. After all the standard set screws in the circumferential direction have been replaced, the main shaft 42 of the encoder 4 is disengaged from the shaft fixture 5, and the main shaft 42 is locked to the body 41 as one unit, ensuring the relative position between the body 41 and the main shaft 42 during transportation.

[0062] It should be noted that the spindle 42 and the tooling spindle 51 have a clearance fit. When the spindle 42 is tightened using a standard set screw, because the tooling spindle 51 is fixed, the spindle 42 will move in the opposite direction of the standard set screw's insertion during the tightening process until the standard set screw is fully tightened. Similarly, when the spindle 42 and the main body 41 are tightened using a combination screw, because the main body 41 is now fixed to the tooling main body 52 by an internal hexagonal screw, and the main body 41 is not moving, when the screw head 11 of the first stud 1 in the combination screw abuts against the stepped hole of the mounting hole, the combination screw cannot be further inserted. Continuing to tighten the combination screw will cause the spindle 42 to move in the opposite direction of the combination screw's insertion until the combination screw is fully tightened with the spindle 42.

[0063] Comparing the use of standard set screws and combination screws to tighten the main shaft 42, it is found that the main shaft 42 moves in the opposite direction of the screw's screw insertion. This means that replacing the standard set screw with the combination screw does not change the eccentric direction of the main shaft 42, ensuring that the relative positions of the encoder 4's main shaft 42 and body 41 remain completely unchanged. Therefore, when the encoder 4 is removed from the shaft system fixture 5, the relative positional relationship between the main shaft 42 and body 41 is the same as when it was on the fixture shaft system. During transportation, the positions of the main shaft 42 and body 41 will not change due to the combination screws. When the user installs the encoder, they can tighten the second stud 2 in the same order as when replacing the combination screws, ensuring that the relative positions of the encoder 4's main shaft 42 and body 41 are consistent with those on the shaft system fixture 5 after installation.

[0064] S3: User-end installation stage: First, the encoder 4 is fitted onto the connection end of the user-end rotor, so that the main body 41 contacts the mounting surface of the user-end stator, and the main body 41 is fixed on the mounting surface of the user-end stator; then, in sequence, the second stud 2 is adjusted by using a wrench through the second drive groove 21 so that its end presses against the user-end rotor, thus completing the connection between the main shaft 42 and the user-end rotor.

[0065] It should be noted that by tightening the second stud 2 in the same order as when replacing the combination screws, the relative positions of the encoder 4 spindle 42 and body 41 after installation by the user will be consistent with those on the shaft tooling 5.

[0066] This combination screw enables a unified connection between the encoder body 41 and the spindle 42 during the two key stages of transportation and user installation.

[0067] Transportation stage: By using this combination of screws and a series of operating methods, the main shaft 42 and the main body 41 of the encoder 4 are fixed together as one unit without changing their relative positional relationship, and can be removed from the shaft fixture 5. This also prevents the main shaft 42 and the main body 41 from loosening during transportation.

[0068] User installation phase: The main shaft 42 of the direct encoder 4 can be locked to the user-end rotor using this combination screw, without the need to introduce other parts.

[0069] This design simplifies the traditional multi-step operation into a single assembly process, reducing labor costs.

[0070] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method of installing an encoder from a shafting tooling synchronous transfer to a user end, based on a combination screw, which is implemented in cooperation with a shafting tooling and an encoder; the combination screw comprising: The first stud and the second stud are threadedly engaged with each other, and an end of the second stud at least partially protrudes from the first stud; The first stud is provided with a screw head and an axial through hole; the screw head is provided with a first driving groove; The first stud or the second stud is provided with a connecting hole; the inner wall of the connecting hole is provided with an internal thread, and the diameter of the connecting hole is greater than that of the through hole; The first stud and the second stud are threadedly connected through the internal thread; an end of the second stud towards the first stud is provided with a second driving groove; the second driving groove is in communication with the through hole; The combined screw is configured to allow a wrench to pass through the through hole of the first stud and engage with the second driving groove to drive the second stud to move along the axial direction of the through hole; the encoder comprises a main body and a main shaft, the main body is sleeved on the outside of the main shaft; the main shaft is provided with an axial inner hole; the outer periphery of the main body is uniformly provided with a through screw mounting hole, and the main shaft is provided with a through thread hole corresponding to the position of the screw mounting hole; The shafting tool comprises a tool main shaft and a tool main body, the connection end structure of the tool main shaft is the same as that of the user end rotor, and is used for being connected with the main shaft; the mounting interface of the tool main body is the same as that of the user end stator, and is used for being connected with the main body; The method for synchronously transferring the encoder from the shafting tool to the user end comprises the following steps: S1: factory installation and adjustment stage: S11: permanent serial numbers are made on the positions of the screw mounting holes on the outer surface of the main body and the positions of the thread holes on the outer surface of the main shaft; S12: firstly, the main body of the encoder is connected with the mounting interface of the tool main body; the main shaft of the encoder is sleeved on the connection end of the tool main shaft, so that the serial numbers on the main shaft correspond to the serial numbers on the main body one by one; then, a plurality of standard set screws are sequentially inserted through the screw mounting holes on the main body and screwed into the thread holes on the main shaft in the order of the serial numbers, until the end of each standard set screw is pressed against the connection end of the tool main shaft, so that the main shaft is connected with the shafting tool; S2: transportation stage: firstly, the first installed standard set screw is taken out through the screw mounting hole of the main body in the order of the serial numbers determined in step S11; then, a combined screw is screwed into one of the combined screws through the first driving groove using a wrench, so that the second stud is threadedly connected with the thread hole of the main shaft, and the first stud is continuously screwed until the first stud is locked with the main body; the above process is repeated, and all the remaining standard set screws are taken out one by one in the order of the serial numbers, and the corresponding combined screws are replaced; after the replacement of all the standard set screws in the circumferential direction is completed, the main shaft of the encoder is separated from the shafting tool, and the main shaft is locked with the main body as a whole; S3: User end installation stage: first, the encoder is set on the connecting end of the user end rotor, the main body is in contact with the user end stator installation surface, and the main body is fixed on the user end stator installation surface; then, in sequence, the second stud is adjusted by using a wrench through the second driving slot, so that the end portion of the second stud is pressed against the user end rotor, thereby completing the connection of the main shaft and the user end rotor.

2. The method of claim 1, wherein the encoder from shafting tooling synchronous transfer to user end installation method, characterized in that, In step S3, when the end portion of the second stud is pressed against the user end rotor, the second stud is completely separated from the first stud; at the same time, there is a gap between the end portion of the first stud and the outer surface of the main shaft.

3. The method of claim 1, wherein the encoder from shafting tooling synchronous transfer to user end installation method, characterized in that, The number of the screw mounting holes and the threaded holes is at least three.

4. The method of claim 1, wherein the encoder from shafting tooling synchronous transfer to user end installation method, characterized in that, The first driving slot and the second driving slot are one of a cross slot, a straight slot or an internal hexagonal slot.

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