A tool and method for locating the starting point of a thread

Abstract

This invention discloses a thread start point positioning tool and method, comprising an external threaded mandrel and an internal threaded sleeve. The external threaded mandrel has a shoulder in its middle, one end of which has an external thread for engaging with the internal thread of a head cover, and the other end is a smooth shaft. The internal threaded sleeve is located on one side of the shoulder and is used to engage with the external thread at the lower end of an adjusting nut. An arc-shaped notch is provided on the circumference of the internal threaded sleeve, the position of which matches the arc-shaped notch on the outer end cap of the adjusting nut and the position of the locking hole on the head cover. The thread start point positioning tool of this invention has a simple structure and is easy to manufacture, with good assembly results. It can be used as a reference for manufacturing parts with thread start point positioning functions. Using this positioning tool and method, the assembly difficulties caused by limited space and the unique number of locking holes can be effectively solved without increasing processing difficulty.

Description

Technical Field

[0001] This invention relates to the technical field of positioning tools, and in particular to a thread starting point positioning tool and positioning method. Background Technology

[0002] During the speed controller assembly process, the head cover and adjusting worm nut are connected together by threads, and a locking pin is used to connect the adjusting worm nut's outer hexagonal recessed arc to the locking hole on the head cover to prevent the adjusting worm nut from rotating. Due to limited space in the head cover, only one locking hole can be accommodated. Before the widespread use of CNC equipment, the length dimensions of the parts were varied within tolerances, and during assembly, the parts could be swapped to align the adjusting nut's outer hexagonal recessed arc with the head cover's locking hole and complete the assembly. With the widespread use of CNC equipment, the dimensional consistency of parts in the same batch is very high. At this time, the phenomenon of misalignment between the nut's recessed arc and the head cover's locking hole is exposed during assembly. Moreover, swapping parts in the same batch is often not a solution, and the only option is to trim the part's length dimension and reassemble it, delaying production delivery time.

[0003] Existing methods for checking the thread start point are all for applications with multiple locking holes. The head cover described above only has one locking hole, making the control of the thread start point more stringent compared to conventional methods. During machining of the threaded hole end face on the head cover, a special fixture is used for fixation, and a tool setting block is used to measure the distance between the end faces (5±0.08mm). The thread pitch is 1.5mm. At this point, the locking hole and the thread start point can move within a 38.4° range. The adjusting nut has a 60° evenly distributed hexagonal concave arc, and the length from the positioning end face to the thread end face is 9-0.2-0.4mm, which is not related to its own thread start point. Therefore, it occurs that the machined part is qualified, but cannot be aligned during assembly. The difficulty lies in accurately locating the thread start point (locking point) of the measuring tool. Because the entry point of the tool is sharp during machining and difficult to align after removing the burrs from the head thread, it is usually necessary to perform a fitting after machining to ensure that the start point (arc notch and locking hole) matches, increasing the manufacturing difficulty. To enable interchangeable use of these products, a new type of thread start point positioning tool is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a thread starting point positioning tool and positioning method to solve the problems existing in the prior art, reduce the difficulty of positioning the thread starting point, and at the same time ensure assembly requirements.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a thread starting point positioning tool, including an external thread mandrel and an internal thread sleeve. The external thread mandrel has a shoulder in the middle, one end of the external thread mandrel has an external thread for engaging with the internal thread of a head cover, and the other end is a smooth shaft. The internal thread sleeve is located on one side of the shoulder and is used to engage with the external thread at the lower end of an adjusting nut. An arc-shaped notch is provided on the circumference of the internal thread sleeve, and the position of the arc-shaped notch matches the position of the arc-shaped notch on the outer end cap of the adjusting nut and the locking hole of the head cover.

[0007] Preferably, an arc-shaped notch is provided at the same circumferential position of the shoulder and the screwed-in internal threaded sleeve.

[0008] Preferably, the length of the internal threaded sleeve is at least greater than half the end thread length of the external threaded mandrel.

[0009] Preferably, the materials of the external threaded mandrel and the internal threaded sleeve both include stainless steel and carbon steel.

[0010] This invention also relates to a thread starting point positioning method. Based on the aforementioned thread starting point positioning tool, according to the position of the locking hole on the head cover, the external thread mandrel is simulated to assemble with the head cover, and the adjusting nut is simulated to assemble with the internal thread sleeve. The positions of the shoulder of the external thread mandrel and the arc-shaped notch on the internal thread sleeve are determined sequentially. The upper arc-shaped notch of the shoulder and the internal thread sleeve are machined by CNC. The threaded holes of the head cover and the adjusting nut that are matched are controlled to ensure that they are perpendicular to each other.

[0011] Preferably, a first-piece positioning tool is first machined by CNC. The first-piece positioning tool needs to determine the length from the threaded end face of the head cover to the positioning reference and the rotation direction of the tool and the fixture. The arc-shaped notch position of the adjusting nut is determined by the arc-shaped notch position of the first-piece positioning tool, thereby ensuring that the locking point of the thread of the adjusting nut is consistent each time it is machined.

[0012] Preferably, after the internal thread of the head cover and the locking hole are machined, the external thread mandrel is used to screw them in, and an arc-shaped notch with the same position as the locking hole is marked on the shoulder of the external thread mandrel, and the arc-shaped notch is machined on the shoulder.

[0013] Preferably, the external threaded mandrel is removed from the head cover, and the threaded end of the external threaded mandrel is screwed into the internal threaded sleeve. The arc-shaped notch of the internal threaded sleeve is drawn at the position of the arc-shaped notch of the external threaded mandrel, and the arc-shaped notch on the internal threaded sleeve is machined, thus determining the locking point position of the internal threaded sleeve.

[0014] Preferably, when machining the adjusting nut, the internal threaded sleeve is removed from the threaded end of the external threaded mandrel. The adjusting nut is then screwed onto the internal threaded sleeve with an arc-shaped notch. The position of an arc-shaped notch on the adjusting nut is marked on the arc-shaped notch of the internal threaded sleeve. At the same time, the position of the arc-shaped notch is marked on the original clamping fixture of the adjusting nut. The arc-shaped notch is then machined on the adjusting nut. This ensures that the locking point position of the adjusting nut and the head cover is consistent after assembly.

[0015] Preferably, six evenly distributed arc-shaped notches are marked on the original clamping fixture of the adjusting nut, and the outer hexagonal size of the adjusting nut is determined accordingly. At the same time, the outer hexagon and the six opposite arc-shaped notches are machined.

[0016] The present invention achieves the following technical effects compared to the prior art:

[0017] The thread start point positioning tool of the present invention has a simple structure and is easy to manufacture. It has a good effect after assembly. It can be used as a reference for manufacturing parts with thread start point positioning function. Using this positioning tool and this positioning method can effectively solve the problem of assembly difficulties caused by limited space and the unique number of locking holes without increasing the processing difficulty. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the thread start point positioning tool in an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the internal threaded sleeve in an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the end face structure of the internal threaded sleeve in an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the external threaded mandrel in an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the end face structure of the externally threaded mandrel in an embodiment of the present invention;

[0024] Figure 6 This is a process flow diagram of the thread start point positioning method in an embodiment of the present invention;

[0025] Among them: 1-external threaded mandrel, 2-internal threaded sleeve, 3-shoulder, 4-arc-shaped notch, 5-head cover, 6-adjusting nut, 7-locking hole. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The purpose of this invention is to provide a tool and method for locating the starting point of a thread to solve the problems existing in the prior art, reduce the difficulty of locating the starting point of the thread, and at the same time ensure assembly requirements.

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] like Figures 1 to 5 As shown: This embodiment provides a thread starting point positioning tool, including an external threaded mandrel 1 and an internal threaded sleeve 2. The external threaded mandrel 1 has a shoulder 3 in its middle. One end of the external threaded mandrel 1 has an external thread for engaging with the internal thread of the head cover 5, and the other end is a smooth shaft. The internal threaded sleeve 2 is located on one side of the shoulder 3 and is used to engage with the external thread at the lower end of the adjusting nut 6. An arc-shaped notch 4 is provided on the circumference of the internal threaded sleeve 2. The position of the arc-shaped notch 4 matches the position of the arc-shaped notch 4 on the outer end cap of the adjusting nut 6 and the locking hole 7 of the head cover 5. In this embodiment, "engaging with the head cover 5" refers to the shoulder 3 of the external threaded mandrel 1 fitting against the end face of the head cover 5.

[0031] As an optional solution, in this embodiment, an arc-shaped notch 4 is provided at the same circumferential position as the shoulder 3 and the engaged internal threaded sleeve 2. In this embodiment, engagement refers to the end face of the internal threaded sleeve 2 fitting against the end face of the shoulder 3, and the arc-shaped notch 4 on the internal threaded sleeve 2 is used to determine the position of the arc-shaped notch 4 on the adjusting nut 6.

[0032] As an optional embodiment, the length of the internal threaded sleeve 2 is at least greater than half the end thread length of the external threaded mandrel 1, facilitating engagement with the external threaded mandrel 1 and ensuring correspondence with the arc-shaped notch 4. As an optional embodiment, both the external threaded mandrel 1 and the internal threaded sleeve 2 are made of stainless steel or carbon steel.

[0033] The thread starting point positioning tool in this embodiment has a simple structure, is easy to manufacture, has low cost, and performs well after assembly and use.

[0034] Example 2

[0035] like Figure 6 As shown: This embodiment relates to a thread starting point positioning method. Based on the above-mentioned thread starting point positioning tool, according to the position of the locking hole 7 on the head cover 5, the external thread mandrel 1 and the head cover 5, the adjusting nut 6 and the internal thread sleeve 2 are simulated for assembly. The positions of the shoulder 3 of the external thread mandrel 1 and the arc-shaped notch 4 on the internal thread sleeve 2 are determined in sequence. The shoulder 3 and the arc-shaped notch 4 on the internal thread sleeve 2 are machined by CNC. The threaded holes of the head cover 5 and the adjusting nut 6 that are matched are controlled to ensure that they are perpendicular to each other. The thread starting point positioning method of this embodiment, taking blank material 45A, φ24x55 as an example, has the following specific operation steps: First, heat treat the blank material to achieve a workpiece hardness of HRC36~42; then, machine the model to machine the thread and end face of the external thread mandrel 1, requiring one-time positioning machining; screw the external thread mandrel 1 with the head cover 5 to determine the position of the arc-shaped notch 4 on the external thread mandrel 1, then combine the external thread mandrel 1 with the internal thread sleeve 2 to machine the corresponding arc-shaped notch 4 on the internal thread sleeve 2. Note that when the internal and external threads are screwed together, the end faces must be close together before the arc-shaped notch 4 can be machined; finally, all workpieces need to be deburred.

[0036] As an optional approach, in this embodiment, a first-piece positioning tool is first machined using CNC machining. This tool needs to determine the length from the threaded end face of the head cover 5 to the positioning datum, as well as the rotation direction of the tool and fixture. The position of the arc-shaped notch 4 of the adjusting nut 6 is determined by the position of the arc-shaped notch 4 of the first-piece positioning tool, thus ensuring that the locking point of the thread on the adjusting nut 6 is consistent each time it is machined. The dimensions of subsequent positioning tools can be machined with reference to the dimensional parameters of the first-piece positioning tool.

[0037] As an optional solution, in this embodiment, after the internal thread and locking hole 7 of the head cover 5 are machined, the external thread mandrel 1 is screwed in (the shoulder 3 is in contact with the end face of the head cover 5), and an arc-shaped notch 4 with the same position as the locking hole 7 is drawn on the shoulder 3 of the external thread mandrel 1, and the arc-shaped notch 4 is machined on the shoulder 3.

[0038] As an optional solution, in this embodiment, the external threaded mandrel 1 is removed from the head cover 5, and the threaded end of the external threaded mandrel 1 is screwed into the internal threaded sleeve 2 (the shoulder 3 is in contact with the end face of the internal threaded sleeve 2). The arc-shaped notch 4 of the internal threaded sleeve 2 is drawn at the position of the arc-shaped notch 4 of the external threaded mandrel 1, and the arc-shaped notch 4 on the internal threaded sleeve 2 is machined, thus determining the locking point position of the internal threaded sleeve 2.

[0039] As an optional solution, in this embodiment, when machining the adjusting nut 6, the internal threaded sleeve 2 is removed from the threaded end of the external threaded mandrel 1. The adjusting nut 6 is then screwed onto the internal threaded sleeve 2 with the arc-shaped notch 4 machined (the end face of the adjusting nut 6 and the internal threaded sleeve 2 are in contact). The position of the arc-shaped notch 4 on the adjusting nut 6 is marked on the arc-shaped notch 4 of the internal threaded sleeve 2. At the same time, the position of the arc-shaped notch 4 is marked on the original clamping fixture of the adjusting nut 6. The arc-shaped notch 4 is then machined on the adjusting nut 6. This ensures that the locking point position of the adjusting nut 6 and the head cover 5 is consistent after assembly.

[0040] As an alternative, in this embodiment, six evenly distributed arc-shaped notches 4 are marked on the original clamping fixture of the adjusting nut 6, and the outer hexagonal size of the adjusting nut 6 is determined accordingly. At the same time, the outer hexagon and the six opposite arc-shaped notches 4 are machined.

[0041] Based on the characteristics of the assembly, without changing the machining tolerances, the thread starting point positioning tool in Example 1 is used to control the relative positions of the thread starting point of the head cover 5 and the locking hole, and the thread starting point of the adjusting nut 6 and the side length of the outer hexagon. When machining the first positioning tool, the two parts can be adjusted according to the thread starting point positioning tool to ensure that the two parts are fixed in the correct installation position after screwing together. Since the positioning tool is an assembly of two workpieces, it is necessary to ensure that the arc-shaped notch 4 corresponds after simulated assembly and screwing. If the thread starting point is determined after machining the arc-shaped notch 4, it is time-consuming and laborious, and difficult to guarantee. In this example, for ease of machining, the two workpieces are manufactured separately. During the process, it is only necessary to control the threads to be perpendicular to the mating end faces. After completion, they are screwed together and tightened before machining the arc-shaped notch 4, which satisfies the comparison requirements for thread starting point positioning.

[0042] The thread start point positioning method in this embodiment can be used as a reference for manufacturing parts with thread start point positioning functions, and experiments have yielded a complete solution. This method can effectively solve the assembly difficulties caused by limited space and a single number of locking holes without increasing processing difficulty.

[0043] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A thread starting point positioning tool, characterized in that: The device includes an externally threaded mandrel and an internally threaded sleeve. The externally threaded mandrel has a shoulder in the middle. One end of the externally threaded mandrel has an external thread for engaging with the internal thread of the head cover, and the other end is a smooth shaft. The internally threaded sleeve can be threadedly connected to the external thread of the externally threaded mandrel. The shoulder and the engaged internally threaded sleeve have an arc-shaped notch at the same circumferential position. The internally threaded sleeve is used to engage with the external thread at the lower end of the adjusting nut. The arc-shaped notch at the circumferential position of the internally threaded sleeve matches the arc-shaped notch on the outer end cap of the adjusting nut and the locking hole of the head cover.

2. The thread starting point positioning tool according to claim 1, characterized in that: The length of the internal threaded sleeve is at least greater than half the length of the end thread of the external threaded mandrel.

3. The thread starting point positioning tool according to claim 1, characterized in that: The materials of both the external threaded mandrel and the internal threaded sleeve include stainless steel and carbon steel.

4. A method for locating the starting point of a thread, based on the thread starting point locating tool according to any one of claims 1-3, characterized in that: Based on the position of the locking hole on the head cover, the external threaded mandrel is used to simulate assembly with the head cover, the adjusting nut and the internal threaded sleeve. The position of the shoulder of the external threaded mandrel and the arc-shaped notch on the internal threaded sleeve are determined in sequence. The upper arc-shaped notch of the shoulder and the internal threaded sleeve are machined by CNC. The threaded holes of the head cover and the adjusting nut are controlled to match and ensure that the mating end faces are perpendicular.

5. The thread starting point positioning method according to claim 4, characterized in that: First, a first-piece positioning tool is machined using CNC machining. The first-piece positioning tool needs to determine the length from the threaded end face of the head cover to the positioning reference and the rotation direction of the tool and the fixture. The arc-shaped notch position of the adjusting nut is determined by the arc-shaped notch position of the first-piece positioning tool, thereby ensuring that the locking point of the thread of the adjusting nut is consistent each time it is machined.

6. The thread starting point positioning method according to claim 5, characterized in that: After the internal thread of the head cover and the locking hole are machined, the external thread mandrel is screwed in, and an arc-shaped notch with the same position as the locking hole is marked on the shoulder of the external thread mandrel, and the arc-shaped notch is machined on the shoulder.

7. The thread starting point positioning method according to claim 6, characterized in that: Remove the external threaded mandrel from the head cover and screw the threaded end of the external threaded mandrel into the internal threaded sleeve. Draw the arc-shaped notch of the internal threaded sleeve at the position of the arc-shaped notch of the external threaded mandrel, and machine the arc-shaped notch on the internal threaded sleeve. This determines the locking point position of the internal threaded sleeve.

8. The thread starting point positioning method according to claim 7, characterized in that: When machining the adjusting nut, the internal threaded sleeve is removed from the threaded end of the external threaded mandrel. The adjusting nut is then screwed onto the internal threaded sleeve, which has an arc-shaped notch machined on it. The position of an arc-shaped notch on the adjusting nut is marked on the arc-shaped notch of the internal threaded sleeve. At the same time, the position of the arc-shaped notch is marked on the original clamping fixture of the adjusting nut. The arc-shaped notch is then machined on the adjusting nut. This ensures that the locking point position of the adjusting nut and the head cover is consistent after assembly.

9. The thread starting point positioning method according to claim 8, characterized in that: Six evenly distributed arc-shaped notches are marked on the original clamping fixture of the adjusting nut, and the outer hexagonal size of the adjusting nut is determined accordingly. At the same time, the outer hexagon and the six opposite arc-shaped notches are machined.

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