A flexible machining device and method for internal trapezoidal thread with large length-diameter ratio

Abstract

The application discloses a flexible machining device and method for inner trapezoidal thread with large length-diameter ratio, and belongs to the technical field of machining. The machining device comprises a supporting frame, a rotating body and a jacking screw. The supporting frame is provided with a connecting groove, the rotating body is rotationally connected in the connecting groove, the rotating body comprises a U-shaped groove body, a taper hole is arranged on the outer wall of one side of the U-shaped groove body, the end of the jacking screw is semispherical, the jacking screw is screwed into the connecting hole, the end of the jacking screw is in abutment with the taper hole, the connecting hole is used for fixing the workpiece and the repeated positioning of the workpiece after rotating 180 degrees through cooperation with the jacking screw. After the workpiece and the rotating body are fixed and then loaded into the supporting frame, the end of the jacking screw is in abutment with the taper hole to realize the repeated positioning. After one side thread is turned, the jacking screw is removed, the rotating body and the workpiece are rotated 180 degrees and then loaded into the jacking screw to turn the other side. The application solves the problems of repeated positioning accuracy and tool engagement caused by machining of the inner trapezoidal thread at both ends.

Description

Technical Field

[0001] This invention belongs to the field of machining technology and relates to a method for machining trapezoidal threads, specifically a flexible machining device and method for internal trapezoidal threads with a large length-to-diameter ratio. Background Technology

[0002] Trapezoidal threads serve as power transmission and motion conversion tools, offering high transmission efficiency and precise repeatability, making them widely used in aerospace products. "Tool connection" is a very challenging and common problem in machining internal trapezoidal threads, especially when machining deep internal threads. Due to tool overhang limitations, a two-stage turning method must be used. Misalignment or mismatched thread profiles can easily occur at the connection between the two machining operations, leading to different go gauges or assembly difficulties.

[0003] A certain model of nut is made of 0Cr18Ni0Ti, an austenitic stainless steel, which is a difficult-to-machine material. The Tr16*4 nut has a trapezoidal thread length of 45mm and a thread root hole of 12mm. Figure 1 and Figure 2 As shown. Existing cutting tools cannot be formed in one step and require machining at both ends. This easily leads to misalignment or mismatched tooth profiles at the connection point, resulting in problems such as inconsistent go gauges or assembly difficulties. The specific operation in the existing technology is as follows:

[0004] 1. First, clamp the part, drill the center hole, drill a Φ12 hole with a drill bit, and then chamfer it with a 45-degree drill bit.

[0005] 2. Use a hand-ground high-speed steel tool to turn the internal thread of a Tr16*4 thread. The program uses layered feed, low speed, and shallow depth of cut.

[0006] 3. If the lead screw cannot pass smoothly, a custom trapezoidal thread tap is required to repair the thread. However, the cutting resistance is high, making it difficult to repair successfully. Summary of the Invention

[0007] This invention overcomes the shortcomings of the prior art and proposes a flexible machining device and method for internal trapezoidal threads with a large length-to-diameter ratio; it is used to solve the problems of repeated positioning accuracy and tool connection caused by machining both ends of internal trapezoidal threads.

[0008] This invention is achieved through the following technical solution:

[0009] A flexible machining device for internal trapezoidal threads with a large length-to-diameter ratio includes a support frame, a rotating body, and a set screw. The bottom of the support frame is connected to a machine tool. The support frame is provided with a connecting groove for connecting the rotating body, which is rotatably connected in the connecting groove. A connecting hole is provided on one side of the connecting groove for connecting the set screw. The rotating body includes a U-shaped groove, and the workpiece is fixedly connected to the U-shaped groove. A tapered hole is provided on the outer wall of one side of the U-shaped groove, and the tapered hole corresponds to the connecting hole. The end of the set screw is hemispherical, and the set screw is screwed in from the connecting hole so that the end of the set screw abuts against the tapered hole. The set screw and the connecting hole are used to fix the workpiece and for repeated positioning after the workpiece is rotated 180°.

[0010] Furthermore, the support frame includes a locking post at the bottom for locking and fixing to the machine tool.

[0011] Furthermore, the top of the locking column is a horizontal plane, and a first column and a second column are fixedly installed on the top surface of the locking column. The first column and the second column are parallel to each other; the top surface of the locking column, the first column and the second column together form a connecting groove.

[0012] Furthermore, the first column is provided with a bearing hole, and the second column is provided with a positioning hole. The bearing hole and the positioning hole are coaxially arranged, and the radius of the bearing hole is larger than the radius of the positioning hole. The second column is provided with two connecting holes, which are symmetrically arranged vertically with the positioning hole as the center.

[0013] Furthermore, the U-shaped channel includes a base plate and vertical plates on both sides of the base plate; the outer diameter of the vertical plates is adapted to the inner diameter of the bearing holes.

[0014] Furthermore, the base plate is provided with fixing holes, and the U-shaped groove is fixedly connected to the workpiece by bolts passing through the fixing holes.

[0015] Furthermore, a central shaft is provided on the outer wall of the vertical plate on one side of the base plate, which is used to connect with the bearing; a machining shaft is provided on the outer wall of the vertical plate on the other side of the base plate, which is used to rotatably connect with the positioning hole; the central shaft and the machining shaft are coaxially arranged.

[0016] Furthermore, the top of the vertical plate is provided with a pin hole, and a cover plate is connected between the tops of the two vertical plates. The cover plate is fixed by connecting and fixing it to the pin hole through a positioning pin.

[0017] A method for flexibly machining internal trapezoidal threads with a large length-to-diameter ratio, employing the aforementioned flexible machining device for internal trapezoidal threads with a large length-to-diameter ratio, includes the following steps:

[0018] Step 1: Fix the workpiece and the rotating body, then install the rotating body into the connecting groove of the support frame, and install the set screw so that the end of the set screw abuts against the tapered hole to achieve repeated positioning.

[0019] Step 2: Begin machining the threads on one side of the workpiece;

[0020] Step 3: After one side of the thread is finished, remove the set screw and rotate the rotating body and the workpiece 180°. After rotating 180°, adjust the phase angle to ensure that the two thread lines are evenly distributed on the circumference. Reinstall the set screw for repeated positioning and fixation, and start turning the other side of the workpiece thread.

[0021] Furthermore, before formal machining, the starting point of the trial thread cut is an integer multiple of the pitch plus a correction value from the center of rotation.

[0022] The beneficial effects of this invention compared to the prior art are as follows:

[0023] This invention enables part rotation and high repeatability positioning. With a single clamping operation and without tool removal (relative rotational relationship unchanged), it utilizes the automatic alignment and high repeatability of the spherical surface and tapered hole to achieve a thread coaxiality of ≤0.05 after the workpiece rotates 180 degrees. By utilizing the phase angle correspondence of the double-ended thread, the Z-axis origin is recalibrated, ensuring accurate positional relationship between the new coordinate system and the workpiece, avoiding tool contact issues, and guaranteeing effective fit between the screw and the thread. It also solves the problem of converting from a lack of standard tools to a standard tool. Attached Figure Description

[0024] Figure 1 This is a front view of the nut to be processed;

[0025] Figure 2 for Figure 1 Sectional view along line AA;

[0026] Figure 3 This is a three-dimensional structural schematic diagram of the support frame described in this invention;

[0027] Figure 4 This is a front view of the support frame described in this invention;

[0028] Figure 5 for Figure 4 Sectional view along the BB direction;

[0029] Figure 6 This is a front view of the rotating body of the present invention;

[0030] Figure 7 This is a side view of the rotating body of the present invention;

[0031] Figure 8 This is a top view of the rotating body of the present invention;

[0032] Figure 9 This is a side sectional view of the rotating body of the present invention;

[0033] Figure 10 This is a physical diagram of the rotating body of the present invention;

[0034] Figure 11A three-dimensional diagram showing the assembly of the supporting frame and the rotating body;

[0035] Figure 12 A cross-sectional structural diagram showing the positioning of the set screw spherical surface and the conical hole of the rotating body.

[0036] Number in the diagram:

[0037] 1. Support frame; 2. Rotating body; 3. Set screw; 4. Workpiece; 5. Cover plate;

[0038] 101. Locking pin; 102. First column; 103. Second column; 104. Bearing hole; 105. Positioning hole; 106. Connecting hole; 201. U-shaped groove; 202. Fixing hole; 203. Base plate; 204. Vertical plate; 205. Central shaft; 206. Machining shaft; 207. Tapered hole. Detailed Implementation

[0039] To make the technical problems to be solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of this invention are described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0040] See Figures 3 to 12 This embodiment proposes a flexible processing device for internal trapezoidal threads with a large length-to-diameter ratio, including a support frame 1, a rotating body 2, and a set screw 3;

[0041] The support frame 1 includes a locking post 101 at the bottom, with a horizontal top. A first post 102 and a second post 103 are fixedly mounted on the top surface of the locking post 101, and the first post 102 and the second post 103 are parallel to each other. The first post 102 is provided with a bearing hole 104, and the second post 103 is provided with a positioning hole 105. The bearing hole 104 and the positioning hole 105 are coaxially arranged, and the radius of the bearing hole 104 is larger than the radius of the positioning hole 105. The second post 103 is provided with two connecting holes 106, which are symmetrically arranged vertically with the positioning hole 105 as the center. The locking post 101 is used for locking and fixing to the machine tool, and the bearing hole 104 and the positioning hole 105 are used to connect the rotating body 2.

[0042] In this embodiment, the support frame 1 is machined using a high-precision five-axis machining center to machine the φ47H7 bearing hole 104 and the φ16H7 positioning hole 105, ensuring that the coaxiality is no greater than 0.05. A thread is machined on one side of the φ47 bearing hole 104 to ensure that the rotating body 2 can pass through without interfering with the bearing. Simultaneously, a 2-M12 connecting hole 106 is machined on the end face of the φ16 positioning hole 105. The connecting hole 106 has an internal thread and is used to connect the set screw 3. The connecting hole 106 and the set screw 3 cooperate to fix the workpiece 4 and to repeat the positioning after rotating 180°. The structure of the workpiece 4 is shown in Figure 1 and... Figure 2 .

[0043] The rotating body 2 includes a U-shaped groove 201, which includes a base plate 203 and cylindrical vertical plates 204 on both sides of the base plate 203. The base plate 203 of the U-shaped groove 201 has fixing holes 202. The U-shaped groove 201 is fixedly connected to the workpiece 4 by bolts passing through the fixing holes 202, thus positioning the workpiece 4 with the U-shaped groove 201. A central shaft 205 is provided on the outer wall of the vertical plate 204 on one side of the base plate 203, and the central shaft 205 is used to connect with a bearing. A machining shaft 206 is provided on the outer wall of the vertical plate 204 on the other side of the base plate 203, and the machining shaft 206 is used to rotatably connect with the positioning hole 105. The central shaft 205 and the machining shaft 206 are coaxially arranged, and the outer diameter of the vertical plate 204 is adapted to the inner diameter of the bearing hole 104. Two tapered holes 207 are provided on the outer wall of the vertical plate 204 with the machining shaft 206, and the tapered holes 207 correspond to the connecting holes 106.

[0044] In use, the bottom of workpiece 4 is fixed to the fixing hole 202 of rotating body 2 with bolts. Then, workpiece 4, together with rotating body 2, is inserted into the first column 102 and the second column 103 of support frame 1 through bearing hole 104, so that tapered hole 207 corresponds to connecting hole 106. At the same time, machining shaft 206 extends into positioning hole 105, and the end of central shaft 205 is located outside the first column 102 and connected to bearing. Then, set screw 3 is screwed into connecting hole 106, so that the end of set screw 3 abuts against tapered hole 207. The end of set screw 3 is hemispherical. Utilizing the automatic centering and high repeatability of the spherical surface of set screw 3 with tapered hole 207, the thread coaxiality is ≤0.05 after workpiece 4 is rotated 180 degrees. When the workpiece 4 is being fed into the machine, the set screw 3 is connected to the rotating body 2 and the support frame 1. After the workpiece 4 is finished on one side, the set screw 3 is removed, and the rotating body 2 is rotated 180° together with the workpiece 4 through the bearing. Then the set screw 3 is screwed in.

[0045] To ensure the stability of workpiece 4, a pin hole 208 is provided at the top of the vertical plate 204, and a cover plate 5 is connected between the tops of the two vertical plates 204. The cover plate 5 is connected and fixed to the pin hole 208 by a positioning pin.

[0046] In this embodiment, the rotating body 2 employs a central shaft 205 with a turning dimension of φ47h6 and a machining shaft 206 with a dimension of φ16h6, ensuring that the coaxiality of the central shaft 205 and the machining shaft 206 is no greater than 0.05. Simultaneously, two 45° tapered holes 207 for positioning are machined on one side of the machining shaft 206, with an opening size of φ12.02H7 and a depth of 4mm. The positioning dimensions are consistent with the 2-M12 connecting holes 106 in the support frame 1. 2-M6 pin holes 208 are formed at the top, which are used to clamp the workpiece 4 via a cover plate 5.

[0047] This embodiment also proposes a flexible machining method for internal trapezoidal threads with a large length-to-diameter ratio, which uses the above-mentioned machining device and includes the following steps:

[0048] Step 1: Fix the workpiece 4 to the rotating body 2, then insert the rotating body 2 from the bearing hole 104 side of the support frame 1, press and fix it with the cover plate 5, and insert the set screw 3 to fix it again.

[0049] Step 2: Before formal machining, test cut the thread starting point to the center of rotation at an integer multiple of the pitch plus a correction value. Then start turning one side of the thread, adjusting the Z-axis coordinate system (0 ± correction value).

[0050] Step 3: After thread cutting on one side is complete, remove set screw 3. Rotate the bearing to rotate the rotating body 2 and workpiece 4 by 180°. After rotating 180°, adjust the phase angle to ensure that the two thread lines are evenly distributed on the circumference. Reinstall set screw 3 for repeated positioning and fixation. Begin thread cutting on the other side.

[0051] Phase angle (θ) = 360° / number of lines (n)

[0052] For double-ended threads (n=2)

[0053] Phase angle (θ) = 360° / 2 = 180°;

[0054] This invention enables part rotation and high repeatability positioning. With a single clamping and without tool removal (relative rotational relationship unchanged), it utilizes the automatic alignment and high repeatability of the spherical surface and tapered hole to achieve a thread coaxiality of ≤0.05 after the workpiece rotates 180 degrees. By utilizing the phase angle correspondence of the double-ended thread, the Z-axis origin is recalibrated to ensure accurate positional relationship between the new coordinate system and the workpiece, avoiding tool contact and ensuring effective engagement between the screw and the thread.

[0055] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features.

[0056] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0057] To provide the public with a thorough understanding of the present invention, specific details have been described in detail in the above preferred embodiments. However, those skilled in the art can fully understand the invention even without these detailed descriptions. Several improvements and modifications can be made without departing from the principles of the invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flexible machining device for internal trapezoidal threads with a large length-to-diameter ratio, characterized in that, The system includes a support frame (1), a rotating body (2), and a set screw (3). The bottom of the support frame (1) is connected to the machine tool. The support frame (1) is provided with a connecting groove for connecting the rotating body (2). The rotating body (2) is rotatably connected in the connecting groove. A connecting hole (106) is provided on one side of the connecting groove. The connecting hole (106) is used to connect the set screw (3). The rotating body (2) includes a U-shaped groove (201). The workpiece (4) is fixedly connected to the U-shaped groove (201). A tapered hole (207) is provided on one side of the outer wall of the U-shaped groove (201). The tapered hole (207) corresponds to the connecting hole (106). The end of the set screw (3) is hemispherical. The set screw (3) is screwed into the connecting hole (106) so that the end of the set screw (3) abuts against the tapered hole (207). The connection hole (106) and the set screw (3) cooperate to fix the workpiece (4) and to repeat the positioning of the workpiece (4) after rotating 180°.

2. The flexible machining device for large aspect ratio internal trapezoidal threads according to claim 1, characterized in that, The support frame (1) includes a locking post (101) at the bottom, which is used to lock and fix it to the machine tool.

3. The flexible machining device for large aspect ratio internal trapezoidal threads according to claim 2, characterized in that, The top of the locking post (101) is horizontal. A first post (102) and a second post (103) are fixedly installed on the top surface of the locking post (101). The first post (102) and the second post (103) are parallel to each other. The top surface of the locking post (101), the first post (102) and the second post (103) together form a connecting groove.

4. The flexible machining device for large aspect ratio internal trapezoidal threads according to claim 3, characterized in that, The first column (102) is provided with a bearing hole (104), and the second column (103) is provided with a positioning hole (105). The bearing hole (104) and the positioning hole (105) are coaxially arranged, and the radius of the bearing hole (104) is larger than the radius of the positioning hole (105). The second column (103) is provided with two connecting holes (106), and the two connecting holes (106) are symmetrically arranged vertically with the positioning hole (105) as the center.

5. The flexible machining device for large aspect ratio internal trapezoidal threads according to claim 4, characterized in that, The U-shaped channel (201) includes a base plate (203) and vertical plates (204) on both sides of the base plate (203); the outer diameter of the vertical plate (204) is adapted to the inner diameter of the bearing hole (104).

6. The flexible machining device for large aspect ratio internal trapezoidal threads according to claim 5, characterized in that, The base plate (203) is provided with fixing holes (202), and the U-shaped groove (201) is fixedly connected to the workpiece (4) by bolts passing through the fixing holes (202).

7. The flexible machining device for large aspect ratio internal trapezoidal threads according to claim 5, characterized in that, A central shaft (205) is provided on the outer wall of the vertical plate (204) on one side of the base plate (203), and the central shaft (205) is used to connect with the bearing; a machining shaft (206) is provided on the outer wall of the vertical plate (204) on the other side of the base plate (203), and the machining shaft (206) is used to rotatably connect with the positioning hole (105); the central shaft (205) and the machining shaft (206) are coaxially arranged.

8. The flexible machining device for large length-to-diameter ratio internal trapezoidal threads according to claim 5, characterized in that, The top of the vertical plate (204) is provided with a pin hole (208), and a cover plate (5) is connected between the tops of the two vertical plates (204). The cover plate (5) is fixed to the pin hole (208) by a positioning pin.

9. A flexible machining method for internal trapezoidal threads with a large length-to-diameter ratio, characterized in that, The method employs a flexible machining apparatus for large aspect ratio internal trapezoidal threads as described in any one of claims 1-8, and includes the following steps: Step 1: Fix the workpiece (4) and the rotating body (2), then put the rotating body (2) into the connecting groove of the support frame (1), and put in the set screw (3) so that the end of the set screw (3) abuts against the tapered hole (207) to achieve repeated positioning; Step 2: Begin turning the thread on one side of the workpiece (4); Step 3: After the thread cutting on one side is completed, remove the set screw (3) and rotate the rotating body (2) and the workpiece (4) by 180°. After rotating by 180°, adjust the phase angle to ensure that the two thread lines are evenly distributed on the circumference. Then, reinstall the set screw (3) for repeated positioning and fixation, and start cutting the thread on the other side of the workpiece (4).

10. A flexible machining method for internal trapezoidal threads with a large length-to-diameter ratio according to claim 9, characterized in that, Before formal machining, the starting point of the trial thread cut should be an integer multiple of the pitch plus a correction value, from the center of rotation.

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