Machining method for reversely scraping threaded hole and combined reverse scraping tool

Abstract

The invention discloses a machining method for reversely scraping a threaded hole and a combined reverse scraping cutter, rough machining, finish machining, boss forming and thread scraping of a bottom hole are completed step by step through four special cutters, and the problems that in the prior art, cutters are scarce, the machining precision is low, and the space is limited are solved. The method is particularly suitable for a narrow inner cavity environment, and efficient and high-precision forming of the M16 * 0.5-LH threads can be achieved.

Description

Technical Field

[0001] The present invention belongs to the field of mechanical technology, and particularly relates to a processing method for reverse scraping threaded holes and a combined reverse scraping tool. Background Art

[0002] Disadvantages of existing reverse scraping tools: Currently, reverse scraping threaded hole tools are less applied. Most reverse scraping tools are used for the processing of counterbores. At present, the processing of reverse threaded holes is relatively difficult. The method of using a spindle adapter to process threaded holes has a high cost, and special tools are required for the processing of threaded holes. The volume of the inner cavity of the housing is small, and the shank of the adapter cannot achieve deep processing. The processing is time-consuming and laborious, and it is impossible to guarantee the processing accuracy of the threaded holes. Therefore, there are difficulties in pitch control, feed, and retraction during the processing of reverse threaded holes. The tooth profile is easily damaged after processing the reverse threaded hole, and the processing accuracy is relatively low. The effective thread length of the reverse threaded hole directly affects the rigidity of the tool.

[0003] Chinese invention with publication number CN101543963B discloses a reverse scraping tool shank structure, including a tool shank and a magnetic chuck drill spindle. The tool shank is inserted into the magnetic chuck drill spindle and fixedly connected. A shank with a Morse taper is inserted into the spindle hole of the magnetic chuck drill. To prevent the shank from disengaging from the magnetic chuck drill spindle during reverse scraping, a thread is designed on the shank, and the thread sleeve is fixed to the magnetic chuck drill spindle with screws, so that the scraping tool rotates together with the spindle. The closing part of the shank is designed in a special structural form, which not only makes it convenient to load and unload the cutting reverse scraping force tool, but also can drive the tool to perform reverse scraping cutting in the processing area, thus meeting the requirements of high-efficiency production processing. However, it is still impossible to process products with special structures. For example, when processing threaded holes on the inner cavity arm of a square housing, as Figure 1 shown, such reverse threaded holes (such as M16×0.5) are usually located deep inside the housing cavity. Currently, reverse scraping threaded hole processing tools on the market cannot meet the processing requirements of threaded holes on the inner cavity arm, and the cost of reverse scraping tools is relatively high. Moreover, they are applicable to some conventional reverse counterbore processing, and it is difficult to process reverse threaded holes of non-standard parts. Summary of the Invention

[0004] In order to solve the above problems, the present invention aims to provide a processing method for reverse scraping threaded holes and a combined reverse scraping tool.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A combined reverse scraping tool includes four sets of tools with the same tool shank diameter. The tool heads of the first tool and the second tool have the same structure. A convex platform is provided on the tool head of the third tool, and the tool head of the fourth tool is a thread milling cutter.

[0006] Furthermore, the height of the tool head of the second tool is less than that of the first tool head, and the diameter of the tool head of the second tool is greater than that of the first tool.

[0007] Furthermore, the first tool and the second tool include a main cutting edge and a secondary cutting edge perpendicular to the main cutting edge.

[0008] Furthermore, the bottom surface of the third tool boss is the main cutting edge, and the side surface is the secondary cutting edge. The conical surface of the fourth tool is the main cutting edge.

[0009] A processing method for reverse scraping threaded holes includes the following steps:

[0010] Step 1: Use the first tool to perform reverse rough machining on the threaded bottom hole;

[0011] Step 2: Use the second tool to perform reverse finish machining on the threaded bottom hole;

[0012] Step 3: Use the third tool to machine a reverse annular groove at the bottom of the threaded bottom hole;

[0013] Step 4: Use the fourth tool to perform reverse threading on the threaded bottom hole.

[0014] Furthermore, specifically for Step 1, the tool shank of the first tool passes through the through hole of the part, the tool retreats and contacts the end face of the part, the main cutting edge deeply processes the part, and then the secondary cutting edge cooperates with the main cutting edge to rotate bidirectionally and cut in for hole opening.

[0015] Furthermore, the finish machining method in Step 2 is the same as the machining method in Step 1. Compared with rough machining, the machining size reaches the required size in finish machining.

[0016] Furthermore, specifically for Step 3, after the second tool finishes machining the threaded bottom hole and withdraws, the third tool penetrates into the threaded bottom hole. The main cutting edge of the boss contacts and deeply grooves the bottom surface of the bottom hole, and then the secondary cutting edge cooperates with the main cutting edge to rotate bidirectionally and cut in to machine an annular groove.

[0017] Furthermore, specifically for Step 4, after the third tool withdraws, the fourth tool enters the threaded bottom hole to perform threading on the threaded bottom hole.

[0018] Furthermore, the processed shape of the part meets the requirements, and the internal thread dimension accuracy is high.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. Through the combination of four special tools, the present invention realizes the full-process forming machining from the bottom hole to the thread, solving the problems of scattered processes and out-of-control accuracy in the prior art.

[0021] 2. The present invention has low cost and high efficiency. The integral tool design does not rely on expensive adapters, is suitable for small inner cavity machining, reduces the number of clamping times, and improves the machining efficiency.

[0022] 3. The precision of the present invention is reliable. The bottom hole size, boss shape, and thread parameters are controlled in stages, effectively avoiding thread damage and ensuring thread precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following-described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0024] Figure 1 Schematic diagram of the reverse threaded hole in the inner cavity of the square housing of the present invention;

[0025] Figure 2 Schematic diagram of the structure of the first tool of the present invention;

[0026] Figure 3 Schematic diagram of the structure of the second tool of the present invention;

[0027] Figure 4 Schematic diagram of the structure of the third tool of the present invention;

[0028] Figure 5 Schematic diagram of the structure of the fourth tool of the present invention;

[0029] In the figure, 1 - the first tool; 2 - the second tool; 3 - the third tool; 4 - the fourth tool; A - the main cutting edge; B - the secondary cutting edge. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following further describes the present invention in conjunction with the drawings and specific embodiments. However, it should not be understood that the scope of the subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, all modifications, substitutions, and changes made according to common general knowledge and customary means in the art are included in the scope of the present invention.

[0031] Refer to Figure 1 , it is required to machine an M16×0.5 threaded hole. Four tools are designed to cooperate and are processed according to a special processing sequence to solve the problem of machining the internal cavity threaded hole.

[0032] Refer to Figure 2 The first tool 1 is an integral molding structure, which is used for reverse rough machining of the threaded bottom hole to Φ15mm. The tool head is provided with a main cutting edge A and a secondary cutting edge B. The main cutting edge A and the secondary cutting edge B are designed perpendicular to each other and can rotate bidirectionally to cut into the hole. The height of the tool head is 10mm, and the radius is 15 ± 0.02mm.

[0033] Refer to Figure 3It is the second tool 2, which is a finishing reverse facing tool, used to finish the bottom hole to Φ15.5mm in reverse to improve the accuracy of the bottom hole. The height of the tool tip is 5mm, and the radius is 15.5±0.02mm.

[0034] Refer to Figure 4 It is the third tool 3, a reverse facing annular groove tool. The tool tip is provided with a convex platform structure. The bottom surface is the main cutting edge A, and the side surface is the secondary cutting edge B, used to machine the reverse annular groove at the bottom of the threaded hole. The height of the bottom plate of the tool tip is 4mm, the diameter is about 14.6mm, the height of the convex platform is 3mm, and the radius is about 10.5mm.

[0035] Refer to Figure 5 It is the fourth tool 4, a reverse facing thread milling cutter. The tool tip is a thread milling cutter structure, and the conical surface is the main cutting edge, used to machine the M16×0.5 threaded hole in reverse.

[0036] The processing method is as follows:

[0037] Step 1: Rough machining: The first tool 1 rotates and cuts in, and the main and secondary cutting edges cooperate to scrape the bottom hole to Φ15mm;

[0038] Step 2: Finishing: The second tool 2 trims the bottom hole to Φ15.5mm along the same path;

[0039] Step 3: Annular groove machining: The main cutting edge of the third tool 3 contacts the bottom of the hole, and the secondary cutting edge cuts in radially to form an annular groove;

[0040] Step 4: Thread forming: The fourth tool 4 scrapes and forms the M16×0.5-LH thread along a spiral path.

[0041] By using the above method, the accuracy is improved, the bottom hole error and the thread pitch error are controlled in stages during processing, the cost is reduced, the tool set is designed in a standardized manner, the tool change time is reduced, the efficiency is improved, and the applicability is enhanced: it is adapted to the narrow and straight inner cavity space, and the effective length of the thread is increased.

[0042] The present invention mainly adopts an integral forming reverse facing tool design. From the rough machining and finishing of the threaded bottom hole, the machining of the convex platform of the threaded hole, and the machining of the threaded hole, 4 special reverse facing tools are designed, and finally the forming machining of the reverse facing threaded hole is completed. The reverse facing forming machining method of the threaded hole is realized, providing a reference for promoting the reverse facing machining of the threaded hole.

[0043] The above has introduced in detail a processing method for reverse scraping threaded holes and a combined reverse scraping tool provided by the present invention. Specific examples are used in this article to elaborate on the structure and working principle of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A combined reverse scraping tool, characterized in that: It includes four sets of cutting tools with consistent shank diameters. The cutting head structures of the first cutting tool (1) and the second cutting tool (2) are the same. A boss is provided on the cutting head of the third cutting tool (3), and the cutting head of the fourth cutting tool (4) is a thread milling cutter.

2. The combined reverse scraping tool according to claim 1, characterized in that: The height of the cutting head of the second cutting tool (2) is less than that of the first cutting head (1), and the diameter of the cutting head of the second cutting tool (2) is greater than that of the first cutting tool (1).

3. The combined reverse scraping tool according to claim 1, characterized in that: The first cutting tool (1) and the second cutting tool (2) include a main cutting edge and a sub-cutting edge perpendicular to the main cutting edge.

4. The combined reverse scraping tool according to claim 1, characterized in that: The bottom surface of the boss of the third cutting tool (3) is the main cutting edge, and the side surface is the sub-cutting edge. The conical surface of the fourth cutting tool (4) is the main cutting edge.

5. A machining method for reverse scraping a threaded hole using the combination reverse scraping tool according to any one of claims 1-4, characterized in that: It includes the following steps Step 1: Use the first cutting tool (1) to perform reverse rough machining on the thread bottom hole; Step 2: Use the second cutting tool (2) to perform reverse finish machining on the thread bottom hole; Step 3: Use the third cutting tool (3) to machine a reverse annular groove at the bottom of the thread bottom hole; Step 4: Use the fourth cutting tool (4) to perform reverse threading on the thread bottom hole.

6. The machining method of the reverse scraping threaded hole according to claim 5, characterized in that: Specifically, for Step 1, the shank of the first cutting tool (1) passes through the through hole of the part, the tool retracts and contacts the end face of the part, the main cutting edge deeply processes the part, and then the sub-cutting edge cooperates with the main cutting edge to rotate bidirectionally and cut in for hole opening.

7. The machining method of the reverse scraping threaded hole according to claim 5, characterized in that: The finish machining method in Step 2 is the same as the machining method in Step 1. Compared with rough machining, the machining size in finish machining reaches the required size.

8. The machining method of the reverse scraping threaded hole according to claim 5, characterized in that: Specifically, for Step 3, after the second cutting tool (2) finishes machining the thread bottom hole and withdraws, the third cutting tool (3) penetrates into the thread bottom hole. The main cutting edge of the boss contacts the bottom surface of the bottom hole and deeply grooves, and then the sub-cutting edge cooperates with the main cutting edge to rotate bidirectionally and cut in to machine an annular groove.

9. The machining method of the reverse scraping threaded hole according to claim 5, characterized in that: Specifically, for Step 4, after the third cutting tool (4) withdraws, the fourth cutting tool (4) enters the thread bottom hole and performs threading on the thread bottom hole.

10. The machining method of the reverse scraping threaded hole according to claim 5, characterized in that: The processed shape and internal thread dimensions of the part meet the requirements.

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