A high volume fraction aluminum-based silicon carbide small hole thread processing technology

Abstract

The invention discloses a high volume fraction aluminum-based silicon carbide small hole thread processing process, the steps of which are thread milling interference mechanism analysis, thread milling cutter tooth profile optimization design, thread milling cutter material selection, tool measurement, bottom hole confirmation, thread milling, and successively using a measuring rod to detect the minor diameter of the threaded hole and using a go / no-go gauge to detect the standard thread; using the process of the invention, tool wear is reduced compared with the original process, and the cost is reduced by at least half.

Description

Technical Field

[0001] The invention relates to the technical field of advanced composite material processing, and in particular to a processing technology for small hole threads of high volume fraction aluminum-based silicon carbide materials. Background Art

[0002] Small hole threads are widely used in precision instruments and other parts, and have application value in aerospace. The current problems in the processing of small hole threads in 60% SiCp / Al composite materials are mainly the difficulties of large tapping torque, difficult chip removal, easy breakage of taps, and technical problems such as flexible production to adapt to small batches of small hole thread milling of multiple varieties.

[0003] At present, the main method for small hole thread processing of 60% SiCp / Al composite materials is to adjust the geometric angle of the tap, thereby reducing the contact between the back tool face and the machined surface, achieving the effect of reducing torque during tapping.

[0004] After tap trimming, the sharpness is improved, but the tool wear is accelerated, resulting in a single tap being unable to complete the processing of a threaded hole in the composite material with this volume fraction. Summary of the invention

[0005] The purpose of the present invention is to provide a typical process method for milling commonly used standard threads of 60% SiCp / Al composite materials to meet the performance requirements of small threads, improve the quality and efficiency of processing, and reduce processing costs.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a high volume fraction aluminum-based silicon carbide small hole thread processing process, comprising the following steps: Step 1, select a thread milling cutter with a blade pitch of 0.5 mm, a length L of 3 mm, a tooth height H of 0.3 mm, a tooth top and root fillet r of 0.05, a blade rake angle of 0°, and a back angle of 5°; Step 2, drilling 200 M2.5 threaded bottom holes on the 60% SiCp / Al composite workpiece; Step 3, accurately measure the initial diameter of the thread milling cutter on the tool setting instrument and take a photo to record the shape of the thread milling cutter edge; Step 4, bottom hole confirmation: self-check whether the bottom hole diameter on the 60% SiCp / Al composite workpiece meets the requirements of GB / T196-2003 basic size standard for common threads or GJB119.3A-2015 related requirements for internal threads for installing wire thread inserts; Step 5, thread milling: when the thread depth is 1.5 times the diameter, the linear speed Vc is 25-30 m / min, the feed speed F is 0.03-0.06 mm / rev, and the side cutting width Ae is 0.05 mm; when the thread depth is 2-2.5 times the diameter, the linear speed Vc is 20-25 m / min, the feed speed F and the side cutting width Ae remain unchanged; when the thread depth is 3 times the diameter, the linear speed Vc is 15-20 m / min, the feed speed F is 0.03-0.06 mm / rev, and the side cutting width Ae is 0.03 mm; Step 6, inspection: Use a measuring rod of corresponding diameter to measure the minor diameter of the threaded hole to meet the requirements of GB / T196-2003 basic dimension standard for common threads or GJB119.3A-2015 related requirements for internal threads for installing wire thread inserts; Step 7, Inspection: Use a go / no-go gauge to inspect standard threads or internal threads for installing wire thread inserts.

[0007] Furthermore, the thread milling cutter uses a double-sided blade that can be used on both sides, and the left and right teeth are offset by 0.5P in the Z direction.

[0008] Furthermore, a PCD thread milling cutter made of diamond material is selected for internal thread milling.

[0009] Furthermore, the steps between step 4 and step 5 also include: Thread milling cutter wear test: Use a tool setting instrument to accurately measure the tool diameter and record the diameter; Confirm the wear of the thread milling cutter: Calculate the wear by comparing the thread milling cutter diameter with the initial diameter; Detect the radius of the thread milling cutter tip: Use a tool setting instrument to detect the radius of the thread milling cutter. If the radius is greater than P / 5, the wear limit of the tool radius has been reached, which is the processing limit of the thread milling cutter.

[0010] Furthermore, when inspecting ordinary threads, the through end of the go / no-go gauge should be screwed into and passed through the internal thread of the workpiece, and the stop end should be screwed into the threaded parts at both ends of the internal thread of the workpiece. The amount of screwing should not exceed 2 pitches to ensure the effective thread depth requirements.

[0011] Furthermore, when inspecting and installing the internal thread of the wire thread insert, the through end of the go / no-go gauge should be screwed into and passed through the internal thread of the workpiece, and the stop end should be screwed into the threaded parts at both ends of the internal thread of the workpiece. The screwing amount should not exceed 2 pitches, and the effective thread depth should be the actual working length in accordance with the standard requirements of GB / T24425.2-2009 for ordinary blind hole wire thread inserts plus 3 times the pitch.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: through testing and analysis of tool wear and threaded hole performance under the process forming method, the present invention uses an M2.5 specification thread milling tool to perform thread milling verification. A single thread milling tool can normally mill 120 threaded holes, and tool wear is reduced compared to the original process, and the cost is reduced by at least half. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of a thread milling cutter of the present invention; Figure 2 The small hole thread of the 60% SiCp / Al composite material processed by the present invention; Figure 3 is the initial diameter and profile of the thread milling cutter; Figure 4 The diameter and tool tip radius of the thread milling cutter after processing; Figure 5 This is the PCD thread milling cutter used in the present invention. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and implementation cases. Example 1

[0015] The invention discloses a high volume fraction aluminum-based silicon carbide small hole thread processing process, which comprises the following steps.

[0016] Step 1: Analysis of thread milling interference mechanism.

[0017] When machining threads, the tooth angle of the internal thread turned by a turning tool with an angle of 60° on both sides is 60°, and the thread thickness is also correct in theory, but it is different for milling threads. When the axial section of the thread milling cutter teeth is the same as the axial section of the standard thread profile, when milling threads, at a certain instantaneous position, whether it is forward milling or reverse milling, as long as there is a helix angle, it will interfere with the thread. This situation exists at the instantaneous position of each circle when using a thread milling cutter. As a result, the axial tooth angle of the thread is reduced and the tooth thickness is narrower than expected.

[0018] Since the small hole thread pressing of the 60% SiCp / Al composite workpiece is narrow and thin, it is easy to cause the tooth profile to break during actual processing, which eventually leads to the small diameter out of tolerance.

[0019] Optimized design of thread milling cutter tooth profile: The present invention further designs the thread milling cutter blade, wherein the blade pitch is 0.5mm, the length L is 3mm, the tooth height H is 0.3mm, and the tooth top and tooth root fillet r0.05. The blade rake angle is 0° and the back angle is 5°. The blade is a double-sided blade, and the left and right tooth positions are offset by 0.5P in the Z direction, and both sides can be used. The main dimensions of the thread milling cutter blade are as follows: Figure 1 shown.

[0020] Step 2, drill 200 M2.5 threaded bottom holes on the 60% SiCp / Al composite workpiece.

[0021] Step 3, thread milling cutter material selection: According to the physical properties analysis of different types of tool materials, diamond is generally used as the material of the milling cutter in the internal thread milling process.

[0022] Step 4: Tool measurement to confirm the initial wear of the thread milling cutter: accurately measure the initial diameter of the thread milling cutter on the tool setting instrument and take a photo to record the shape of the thread milling cutter edge. Figure 3 shown.

[0023] Step 5, bottom hole confirmation: self-check whether the bottom hole diameter on the workpiece meets the requirements of GB / T196-2003 basic size standard for common threads or GJB119.3A-2015 related requirements for internal threads for installing wire thread inserts.

[0024] Step 6, thread milling: Use thread milling cutter of corresponding specifications and adopt thread milling method.

[0025] When the thread depth is 1.5 times the diameter, the linear speed Vc is 25-30 m / min, the feed speed F is 0.03-0.06 mm / rev, and the side cutting width Ae is 0.05 mm.

[0026] When the thread depth is 2 to 2.5 times the diameter, the linear speed Vc is 20 to 25 m / min, the feed speed F and the side cutting width Ae remain unchanged.

[0027] When the thread depth is 3 times the diameter, the linear speed Vc is 15-20 m / min, the feed speed F is 0.03-0.06 mm / rev, and the side cutting width Ae is 0.03 mm.

[0028] Step 7, Inspection: Use a measuring rod of corresponding diameter to measure the minor diameter of the threaded hole, which should meet the requirements of GB / T196-2003 basic dimension standard for common threads or GJB119.3A-2015 related requirements for internal threads for installing wire thread inserts.

[0029] Step 8, Inspection: Ordinary standard threads are inspected using go and stop gauges of corresponding specifications. The go end should be screwed into the internal thread of the workpiece, and the stop end should be screwed into the threaded parts at both ends of the internal thread of the workpiece. The screwing amount should not exceed 2 pitches to ensure the effective thread depth requirements.

[0030] Step 9, Inspection: The thread of the wire thread insert is inspected with a special bottom hole internal thread gauge for the wire thread insert. The through end should be screwed into the internal thread of the workpiece, and the stop end should be screwed into the threaded parts at both ends of the internal thread of the workpiece. The screwing amount should not exceed 2 pitches, and the effective thread depth should meet the actual working length in accordance with the standard requirements of GB / T24425.2-2009 for ordinary blind hole wire thread inserts plus 3 times the pitch.

[0031] Repeat the above steps to test the number of threaded holes milled under extreme tool wear. Figure 5 shown. Example 2

[0032] The difference of this embodiment is that: between step 4 and step 5, the following is also included: Thread milling cutter wear test: Use a tool setting probe to accurately measure the tool diameter and record the diameter.

[0033] Confirm thread milling cutter wear: Calculate the wear by comparing the thread milling cutter diameter with the initial diameter.

[0034] Detect the radius of the thread milling cutter tip: Use a tool setting instrument to detect the radius of the thread milling cutter tip, such as Figure 4 As shown, if the radius>P / 5, the wear limit of the tool radius is reached, which is the processing limit of the thread milling cutter.

[0035] The above embodiments are only illustrative of the principles and effects of the present invention, as well as some embodiments of its application. For those skilled in the art, several modifications and improvements may be made without departing from the creative concept of the present invention, and all of these belong to the protection scope of the present invention.

Claims

1. A high volume fraction aluminum-based silicon carbide small hole thread processing process, characterized in that: The steps include: Step 1, select a thread milling cutter with a blade pitch of 0.5mm, a length of 3mm, a tooth height of 0.3mm, a tooth top and root fillet of 0.05, a blade rake angle of 0°, and a back angle of 5°; Step 2, drilling a threaded bottom hole on the 60% SiCp / Al composite workpiece; Step 3, accurately measure the initial diameter of the thread milling cutter on the tool setting instrument and take a photo to record the shape of the thread milling cutter edge; Step 4, self-check the bottom hole diameter on the workpiece to meet the basic size requirements of ordinary threads or the internal thread requirements for installing wire thread sleeves; Step 5, thread milling: when the thread depth is 1.5 times the diameter, select a linear speed of 25-30 m / min, a feed speed of 0.03-0.06 mm / rev and a side cutting width of 0.05 mm; when the thread depth is 2-2.5 times the diameter, select a linear speed of 20-25 m / min, keeping the feed speed and side cutting width unchanged; when the thread depth is 3 times the diameter, select a linear speed of 15-20 m / min, a feed speed of 0.03-0.06 mm / rev and a side cutting width of 0.03 mm; Step 6, using a measuring rod to measure the minor diameter of the threaded hole to meet the basic size requirements of ordinary threads or the internal thread requirements for installing wire thread sleeves; Step 7: Use a go / no-go gauge to check the standard thread or the internal thread for installing the wire thread insert.

2. A high volume fraction aluminum-based silicon carbide small hole thread processing process according to claim 1, characterized in that: The thread milling cutter uses a double-sided blade that can be used on both sides, and the left and right teeth are offset by 0.5P in the Z direction.

3. A high volume fraction aluminum-based silicon carbide small hole thread processing process according to claim 2, characterized in that: When milling internal threads, choose a PCD thread milling cutter made of diamond material.

4. A high volume fraction aluminum-based silicon carbide small hole thread processing process according to claim 1, 2 or 3, characterized in that: The steps between step 5 and step 6 also include: using a tool setting instrument to accurately measure the tool diameter and record the diameter; calculating the wear amount by comparing the thread milling cutter diameter with the initial diameter; using a tool setting instrument to detect the thread milling cutter corner radius, if the corner radius is greater than P / 5, the wear limit of the tool corner radius has been reached.

5. A high volume fraction aluminum-based silicon carbide small hole thread processing process according to claim 4, characterized in that: When testing ordinary threads, the through end of the go / no-go gauge is screwed into the internal thread of the workpiece, and the stop end is screwed into the threaded parts at both ends of the internal thread of the workpiece. The amount of screwing should not exceed 2 pitches.

6. A high volume fraction aluminum-based silicon carbide small hole thread processing process according to claim 4, characterized in that: When inspecting and installing the internal thread of the wire thread insert, the through end of the through and stop gauge is screwed into the internal thread of the workpiece, and the stop end is screwed into the threaded parts at both ends of the internal thread of the workpiece. The screwing amount should not exceed 2 pitches, and the effective thread depth is the actual working length that meets the standard requirements plus 3 times the pitch.

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