A method for preventing chip entanglement in high-strength structural steel rotating parts

Abstract

This invention belongs to the field of machining, specifically relating to a method for preventing chip entanglement in the machining of high-strength structural steel rotating parts. When chip entanglement occurs, operators use hooks or pliers to remove the chips before further processing, reducing equipment efficiency, wasting production capacity, and negatively impacting product surface quality. This invention machines helical grooves with a pitch of 1.5mm and a depth of 0.1–0.3mm, flattening the grooves with a feed rate of 0.2mm / r ≤ F ≤ 0.3mm / r until a machining allowance of 0.13mm is achieved. For machining helical grooves with a pitch of 3mm and a depth of 0.1mm, the machining parameters are: rotational speed S: 200r / min, feed rate F: 3mm / r, and depth of cut 0.1mm. The part blank diameter is then machined to the final size with the following parameters: rotational speed S: 1500r / min, feed rate F: 0.05mm / r, and depth of cut 0.03mm. This invention solves the chip entanglement problem during the turning of rotary parts, enabling roughing and finishing of parts without human intervention. This not only improves the machining efficiency of parts but also meets the machining accuracy requirements.

Description

Technical Field

[0001] This invention belongs to the field of machining, specifically relating to a method for preventing chip entanglement in high-strength structural steel rotating parts. Background Technology

[0002] Helicopter rotor systems utilize a large number of high-strength bolts. As fasteners in the rotor system, these bolts need to withstand high-frequency, low-stress-amplitude cyclic loads, requiring extremely high strength and fatigue life. The material for these bolts is mostly high-strength structural steel 35Cr2Ni4MoA, with a heat-treated strength requirement of σb = 1230–1380 MPa (HRC 39.5-44). After heat treatment, this material exhibits high strength and good toughness, but it is not prone to chip breakage during machining. The resulting chips easily become entangled in the cutting tool or parts, leading to surface scratches and compromising dimensional accuracy.

[0003] The previous method for handling chip entanglement was to pause the program and stop the machine after chip entanglement occurred, and then have the operator use an iron hook or pliers to clean up the chips before proceeding with subsequent processing. This method cannot solve the chip entanglement problem at its root. Frequent shutdowns reduce the operating efficiency of the equipment and cause huge waste of production capacity. In addition, pausing the program and then restarting it will leave obvious tool marks on the surface of the parts, which is not conducive to ensuring the surface quality of the products. Summary of the Invention

[0004] The purpose of this invention is to propose a stable, reliable, and easy-to-implement method for preventing chip entanglement in high-strength structural steel rotating parts.

[0005] The technical solution of this invention provides a method for preventing chip entanglement in the machining of high-strength structural steel rotating parts, used for changing the diameter of the part blank. This method includes the following steps:

[0006] S1. Clamp the part blank on a CNC horizontal lathe;

[0007] S2. Select a CNC external turning tool holder with a tool rake angle of 93° or 95°, install a D-type carbide external turning insert with a tool tip radius of R0.4, and turn a spiral groove with a pitch of 1.5mm and a depth of 0.1~0.3mm. The machining parameters are: rotational speed S: 600r / min, feed rate F: 1.5mm / r;

[0008] S3. Using the same tool as S2, flatten the spiral groove, with a cutting feed rate of 0.2mm / r ≤ F ≤ 0.3mm / r;

[0009] S4. Repeat S2 and S3 until the machining allowance is 0.13mm;

[0010] S5. Using the same tool as S2, turn a spiral groove with a pitch of 3mm and a depth of 0.1mm. The machining parameters are: spindle speed S: 200r / min, feed rate F: 3mm / r, and depth of cut 0.1mm.

[0011] S6. Select a CNC external turning tool holder with a tool rake angle of 95° or 103.5°, install a V-type carbide external turning insert with a tool tip radius of R0.4, and machine the workpiece blank diameter to the final size. The machining parameters are: spindle speed S: 1500 r / min, feed rate F: 0.05 mm / r, and depth of cut 0.03 mm.

[0012] Advantageously, in S1, the part blank is mounted on a CNC horizontal lathe by clamping it at the head with a three-jaw chuck and tightening it at the tailstock.

[0013] Advantageously, the clamping size is not less than Φ12×10mm, and an A1.5 center hole is made at the tail of the part blank.

[0014] Advantageously, in S2, a spiral groove with a depth of 0.1 mm is machined in a single operation, while a spiral groove with a cutting depth of 0.3 mm is machined in two operations, with the first operation having a cutting depth of 0.2 mm and the second operation having a cutting depth of 0.1 mm.

[0015] Advantageously, in S3, the cutting parameters are: rotational speed S: 750 r / min, feed rate F: 0.27 mm / r, and the depth of cut is the same as the depth of the spiral groove, which is completed in a single cut.

[0016] Advantageously, the diameter of the blank rod of the part ranges from Φ6mm to Φ50mm, and the length-to-diameter ratio of the machining area is not greater than 10.

[0017] Advantageously, the heat-treated strength range of the part blank is 980 MPa ≤ σ b ≤1960Mpa.

[0018] Advantageously, the runout of the outer diameter of the blank is no more than 0.03 mm, and the straightness of the blank is no more than 0.03 mm, i.e., the equal height of the center of the spindle and the tailstock.

[0019] When the depth of cut exceeds 0.3mm in a single pass, the cutting tool will cause chip entanglement after passing on the surface of the part 2-3 times. The processing parameters provided in this invention can interrupt the originally continuous chip strips, forming broken chips, which are then thrown out by the centrifugal force generated by the rotation of the spindle.

[0020] The beneficial effects of this invention are as follows: This invention solves the problem of chip entanglement during the turning of rotary parts, enabling parts to complete rough and finish machining without human intervention, which not only improves the machining efficiency of parts, but also meets the machining accuracy requirements of parts. Detailed Implementation

[0021] The disclosed examples are described more fully, and some (but not all) of the disclosed examples are shown. In fact, many different examples may be described and these examples should not be construed as limited to those set forth herein. Rather, these examples are described so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0022] In one embodiment, high-strength structural steel bolts need to be manufactured. The shank of the bolt blank must first be machined to ensure its diameter meets the dimensional requirements before thread machining. The solution of this invention can ensure timely chip breaking and prevent chip entanglement during this process. The specific implementation process is as follows:

[0023] Step 1: Clamp the head of the bolt blank with a three-jaw chuck and tighten the tail of the bolt blank with a tailstock. Mount the bolt blank on a CNC horizontal lathe. The clamping size should be no less than Φ12×10mm. Make an A1.5 center hole at the tail of the bolt blank.

[0024] Step 2: Select a CNC external turning tool holder with a rake angle of 93° or 95°, and install a D-type carbide external turning insert with a tip radius of R0.4. Turn a helical groove with a pitch of 1.5mm and a depth of 0.3mm. The machining parameters are: spindle speed S: 600r / min, feed rate F: 1.5mm / r, and depth of cut 0.3mm. The machining is completed in two steps: the first cutting depth is 0.2mm, and the second cutting depth is 0.1mm.

[0025] Step 3: Using the same tool as in Step 2, flatten the spiral groove. Cutting parameters: spindle speed S: 750 r / min, feed rate F: 0.27 mm / r, depth of cut is the same as the spiral groove depth, and the cutting is completed in one pass.

[0026] Step 4: Repeat steps 2 and 3 until the machining allowance is 0.13mm;

[0027] Step 5: Using the same external turning tool as in Step 2, turn a spiral groove with a pitch of 3mm and a depth of 0.1mm. The machining parameters are: rotational speed S: 200r / min, feed rate F: 3mm / r, depth of cut 0.1mm, and ensure a finishing allowance of 0.03mm.

[0028] Step 6: Select a CNC external turning tool holder with a rake angle of 95° or 103.5°, and install a V-type carbide external turning insert with a tip radius of R0.4. Machin the bolt blank to the final size. The machining parameters are: spindle speed S: 1500 r / min, feed rate F: 0.05 mm / r, and depth of cut 0.03 mm.

[0029] The various examples of systems, apparatuses, and methods disclosed herein include a wide range of components, features, and functions. It should be understood that the various examples of systems, apparatuses, and methods disclosed herein may include any of the components, features, and functions of any of the other examples of systems, apparatuses, and methods disclosed herein in any combination or sub-combination, and all such possibilities are intended to fall within the scope of the invention.

[0030] Descriptions of various advantageous arrangements have been shown for illustrative and descriptive purposes, but such descriptions are not intended to be exclusive or limited to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. Furthermore, different advantageous examples may describe different advantages compared to other advantageous examples. One or more examples have been selected and described in order to best illustrate the principles and practical application of the examples, and to enable those skilled in the art to understand that this disclosure contains various examples with various modifications suitable for the particular intended use.

Claims

1. A method for preventing chip entanglement in the machining of high-strength structural steel rotating parts, used for machining the diameter of part blanks, characterized in that: This method includes the following: S1. Clamp the part blank on a CNC horizontal lathe; S2. Select a CNC external turning tool holder with a tool rake angle of 93° or 95°, install a D-type carbide external turning insert with a tool tip radius of R0.4, and turn a spiral groove with a pitch of 1.5mm and a depth of 0.1~0.3mm. The machining parameters are: rotational speed S: 600r / min, feed rate F: 1.5mm / r; S3. Using the same tool as S2, flatten the spiral groove, with a cutting feed rate of 0.2mm / r ≤ F ≤ 0.3mm / r; S4. Repeat S2 and S3 until the machining allowance is 0.13mm; S5. Using the same tool as S2, turn a spiral groove with a pitch of 3mm and a depth of 0.1mm. The machining parameters are: spindle speed S: 200r / min, feed rate F: 3mm / r, and depth of cut 0.1mm. S6. Select a CNC external turning tool holder with a tool rake angle of 95° or 103.5°, install a V-type carbide external turning insert with a tool tip radius of R0.4, and machine the workpiece blank diameter to the final size. The machining parameters are: spindle speed S: 1500 r / min, feed rate F: 0.05 mm / r, and depth of cut 0.03 mm.

2. The method for preventing chip entanglement in high-strength structural steel rotating parts according to claim 1, characterized in that: In S1, the part blank is clamped at the head by a three-jaw chuck and at the tail by a tailstock clamping method, thus mounting the part blank on a CNC horizontal lathe.

3. The method for preventing chip entanglement in high-strength structural steel rotating parts according to claim 2, characterized in that: The clamping size is not less than Φ12×10mm, and an A1.5 center hole is made at the tail of the part blank.

4. The method for preventing chip entanglement in high-strength structural steel rotating parts according to claim 1, characterized in that: In S2, a spiral groove with a depth of 0.1 mm is machined in a single operation, while a spiral groove with a cutting depth of 0.3 mm is machined in two operations, with the first operation having a cutting depth of 0.2 mm and the second operation having a cutting depth of 0.1 mm.

5. The method for preventing chip entanglement in high-strength structural steel rotating parts according to claim 1, characterized in that: In S3, the cutting parameters are: rotational speed S: 750 r / min, feed rate F: 0.27 mm / r, and the depth of cut is the same as the depth of the spiral groove. The cutting is completed in a single cut.

6. The method for preventing chip entanglement in high-strength structural steel rotating parts according to claim 1, characterized in that: The diameter of the blank rod of the part ranges from Φ6mm to Φ50mm, and the length-to-diameter ratio of the machined area is not greater than 10.

7. The method for preventing chip entanglement in high-strength structural steel rotating parts according to claim 1, characterized in that: The heat treatment strength range of the part blank is 980 MPa ≤ σ b ≤1960Mpa.

8. The method for preventing chip entanglement in high-strength structural steel rotating parts according to claim 1, characterized in that: The runout of the outer diameter of the blank rod should not exceed 0.03mm, and the straightness of the blank should not exceed 0.03mm, meaning the center of the spindle and the tailstock should be at the same height.