A small-diameter, large-lead-angle internal spiral fluting turning tool and its design method

Abstract

This invention relates to the field of special-purpose cutting tools for machining, specifically to a small-diameter, large-lead-angle internal spiral groove turning tool and its design method, comprising: S1, calculating the spiral groove pitch diameter, lead angle, and helix angle based on the lead of the internal spiral groove, the internal diameter, and the diameter of the spiral groove cross-section; S2, simulating the tangent plane at the starting position of the turning tool when machining the product based on the obtained lead angle and helix angle, and determining the angles of the rake face and flank face of the turning tool; S3, designing the profile dimensions of the cutting part of the turning tool to match the profile dimensions of the spiral groove cross-section; S4, determining the diameter of the turning tool shank and the center height of the turning tool based on the internal diameter and the lathe machining method.

Description

Technical Field

[0001] This invention relates to the field of special cutting tools for machining, specifically to a small-diameter, large-lead-angle internal helical groove turning tool and its design method, which can provide technical support for the design of different internal helical groove turning tools and the machining and manufacturing of helical grooves. Background Technology

[0002] Oil-filled bushings are sliding bearing bushings with lubrication channels or oil inlets. The inner surface of the oil-filled bushing is designed with spiral oil grooves, which can continuously and stably distribute lubricating oil evenly to the friction surface, reducing friction and wear of parts. In addition, oil-filled bushings have a strong environmental adaptability and are now widely used in various mechanical equipment, especially in occasions where frequent maintenance is required or lubricant is difficult to change regularly, such as aircraft engine bearings, landing gear systems and hydraulic systems.

[0003] The spiral groove of the oil-filled bushing is an internal spiral groove with a certain lead angle. Currently, the main method for machining internal spiral grooves is milling and turning using high-end CNC equipment, relying entirely on the intelligence of the equipment to ensure product machining quality, which is costly. For ordinary lathes, there is little record of how to machine small-diameter, large-lead-angle internal spiral grooves through tool design improvements. This invention will introduce a small-diameter, large-lead-angle internal spiral groove machining tool for use on ordinary lathes and its design method. Summary of the Invention

[0004] The purpose of this invention is:

[0005] The purpose of this invention is to provide an innovative turning tool design method. Taking a conventional lathe as an example, starting from the design principle of the turning tool and the machining method of the lathe, a new type of turning tool is designed to achieve efficient and precise machining of small-diameter, large-lead-angle internal spiral grooves, solving the challenges faced by existing machining technologies and breaking through the limitations of traditional machining methods.

[0006] The technical solution of this invention is as follows:

[0007] This invention provides a design method for a small-diameter, large-lead-angle internal helical groove turning tool. The turning tool consists of a tool holder, a tool shank, and a cutting part. The tool design method includes the following steps: S1. Calculate the helical groove pitch diameter, lead angle, and helix angle based on the lead, internal diameter, and helical groove diameter; S2. Based on the obtained lead angle and helix angle, simulate the tangent plane at the starting position of the turning tool when machining the product, and determine the angles of the rake face and flank face of the turning tool; S3. Design the profile dimensions of the cutting part of the turning tool to match the profile dimensions of the helical groove cross-section; S4. Determine the tool shank diameter and the tool center height based on the product's internal diameter and the lathe machining method.

[0008] Specifically, in step S1, the mean diameter d1 of the spiral groove is calculated based on the inner diameter D, the diameter d of the spiral groove cross section, and the groove depth h, where d1 = D + 2h - 2*(d / 2); the lead angle r and the spiral angle a are calculated based on the lead P, where r = arctan(P / (π*d1)) and a = 90° - r.

[0009] Specifically, in step S2, by analyzing the machining state of the cutting tool when machining the inner annular groove without lead angle, it can be seen that the angle between the inner annular groove without lead angle and the horizontal line after it is unfolded is 0°. At this time, the tangent plane is the vertical plane P1. Only when the cutting tool rake face is perpendicular to this vertical plane can the complete annular groove R-shaped surface be machined. Therefore, when machining a spiral groove with a lead angle, the spiral groove must first be unfolded in the same plane. The angle between the unfolded spiral groove line and the horizontal line is the spiral angle α. Then, the tangent plane P2 is simulated through the starting machining position of the spiral groove. The rake face of the cutting tool is designed to be perpendicular to P2. At this time, the angle between the rake face of the cutting tool and the horizontal line is α. Assuming the cutting edge inclination angle of the cutting tool is α1, we know that α1 = -α based on the position of the cutting tool tip relative to the base plane. The design of the flank face angle must consider both the strength of the cutting tool and that it should not interfere with the spiral groove being machined. Taking both factors into account, the flank face is made parallel to the simulated tangent plane P2. In this way, the flank face of the cutting tool does not interfere with the spiral groove and can maximize the strength of the cutting tool. At this time, the angle between the flank face and the rake face is 90°.

[0010] Specifically, in step S3, the dimensions of the cutting part of the lathe tool are determined based on the diameter d of the spiral groove cross-section and the groove depth h. It is required that the arc diameter d2 of the cutting part of the lathe tool is equal to the diameter d of the groove cross-section, so as to ensure that the arc diameter machined by the cutting part of the lathe tool is the required diameter d of the spiral groove cross-section. The arc height h1 of the arc of the cutting part of the lathe tool is greater than the groove depth h, so as to ensure that the groove depth of the spiral groove machined by the cutting part of the lathe tool meets the product requirements.

[0011] Specifically, in step S4, the machining method for the internal spiral groove is a conventional lathe with a straight-line cutting method. In order to ensure that the cutting tool can rotate flexibly in the internal hole without interfering with the internal hole wall when machining the spiral groove, the cutting tool shank diameter d3 + cutting tool arc sagitta height h1 is required to be less than the internal hole diameter D. At the same time, d3 needs to take into account the strength of the cutting tool shank, and the strength of the cutting tool shank should be increased as much as possible when space allows. According to the machining characteristics of the lathe, the height H1 from the center of the cutting part of the cutting tool to the bottom of the cutting tool shank should be equal to the center height required for machining on the lathe, to ensure that the height of the cutting part of the cutting tool matches the height of the workpiece.

[0012] The beneficial effects of this invention are as follows:

[0013] The beneficial effect of this invention is that it systematically proposes a set of solutions based on the design principles and simulation of turning tools, starting from the key parameters of the internal helical groove (internal diameter, lead and helical groove size). This enables the calculation and optimization of each key parameter of the turning tool, ensuring that the designed turning tool can also machine the internal helical groove that meets the requirements on a conventional lathe. This provides a theoretical basis and practical guidance for the research and development of turning tools with internal helical grooves of different specifications. Attached Figure Description

[0014] Figure 1 3D schematic diagram of a spiral grooving tool;

[0015] Figure 2 Drawing of the part with the helical groove in the inner hole to be machined;

[0016] Figure 3 Schematic diagram of thread lead angle;

[0017] Figure 4 Schematic diagram simulating the starting machining position of the lathe tool;

[0018] Figure 5 Schematic diagram of the cutting section of the lathe tool;

[0019] Figure 6 Two-dimensional design drawing of spiral groove turning tool;

[0020] Explanation of the numbering in the diagram:

[0021] D - Inner diameter of part, d - Diameter of spiral groove section, h - Spiral groove depth, d1 - Mean diameter of spiral groove, a - Spiral groove helix angle, D_middle - Mean diameter of thread, r - Lead angle of spiral groove, P - Lead of spiral groove, P1 - Tangent plane at the starting machining position of inner annular groove without lead angle, P2 - Tangent plane at the starting machining position of inner annular groove with lead angle, a1 - Cutting tool inclination angle, d3 - Diameter of tool holder, h1 - Sagitta height of cutting part of cutting tool, d2 - Diameter of arc of cutting part of cutting tool, H1 - Height from the center of cutting part of cutting tool to the bottom of tool holder, abbreviated as center height. Detailed Implementation

[0022] The embodiments described below are examples used to illustrate the implementation of the present invention. They are merely examples and are not intended to limit the scope of the invention.

[0023] like Figure 1A design method for a small-diameter, large-lead-angle internal helical groove turning tool is disclosed, characterized in that the turning tool consists of a tool holder, a tool shank, and a cutting part. The tool design method includes the following steps: S1, calculating the helical groove pitch diameter, lead angle, and helix angle based on the lead, internal diameter, and helical groove diameter; S2, simulating the tangent plane at the starting position of the turning tool when machining the product based on the obtained lead angle and helix angle, and determining the angles of the rake face and flank face of the turning tool; S3, designing the profile dimensions of the cutting part of the turning tool to match the profile dimensions of the helical groove cross-section; S4, determining the tool shank diameter and tool center height based on the internal diameter of the product and the lathe machining method.

[0024] like Figure 2-3 Based on the inner diameter D, the diameter d of the spiral groove section and the groove depth h, the mean diameter d1 of the spiral groove is calculated, d1=D+2h-2*(d / 2); based on the lead P, the lead angle r and the spiral angle a of the spiral groove are calculated, r=arctan(P / (π*d1)), a=90°-r.

[0025] like Figure 4 By analyzing the machining state of the inner annular groove without lead angle when the cutting tool is used, it can be seen that the angle between the inner annular groove without lead angle and the horizontal line after it is unfolded is 0°. At this time, the tangent plane is the vertical plane P1. Only when the cutting tool rake face is perpendicular to this vertical plane can the complete annular groove R-shaped surface be machined. Therefore, when machining a spiral groove with a lead angle, the spiral groove must first be unfolded in the same plane. The angle between the unfolded spiral groove line and the horizontal line is the spiral angle α. Then, the tangent plane P2 is simulated through the starting machining position of the spiral groove. The rake face of the cutting tool is designed to be perpendicular to P2. At this time, the angle between the rake face of the cutting tool and the horizontal line is α. Assuming the cutting edge inclination angle of the cutting tool is α1, we know that α1 = -α based on the position of the cutting tool tip relative to the base plane. The design of the flank face angle must consider both the strength of the cutting tool and that it should not interfere with the spiral groove being machined. Taking both factors into account, the flank face is made parallel to the simulated tangent plane P2. In this way, the flank face of the cutting tool does not interfere with the spiral groove and can maximize the strength of the cutting tool. At this time, the angle between the flank face and the rake face is 90°.

[0026] like Figure 5 Based on the diameter d and depth h of the spiral groove cross-section, the dimensions of the cutting part of the lathe tool are determined. It is required that the arc diameter d2 of the cutting part of the lathe tool is equal to the diameter d of the groove cross-section. This ensures that the arc diameter machined by the cutting part of the lathe tool is the required diameter d of the spiral groove cross-section. The arc height h1 of the arc of the cutting part of the lathe tool is greater than the groove depth h. This ensures that the groove depth of the spiral groove machined by the cutting part of the lathe tool meets the product requirements.

[0027] like Figure 5The machining method for the internal spiral groove is a conventional lathe with a straight-line cutting method. In order to ensure that the cutting tool can rotate flexibly in the internal hole without interfering with the internal hole wall when machining the spiral groove, the cutting tool shank diameter d3 + cutting tool arc sagitta height h1 must be less than the internal hole diameter D. At the same time, d3 needs to take into account the strength of the cutting tool shank, and the strength of the cutting tool shank should be increased as much as possible within the space. According to the machining characteristics of the lathe, the height H1 from the center of the cutting part of the cutting tool to the bottom of the cutting tool shank must be equal to the center height required for machining on the lathe, to ensure that the height of the cutting part of the cutting tool matches the height of the workpiece.

[0028] At this point, the key parameters of the cutting tool, such as the rake face, flank face, profile dimensions, and tool holder diameter, have all been designed.

[0029] In this embodiment:

[0030] like Figure 2 As shown, when the inner diameter D = φ12, the lead P = 80, the spiral groove diameter d = φ2, and the groove depth h = 0.4, the cutting tool design is as follows:

[0031] 1. Based on the inner diameter D=φ12, the diameter of the spiral groove section d=φ2, and the groove depth h=0.4, the mean diameter of the spiral groove d1=12+0.4*2-1*2=φ10.8. Then, based on the lead P=80, the lead angle r=arctan(P / (π*d1))=arctan(80 / (10.8*3.14))=67° and the helix angle a=90°-r=90°-67°=23°.

[0032] 2. By analyzing the machining state when the cutting tool is machining without a lead angle, it can be seen that a complete R-shaped surface of the annular groove can only be machined when the rake face of the cutting tool is perpendicular to the tangent plane at the starting machining position. In this example, the helix angle of the spiral groove is 23°. The angle between the tangent plane at the starting machining position and the horizontal plane is 90°-23°=67°. The rake face of the cutting tool must be perpendicular to the tangent plane. At this time, the angle between the rake face of the cutting tool and the horizontal plane is a=23°. According to the position of the cutting tool tip relative to the base plane, the cutting edge inclination angle a1=-a=-23°. The design of the flank face angle must consider both the strength of the cutting tool and that it should not interfere with the spiral groove being machined. The flank face is taken to be parallel to the tangent plane. At this time, the angle between the flank face and the rake face is 90°.

[0033] 3. Based on the diameter of the spiral groove section d=φ2 and the groove depth h=0.4, determine the profile dimensions of the cutting part of the lathe tool. It is required that the arc diameter of the cutting part of the lathe tool d2=the diameter of the groove section d=φ2, the arc height h1 of the arc of the cutting part of the lathe tool>the groove depth h=0.4, and h1 is taken as 1.5.

[0034] 4. The machining method for the internal helical groove is a conventional lathe with a straight-line cutting method. To ensure the cutting tool can rotate freely within the internal hole without interfering with the hole wall during machining, the cutting tool shank diameter d3 + cutting tool arc sagitta height h1 = 1.5 < internal hole diameter D = φ12, d3 < 12 - 1.5 = 10.5. To ensure the strength of the cutting tool and provide adequate machining space within the internal hole, d3 = 9.5 is chosen. The required center height of the lathe used for machining is 25, and the center height of the cutting part of the cutting tool is designed to be 25.

[0035] 5. At this point, all key parameters of the cutting tool have been designed, such as... Figure 6 As shown.

[0036] The above description is merely a preferred embodiment of this application and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of this application.

Claims

1. A design method for a small-diameter, large-lead-angle internal spiral flute turning tool, characterized in that, The lathe tool comprises a tool holder, a tool shank, and a cutting part; the method includes: S1. Calculate the mean diameter of the spiral groove, the lead angle, and the helix angle based on the lead of the inner hole spiral groove, the inner hole diameter, and the diameter of the spiral groove cross section. S2. Based on the obtained lead angle and helix angle, simulate the tangent plane at the starting position of the lathe tool when machining the product, and determine the angle between the rake face and the flank face of the lathe tool; S3. Based on the profile dimensions of the spiral groove cross-section, design the profile dimensions of the cutting part of the lathe tool to match it; S4. Determine the tool holder diameter and tool center height based on the inner hole diameter and lathe machining method; By analyzing the machining state of the inner annular groove without lead angle, it can be seen that the angle between the inner annular groove without lead angle and the horizontal line after it is unfolded is 0°. At this time, the tangent plane is the vertical plane P1. Only when the rake face of the cutting tool is perpendicular to this vertical plane can the complete R-shaped surface of the annular groove be machined. In step S2, when machining the spiral groove with a lead angle, the spiral groove is first unfolded in the same plane. The angle between the unfolded spiral groove line and the horizontal line is the spiral angle α. The tangent plane P2 is simulated through the starting machining position of the spiral groove. The rake face of the cutting tool is designed to be perpendicular to P2. At this time, the angle between the rake face of the cutting tool and the horizontal line is α. The cutting edge inclination angle of the cutting tool is obtained as a1 = -α based on the position of the cutting tool tip relative to the base surface. In step S2, the design of the flank face angle is as follows: the flank face is parallel to the simulated tangent plane P2, and the angle between the flank face and the front face is 90°. In step S3, based on the diameter d of the spiral groove cross-section and the groove depth h, the diameter d2 of the arc of the cutting part of the cutting tool is determined to be equal to the diameter d of the groove cross-section; the arc height h1 of the arc of the cutting part of the cutting tool is greater than the groove depth h. In step S4, the diameter of the cutting tool shank d3 + the arc height of the cutting tool h1 is less than the inner diameter D. The strength of the tool shank is increased if space permits. The height H1 from the center of the cutting part of the cutting tool to the bottom of the tool shank is equal to the center height required for lathe machining. The machining method for the inner spiral groove is ordinary lathe + straight-line cutting.

2. The design method of a small-diameter, large-lead-angle internal spiral fluting turning tool according to claim 1, characterized in that, In step S1, the mean diameter of the spiral groove d1 is calculated based on the inner diameter D, the diameter of the spiral groove cross section d, and the groove depth h, where d1 = D + 2h - 2*(d / 2); the lead angle r and the spiral angle a are calculated based on the lead P, where r = arctan(P / (π*d1)) and a = 90° - r.

3. A small-diameter, large-lead-angle internal spiral fluting turning tool, characterized in that, The design is performed using the method described in any one of claims 1-2.

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