Machining track and machining method for single-point diamond ultra-precision lathe cutting

Abstract

The invention relates to the technical field of ultra-precision machining, and discloses a single-point diamond ultra-precision lathe cutting machining track and machining method.The single-point diamond ultra-precision lathe comprises a single-crystal diamond cutter, the single-crystal diamond cutter comprises a blade, and the operation path of a cutting edge, in contact with the surface of a workpiece, on the blade serves as the machining track. The machining track is used for cutting a sawtooth-shaped tip of the workpiece; the machining track comprises two extension lines on the two sides of the sawtooth-shaped tip end and an arc, and the two ends of the arc are tangent to the two extension lines respectively; the diameter of the arc is larger than the maximum width of cuttings generated by cutting the workpiece. A new machining track of the sawtooth-shaped tip is designed, the cutting edge extends out from the extension line of one side of the sawtooth-shaped tip and then is cut into the other side of the sawtooth-shaped tip through the arc, when the cutting edge is cut into the workpiece again, the track direction of the tool is not changed, the steering error is set on the track outside the surface of the workpiece, and the machining precision is improved. The integrity of the sawtooth-shaped tip is guaranteed, and shaking is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-precision machining, and in particular relates to a machining track and a machining method for single-point diamond ultra-precision turning. Background Art

[0002] Ultra-precision cutting is the process of fine machining of workpieces using high-precision lathes and designed tools. By precisely controlling the tool's motion trajectory and cutting parameters, extremely high machining accuracy and surface quality can be achieved. It can be used to manufacture high-precision parts in the fields of aerospace, electronics, and medical treatment, as well as for machining planes, spherical surfaces, aspherical surfaces, free-form surfaces, large-aperture aspherical surfaces, asymmetric free-form surfaces, optical elements and diffractive optical elements, Fresnel lenses and other microstructure elements.

[0003] The single-point diamond lathe is a type of ultra-precision cutting tool, suitable for processing non-ferrous metals such as copper and aluminum, as well as materials such as plastics. The surface finish of the processed parts needs to be very high to meet the high requirements of part surface quality in the fields of optics, biology, etc.

[0004] However, when cutting sawtooth-shaped workpieces, the chips generated during the processing of existing diamond tools are often unable to be discharged or dropped smoothly due to the existence of the lathe cooling air blind area and the continuous chip bands. For example, the strip-shaped chips entangle the tool, the space is narrow, the tool is blocked, other structures are blocked, etc., which make the cooling air unable to carry the chips away smoothly, thereby entangling the chips in the tool trajectory movement process, causing different degrees of scratches on the surface of the parts, affecting the surface quality and reducing the processing accuracy.

[0005] In addition, the machining trajectory often moves according to the shape of the workpiece during machining, and the sawtooth tip part often moves like Figure 1 The shape shown is an arc, and the arc trajectory oscillates and cannot meet the design requirements on the workpiece shape.

[0006] Therefore, it is urgent to design a machining trajectory and method for single-point diamond ultra-precision turning. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a single-point diamond ultra-precision turning processing trajectory and processing method, which reduces the process of chips entering the tool running trajectory to participate in processing, improves precision, avoids increasing the number of processing times, and saves time, manpower and cost.

[0008] In the first aspect, the first object of the present invention is to provide a processing trajectory for single-point diamond ultra-precision turning, wherein the single-point diamond ultra-precision lathe comprises a single-crystal diamond tool, the single-crystal diamond tool comprises a blade, and the running path of the blade at the contact point with the workpiece surface is used as the processing trajectory, and the processing trajectory is used to cut the serrated tip of the workpiece; the processing trajectory comprises two extension lines and an arc on both sides of the serrated tip, and the two ends of the arc are respectively tangent to the two extension lines; the diameter of the arc is greater than the maximum width of the chips generated by cutting the workpiece.

[0009] Furthermore, the maximum width of the chip is: the length of the trajectory from the blade cutting into the workpiece surface to the point where the blade reaches the workpiece surface again when the workpiece rotates one circle under a specific tool translation speed, workpiece rotation speed and cutting depth; wherein, The starting position of the blade cutting into the workpiece surface is: the intersection of the workpiece surface and the perpendicular midline of the tool translation line segment.

[0010] Furthermore, the translation distance of the tool when the workpiece rotates one circle is W, the starting point of the tool movement is set as the first position, and the end point of the tool movement is set as the second position; the trajectory length M is calculated by the following formula: , , , , in, , and To set the auxiliary angle, is the angle between the vertical line and the line connecting the point where the blade leaves the workpiece surface and the second position, is the angle between the vertical line and the line connecting the point where the blade cuts into the workpiece surface and the second position, It is the angle between the line connecting the point where the blade leaves the workpiece surface and the second position and the line connecting the point where the blade enters the workpiece surface and the second position. R is the radius corresponding to the blade arc of the tool, and H is the cutting depth.

[0011] Further, the distance W between the first position and the second position is calculated by the following formula: , Among them, v is the tool translation speed, and t is the time for the workpiece to rotate one circle.

[0012] Furthermore, the angle between the two sides of the sawtooth tip is 0°~180°.

[0013] Furthermore, the angle between the blade and any side of the serrated tip is greater than or equal to 5°.

[0014] In a second aspect, the present invention provides a single-point diamond ultra-precision turning processing method, which is a processing method for processing a sawtooth tip according to the processing trajectory of a single-point diamond ultra-precision lathe cutting described in the first aspect.

[0015] The embodiments of the present invention have the following technical effects: The present application designs a new machining trajectory of the sawtooth tip, so that the blade extends from the extension line of one side of the sawtooth tip, and then cuts into the other side of the sawtooth tip through an arc, so that when the tool cuts into the workpiece again, the trajectory direction of the tool does not change, and the steering error is set on the trajectory outside the workpiece surface, thereby ensuring the integrity of the sawtooth tip, avoiding the generation of jitter, and meeting the design requirements on the workpiece shape; The radius of the arc part is greater than the maximum width of the chip, so that the farthest distance between the arc and the serrated tip must be greater than the maximum width of the chip. When the tool is in the arc part, the chips can fall from the middle gap, reducing the process of chips entering the tool trajectory to participate in processing, thereby improving accuracy; avoiding increasing the number of processing times, saving time, manpower and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 is a structural schematic diagram of the current processing trajectory provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of a machining trajectory of a single-point diamond ultra-precision lathe cutting provided by an embodiment of the present invention; Figure 3 is a schematic diagram of a cutting process provided by an embodiment of the present invention; Figure 4 is a schematic diagram of a processing trajectory when the angle between the two sides of the sawtooth tip provided by an embodiment of the present invention is 20°; Figure 5 is a schematic diagram of a processing trajectory when the angle between the two sides of the sawtooth tip provided by an embodiment of the present invention is 90°; Figure 6 is a schematic diagram of a processing trajectory when the angle between the two sides of the sawtooth tip provided by an embodiment of the present invention is 135°; Figure 7 It is a schematic diagram of an actual machining trajectory of single-point diamond ultra-precision turning provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0019] Example 1 When the single-point diamond ultra-precision lathe is working, the workpiece must be installed on the spindle of the machine tool. The spindle rotates so that the workpiece rotates with the spindle. The rotation of the spindle provides the necessary cutting speed for the workpiece. The workpiece can be fed laterally through the guide rail so that the workpiece contacts the tool. The tool can also be fed laterally and cut along the surface of the workpiece to produce the required shape and size. The control system of the single-point diamond ultra-precision lathe is responsible for planning according to the given processing parameters and tool processing trajectory to generate accurate motion instructions, thereby realizing precise control of the relative displacement between the tool and the workpiece and completing ultra-precision cutting of the workpiece.

[0020] During the processing of single-point diamond ultra-precision lathes, a large amount of heat will be generated during cutting and grinding. If it is not discharged in time, the temperature of the cutting area will rise, which will affect the processing accuracy, equipment stability and service life. Therefore, cooling air is set to take away the heat to maintain the normal operating temperature of the lathe. However, cooling air will inevitably produce blind spots during the working process, making it impossible to discharge the chips normally, affecting subsequent processing.

[0021] Moreover, in the prior art, when cutting a serrated tip, the lathe tool has a certain inertia, and will produce a jittery trajectory due to sudden turning. The force of the servo motor cannot control the tool to reach the specified trajectory point, so that the actual trajectory and the theoretical trajectory produce an oscillating curve deviation. Therefore, it is necessary to improve the trajectory in order to achieve the purpose of processing into an optical-grade mirror in one go.

[0022] Figure 2 The double-dotted dashed line portion is a schematic diagram of a machining trajectory of a single-point diamond ultra-precision turning provided by an embodiment of the present invention. The single-point diamond ultra-precision lathe includes a single-crystal diamond tool, and the single-crystal diamond tool includes a blade. The running path of the blade at the contact point with the workpiece surface is used as the machining trajectory, and the machining trajectory is used to cut the sawtooth tip of the workpiece; the machining trajectory includes two extension lines and an arc on both sides of the sawtooth tip, and the two ends of the arc are tangent to the two extension lines respectively; the diameter of the arc is greater than the maximum width of the chips generated by cutting the workpiece.

[0023] It should be noted that this application uses the trajectory of the blade where the tool contacts the workpiece surface when cutting out as the processing trajectory; other points can also be used as processing trajectories, but the contact points between the tool and the workpiece surface when cutting in and out need to be kept consistent. Accordingly, the processing trajectory will also be converted to a corresponding scale according to the proportion to avoid errors.

[0024] Among them, the maximum width of the chip is: under specific tool translation speed, workpiece rotation speed and cutting depth, the trajectory length of the blade from cutting into the workpiece surface to reaching the workpiece surface again when the workpiece rotates one circle; wherein the starting position of the blade cutting into the workpiece surface is: the intersection of the workpiece surface and the perpendicular bisector of the tool translation line segment.

[0025] It should be noted that in the present application, the running track direction of the blade is defined as the width direction.

[0026] The trajectory length can be approximately calculated as follows: See also Figure 3 This is a schematic diagram of the cutting process when the workpiece rotates one circle. A circle is used to simply represent the tool's trajectory, and two circles are used to represent the change in the blade position. Assuming that the tool moves from right to left, the right part has been cut, and the workpiece rotates with the spindle. The tool cuts the workpiece to make it a plane. The shaded part in the figure is the cutting section.

[0027] In this process, the cutting depth is set to H. During one rotation of the workpiece, the tool moves horizontally from right to left, that is, the center of the circle on the right moves to the left by a distance W to obtain the circle on the left, realizing the translation of the tool from the first position to the second position. The distance between the first position and the second position is W.

[0028] If the radius of the blade arc is R, set the auxiliary angle , and , has no actual physical meaning. is the angle between the vertical line and the line connecting the point where the blade leaves the workpiece surface and the second position, is the angle between the vertical line and the line connecting the point where the blade cuts into the workpiece surface and the second position, It is the angle between the line connecting the point where the blade leaves the workpiece surface and the second position and the line connecting the point where the blade enters the workpiece surface and the second position. for and Half of the total angle, according to the geometric relationship, can be obtained as follows: , , , When cutting, start from point A where cutting begins. Point A is the intersection of the workpiece surface and the perpendicular midline of the tool translation line segment. The right side of point A is the cut plane, and the left side of point A is the part to be cut. The workpiece rotates with the spindle, and the tool translation distance W is calculated by the following formula: , v is the translation speed of the tool, and t is the time it takes for the workpiece to rotate one circle with the spindle. The workpiece and the tool cooperate with each other to perform relative displacement, so that the tool moves a distance W in the end.

[0029] The end point of the cutting is point B, which is the leftmost point where the tool and the workpiece are in contact and a point on the workpiece surface. The length of line segment AB is calculated to approximate the maximum width M of the chip: , Through the arc-shaped design, the tool will be lifted to remove chips when each tooth is processed to the tip. The tool and workpiece are separated by a certain distance, which must be greater than the maximum width of the chips, so that the lathe cooling air can blow the chips away from the workpiece surface and the tool tip; thereby ensuring that there is no chip interference when cutting a new tooth shape, which is beneficial to improving the accuracy of the workpiece surface and the surface quality of the workpiece after cutting.

[0030] In the present application, there is no limitation on the angle between the two sides of the sawtooth tip, which can be in the range of 0° to 180°. Figures 4 to 6 , provides schematic diagrams of various processing trajectories under different angle settings between the two sides of the sawtooth tip. Obviously, the distance Q between the farthest end of the processing trajectory and the sawtooth tip must be greater than the maximum width of the chip, which is conducive to the separation of the chip.

[0031] In this application, the machine tool uses an interpolation algorithm to accurately calculate and control the motion trajectory of the tool. The angle between the blade and any side of the serrated tip is greater than or equal to 5°. The blade includes a straight portion and an arc-shaped tip. For the straight portion, a certain angle needs to be formed between the straight portion and the workpiece surface to facilitate the cutting condition of the tool tip, reduce friction loss, and improve the rigidity and strength of the tool.

[0032] A moving object will keep moving in a straight line without the action of external force. If you want to change the direction of movement, you have to apply external force to the object. The greater the mass of the object, the greater the external force applied, and the greater the angle of change in direction, the greater the external force required. The direction of the tool's motion trajectory has changed, which means that the tool's motion state needs to be changed to do work. Since the motion mechanism that drives the tool on the machine tool is heavy, it is necessary to add sufficient external force to act on the tool, which will vibrate during movement, and jitter should be avoided. Compared with other shapes, the arc set in this application has a gradually changing vector force, which makes the cutting process smoother, thereby optimizing the cutting speed, feed rate, etc., and further improving the processing efficiency.

[0033] Therefore, the smaller the angle between the two sides of the sawtooth tip, the more likely it is to cause jitter if the required external force is insufficient, thus affecting the accuracy of the workpiece.

[0034] In the present application, the machining trajectory extends from one side of the serrated tip and then cuts in from the other side. The direction in which the tool cuts into the workpiece again is a straight line without changing the trajectory direction. Therefore, this direction is the direction in which the serrated tip can withstand the maximum stiffness. This can retain the integrity of the tip to the greatest extent, keep the tip sharp, and avoid the influence of tool mapping accuracy and trajectory jitter on the tip.

[0035] In addition, see Figure 7 In actual operation, the trajectory designed in this application will not move completely according to the theoretical trajectory, and will produce a certain degree of jitter, setting the steering error on the trajectory outside the tooling surface. The specific principle is: The equipment will produce a jittery trajectory line due to sudden turning, because the force of the servo motor cannot control the tool to reach the specified trajectory point. When the theoretical trajectory curvature is relatively straight, the actual trajectory line has a higher degree of overlap with the theoretical trajectory line. Therefore, this application puts the error caused by the turning on the trajectory outside the workpiece surface.

[0036] Based on the above technical solution, the present application sets the steering error on a trajectory outside the workpiece surface, ensuring the integrity of the serrated tip, avoiding the generation of jitter, and meeting the design requirements of the workpiece shape; reducing the process of chips entering the tool running trajectory to participate in processing, thereby improving accuracy; avoiding increasing the number of processing times, saving time, manpower and costs.

[0037] Example 2 Based on the content of Example 1, the present application provides a single-point diamond ultra-precision turning processing method, and the processing method of processing the sawtooth tip according to the processing trajectory in Example 1 is specifically as follows: The cutting edge of the single crystal diamond tool extends along the extension line of one side of the sawtooth tip, and then enters the extension line of the other side of the sawtooth tip along the arc to cut into the workpiece.

[0038] For other contents, please refer to Example 1, which will not be described in detail here.

[0039] It should be noted that the terms used in the present invention are only for describing specific embodiments, rather than limiting the scope of the present application. As shown in the present specification, unless the context clearly indicates an exception, the words "one", "a", "a kind of" and / or "the" do not specifically refer to the singular, but may also include the plural. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method or device. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the presence of other identical elements in the process, method or device including the elements.

[0040] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A machining trajectory for cutting by a single-point diamond ultra-precision lathe, the single-point diamond ultra-precision lathe comprising a single-crystal diamond tool, the single-crystal diamond tool comprising a blade, the running path of the blade edge at the contact point with the workpiece surface being used as the machining trajectory, the machining trajectory being used for cutting a sawtooth tip of a workpiece; characterized in that: The machining trajectory includes two extension lines and an arc on both sides of the sawtooth tip, and the two ends of the arc are tangent to the two extension lines respectively; the diameter of the arc is greater than the maximum width of the chips generated by cutting the workpiece; The maximum width of the chip is: the length of the trajectory from the time when the blade cuts into the workpiece surface to the time when it reaches the workpiece surface again when the workpiece rotates one circle under a specific tool translation speed, workpiece rotation speed and cutting depth; The starting position of the cutting edge cutting into the workpiece surface is the intersection of the workpiece surface and the perpendicular midline of the tool translation line segment.

2. The machining trajectory of a single-point diamond ultra-precision lathe cutting according to claim 1 is characterized in that: The translation distance of the tool when the workpiece rotates one circle is W, the starting point of the tool movement is set as the first position, and the end point of the tool movement is set as the second position; the trajectory length M is calculated by the following formula: ， ， ， ， in, , and To set the auxiliary angle, is the angle between the vertical line and the line connecting the point where the blade leaves the workpiece surface and the second position, is the angle between the vertical line and the line connecting the point where the blade cuts into the workpiece surface and the second position, It is the angle between the line connecting the point where the blade leaves the workpiece surface and the second position and the line connecting the point where the blade enters the workpiece surface and the second position. R is the radius corresponding to the blade arc of the tool, and H is the cutting depth.

3. The machining trajectory of a single-point diamond ultra-precision lathe cutting according to claim 2 is characterized in that: The distance W between the first position and the second position is calculated by the following formula: ， Among them, v is the tool translation speed, and t is the time for the workpiece to rotate one circle.

4. The machining trajectory of a single-point diamond ultra-precision lathe cutting according to claim 1 is characterized in that: The angle between the two sides of the sawtooth tip is 0°~180°.

5. The machining trajectory of single-point diamond ultra-precision lathe cutting according to claim 1 is characterized in that: The angle between the blade and any side of the sawtooth tip is greater than or equal to 5°.

6. A single-point diamond ultra-precision lathe cutting method, characterized in that: A method for machining a sawtooth tip according to a machining trajectory cut by a single-point diamond ultra-precision lathe as described in any one of claims 1-5.

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