Structural improvement and innovative design method and system for grinding trajectory of ultrasonic straight-edge cutter

Abstract

The present invention discloses a structural improvement and innovative design method and system for the grinding trajectory of an ultrasonic straight-edge knife. The method includes: Step 1, based on the analysis of the structure of the ultrasonic straight-edge knife body, a model with a smooth transition of the cutting edge is proposed and the design is improved; Step 2, a workpiece coordinate system XYZ is established at the center of the root of the straight-edge knife tool. Under this coordinate system, a model with a smooth transition of the cutting edge is established, including the mathematical models of the parallel cutting edge curve, the arc cutting edge curve, and the end straight-edge curve; Step 3, verify whether the cutting edge curve has a smooth transition and check the correctness of the cutting edge curve model; Step 4, establish a local coordinate system X L Y L Z L ; Step 5, calculate the position of the grinding wheel center in the local coordinate system according to the grinding posture of the grinding wheel, including the grinding wheel center position and the grinding wheel axis vector; Step 6, obtain the expression of the grinding wheel center in the workpiece coordinate system through coordinate transformation, and obtain the grinding trajectory of the grinding wheel for the smooth transition of the ultrasonic knife cutting edge.

Description

Technical Field

[0001] The invention belongs to the technical field of tool processing, and relates to a structural improvement and precision grinding processing technology of an ultrasonic tool, and in particular to a structural improvement and a grinding track innovative design method of an ultrasonic straight-edge knife. Background Art

[0002] This type of ultrasonic tool is a non-standard tool with a special purpose. It is mainly used for processing and cutting composite materials in the aerospace field such as aramid honeycombs. Therefore, it has extremely high requirements for the symmetry and surface accuracy of the tool. Since the cutting process is performed under the assistance of ultrasound, the wear of the tool by ultrasonic vibration will also increase, which also requires that such tools must have higher surface quality. This type of tool is a multi-linear combination plane tool, consisting of four blade lines, which are symmetrically distributed on both sides of the tool center line. The angle between the two blade lines on a single side is 170°, and there is no smooth transition between the connected blade surfaces. The existing processing method is to grind a single blade surface at a fixed angle, and finally process 8 blade surfaces that are symmetrically distributed up and down, left and right.

[0003] The working part of the improved arc ultrasonic knife mainly includes a straight blade and an arc blade. Starting from the establishment of a mathematical model of the blade curve, the grinding process is set for the blade surface. At present, there are many studies on the grinding technology of vertical milling cutters, but there are few studies on the grinding transition of the blade surface. Based on this, the present invention mainly studies the mathematical modeling of the arc transition of the ultrasonic straight blade knife, and the tool position trajectory algorithm when the grinding wheel grinds each blade surface. Summary of the invention

[0004] In view of the problems existing in the arc transition of the blade and the grinding trajectory of the blade surface of the ultrasonic straight-edge knife in the prior art, the present invention proposes a method and system for improving the structure and innovatively designing the grinding trajectory of the ultrasonic straight-edge knife.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for improving the structure of an ultrasonic straight-edge knife and innovating the design of a grinding track comprises the following steps:

[0007] Step 1: Based on the analysis of the structure of the ultrasonic straight blade, a model of blade smooth transition is proposed;

[0008] Step 2, establishing a workpiece coordinate system XYZ at the root center of the straight-edge knife, and establishing a model of smooth transition of the blade in this coordinate system, including mathematical models of parallel blade curve, arc blade curve and end straight blade curve;

[0009] Step 3: Verify whether the blade curve has a smooth transition and check the correctness of the blade curve model;

[0010] Step 4: Establish a local coordinate system X based on the grinding moving point P according to the processing technology of the ultrasonic straight blade knife L Y L Z L ;

[0011] Step 5, according to the grinding posture of the grinding wheel, calculate the position of the grinding wheel center in the local coordinate system, including the grinding wheel center position and the grinding wheel axis vector;

[0012] Step six, through coordinate transformation, the expression of the grinding wheel center in the workpiece coordinate system can be obtained, and the grinding trajectory of the grinding wheel with smooth transition of the ultrasonic knife blade can be obtained.

[0013] Preferably, in step one, the structure shape of the ultrasonic straight-edge knife body is symmetrical up and down and left and right, the angle between the two blade lines on one side is 170°, and there is no smooth transition between the corresponding blade surfaces.

[0014] Preferably, step one is improved in design, and after the improved design, the blade can have a smooth transition.

[0015] This ultrasonic tool is a non-standard tool for processing special materials. First, the structural parameters of the tool need to be defined. The total length of the tool is L = 55.7mm; the width of the tool tail is b = 13mm; the length of the tail straight edge when the blade is not arc-transitioned is H1 = 23.09mm; the angle between the two straight edges at the end is 20°; the angle between the upper and lower blade surfaces is β = 26°; the thickness of the tool is d = 1.6mm. Considering that there are edges and corners between the adjacent edge lines on both sides of this type of ultrasonic tool, the blade does not form a smooth transition, which affects the durability and finish of the tool, and causes the phenomenon that the cutting is not easy to flow out during processing. Therefore, the two adjacent straight edges are designed as parallel blades, arc blades, and end straight blades with three arc transitions, among which the arc blade forms an arc transition connection with the other two blades. This design will correspondingly improve the surface quality of the ultrasonic tool during processing and reduce the wear of the tool on the ultrasonic vibration.

[0016] Preferably, in step 2, a workpiece coordinate system XYZ is established and fixed on the workpiece, the coordinate origin is located at the starting center point of the tool tail, the coordinate axis X coincides with the axis of the workpiece, and the directions of the coordinate axes Y and Z are determined by the right-hand rule. The coordinate system is used to describe the geometric parameters and geometric shape of the tool. The smooth transition blade curve established based on the workpiece coordinate system is as follows:

[0017] (1) Parallel blade curve:

[0018] (2) Arc blade curve:

[0019] (3) End straight edge curve: Define the tool geometry parameters after arc transition: L1 is the parallel blade length, L1 =H 1 -c;R t is the custom radius of the arc blade; c is R t The sine value of c = R t tan(α / 2); θ is the center angle of the arc segment of the tool, that is, the angle between the tangent of the arc blade and the X-axis direction, 0≤θ≤10°; L2 is the straight-line distance from the origin of the workpiece coordinate system to the end point of the arc blade, L 2 =H 1 +c·cos(α); α is the angle between the end straight blade curve and the X axis, that is, half of the angle between the two straight blades at the end, α = 10°; a is half of the blade tip width, a = b / 2-(LH 1 )·tan(α).

[0020] Preferably, in step three, in order to verify the correctness of the established blade curve model, the blade curve model of arc transition is three-dimensionally simulated in Matlab, and the simulation results show that the blade curve model of arc transition is correct.

[0021] Preferably, in step 4, the grinding moving point P is defined as a point on the edge of the grinding surface of the grinding wheel, and a local coordinate system X is established based on the grinding moving point P. L Y L Z L The local coordinate system is obtained by rotation and translation transformation of the workpiece coordinate system; the origin O of the local coordinate system is located on the blade line, and the cutting plane of the blade is made through this point. The plane must pass through the center of the grinding wheel, and the radius of the grinding wheel diameter on the cutting plane is the real radius R of the tool. g ; Define the tangent direction of the blade curve as coordinate system X L , coordinate axis Y L It is in the normal direction of the blade curve, and the coordinate axis Z L It is on the blade surface; the local coordinate system is used to determine the relative positions of different parts of the grinding wheel machining tool, and to solve the grinding trajectory of the grinding wheel when grinding the blade surface. The coordinate system moves with the grinding point on the blade curve.

[0022] Preferably, in step 4, the grinding moving point P is defined as a point on the edge of the grinding surface of the grinding wheel, and a local coordinate system X based on the grinding moving point P is established according to the processing technology of the ultrasonic straight blade knife. L Y L Z L The local coordinate system is obtained by rotating and translating the workpiece coordinate system. First, translate the workpiece coordinate system XYZ to the blade curve, (x, y, z) is any point on the blade. The translated coordinate system is XYZ 1m , whose translation matrix T 1 :

[0023]

[0024] Preferably, in step five, the grinding wheel used for grinding the ultrasonic tool is a CBN bowl-type grinding wheel, and the grinding method is to grind the blade surface with the large end face of the bowl-type grinding wheel, and the upper and lower blade surfaces naturally form a blade; the grinding wheel center is defined as the geometric center of the grinding wheel grinding surface, and the posture of the grinding wheel grinding blade surface is defined through a specific grinding process method, and the position of the grinding wheel center in the normal section coordinate system is solved based on this grinding posture.

[0025] Preferably, in step 5, the position of the grinding wheel center in the local coordinate system is calculated based on the grinding wheel grinding posture, including the grinding wheel center position and the grinding wheel axis vector. In the actual grinding process, the fixture clamps the tail side of the tool, and the first thing to be ground is the end edge of the tool, so the calculation starts from the grinding trajectory of the end edge of the tool. After obtaining the translation matrix in step 4, the coordinate system XYZ is converted to 1m Around Z 1m The axis rotates counterclockwise by an angle α to obtain the coordinate system XYZ 2m , whose rotation matrix is ​​T 2 , and then the coordinate system XYZ 2m Around X 2m Axis rotation clockwise Get the local coordinate system X L Y L Z L , whose rotation matrix is ​​T 3 .

[0026]

[0027] The position of the grinding point P in the local coordinate system:

[0028]

[0029] The position of the grinding wheel center in the local coordinate system:

[0030] The expression of the grinding wheel axis vector in the local coordinate system is:

[0031] (1) Through coordinate transformation, the expression of the grinding wheel center in the workpiece coordinate system when grinding the cutting edge of the tool end is:

[0032]

[0033] Similarly, the expression of the grinding wheel axis vector in the workpiece coordinate system when grinding the cutting edge of the tool end is:

[0034]

[0035] (2) The grinding trajectory of the arc part of the tool blade is expressed as follows:

[0036] After obtaining the translation matrix in step 4, the coordinate system XYZ 1m Around Z 1m The axis rotates counterclockwise by angle θ to obtain the coordinate system XYZ 2m , whose rotation matrix is ​​T 2 ', then the coordinate system XYZ 2m Around X 2m Axis rotation clockwise Get the coordinate system X L Y L Z L , whose rotation matrix is ​​T 3 , same as above.

[0037]

[0038] Through coordinate transformation, the expression of the grinding wheel center in the workpiece coordinate system when grinding the arc part of the cutting edge of the tool is:

[0039]

[0040] Similarly, when grinding the arc part of the cutting edge of the tool, the expression of the grinding wheel axis vector in the workpiece coordinate system is:

[0041]

[0042] (3) The grinding trajectory of the parallel blade surface at the tail of the tool is expressed as follows:

[0043] After obtaining the translation matrix in step 4, the coordinate system XYZ 1m Around X 1m Axis rotation clockwise Get the coordinate system X L Y L Z L , whose rotation matrix is ​​T 3 .

[0044] Through coordinate transformation, the expression of the grinding wheel center in the workpiece coordinate system when grinding the tail of the tool parallel to the blade surface is:

[0045]

[0046] Similarly, when the tail of the grinding tool is parallel to the cutting edge, the expression of the grinding wheel axis vector in the workpiece coordinate system is:

[0047]

[0048] Preferably, in step six, the expression of the grinding wheel center in the workpiece coordinate system is obtained by coordinate conversion between the local coordinate system and the workpiece coordinate system, and the grinding trajectory of the grinding wheel with respect to the smooth transition of the ultrasonic knife blade is expressed as follows:

[0049] (1) Parallel blade grinding track:

[0050]

[0051] Where T 1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system;

[0052] When parallel blade surface grinding is performed, the expression of the grinding wheel axis vector in the workpiece coordinate system is:

[0053]

[0054] Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system;

[0055] (2) Grinding trajectory of circular blade edge:

[0056]

[0057] Where T 1 is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; T' 2 , T 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system;

[0058] The expression of the grinding wheel axis vector in the workpiece coordinate system during arc blade grinding is:

[0059]

[0060] Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system;

[0061] (3) Grinding track of the end blade surface:

[0062]

[0063] Where T1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 2 , T 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system;

[0064] When grinding the end blade surface, the expression of the grinding wheel axis vector in the workpiece coordinate system is:

[0065]

[0066] Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system.

[0067] The present invention also discloses a structural improvement and grinding track innovation design system for an ultrasonic straight-edge knife, comprising the following modules:

[0068] A module for proposing a blade smooth transition model is proposed. Based on the analysis of the structure of the ultrasonic straight-edge knife body, a blade smooth transition model is proposed.

[0069] The module for establishing the smooth transition model of the blade is to establish the workpiece coordinate system XYZ at the root center of the straight blade tool, and to establish the model of the smooth transition of the blade in this coordinate system, including the mathematical models of the parallel blade curve, the arc blade curve and the end straight blade curve;

[0070] Verification module, verifying whether the blade curve has a smooth transition and checking the correctness of the blade curve model;

[0071] The coordinate system establishment module establishes the local coordinate system X based on the grinding moving point P according to the processing technology of the ultrasonic straight blade knife. L Y L Z L ;

[0072] The position calculation module calculates the position of the grinding wheel center in the local coordinate system according to the grinding wheel grinding posture, including the grinding wheel center position and the grinding wheel axis vector;

[0073] The module outputs the grinding trajectory of the smooth transition of the ultrasonic knife blade, obtains the expression of the grinding wheel center in the workpiece coordinate system through coordinate transformation, and obtains the grinding trajectory of the grinding wheel about the smooth transition of the ultrasonic knife blade.

[0074] The beneficial effects of the present invention are:

[0075] Based on the geometric structure characteristics of the multilinear combination plane of the ultrasonic tool, the present invention designs a mathematical model for the arc transition of the tool edge line, constructs a local coordinate system with the grinding moving point P as the coordinate origin, and on this basis, establishes a new grinding model for the ultrasonic tool blade surface through the principle of coordinate transformation, calculates the motion trajectory of the grinding wheel during the grinding of the blade surface, and realizes a smooth transition between the blade and its blade surface. This makes up for the theoretical deficiency that such tools can only be ground at a fixed angle in the grinding process, and provides a reference for such tools in the process of solving the grinding trajectory algorithm. The present invention improves the surface quality of ultrasonic tools during grinding, reduces the wear of ultrasonic vibration on the tool, and increases the service life of such ultrasonic tools. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 It is a flow chart of the structural improvement of ultrasonic tools and the innovative design method of grinding trajectory.

[0077] Figure 2 It is a schematic diagram of the structure of the ultrasonic straight-edge knife body, including the structural parameters of the tool.

[0078] Figure 3 It is a schematic diagram of the ultrasonic tool structure after structural improvement, including specific structural parameters.

[0079] Figure 4a-4c This is a schematic diagram of the grinding posture of the grinding wheel when grinding the end edge of the tool, the arc edge, and the parallel edge. For coordination, the grinding wheel is reduced by 0.5 times. Specifically, it includes the positions of the workpiece coordinate system and the local coordinate system.

[0080] Figure 5 This is a simulation diagram of the tool edge line after the arc transition.

[0081] Figure 6 It is a schematic diagram of the CBN grinding wheel profile and the position of the grinding moving point P.

[0082] Figure 7 It is a system block diagram of the structural improvement and grinding trajectory innovation design of the ultrasonic straight-edge knife. DETAILED DESCRIPTION

[0083] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0084] like Figure 1-6 As shown, the present embodiment provides a method for improving the structure of an ultrasonic straight-blade knife and innovating the design of a grinding track, including the following steps:

[0085] Step 1: Based on the analysis of the structure of the ultrasonic straight blade, a model for the smooth transition of the blade is proposed and the design is improved;

[0086] Step 2: Establish a workpiece coordinate system XYZ at the root center of the straight blade tool, and establish a model of blade smooth transition in this coordinate system, including mathematical models of parallel blade curve, arc blade curve and end straight blade curve;

[0087] Step 3: Verify whether the blade curve has a smooth transition in Matlab and check the correctness of the blade curve model;

[0088] Step 4: Establish the local coordinate system X based on the grinding moving point P according to the processing technology of the ultrasonic straight blade L Y L Z L ;

[0089] Step 5: Calculate the position of the grinding wheel center in the local coordinate system based on the grinding wheel grinding posture, including the grinding wheel center position and the grinding wheel axis vector;

[0090] Step 6: The expression of the grinding wheel center in the workpiece coordinate system can be obtained through coordinate transformation, and the grinding trajectory of the grinding wheel with smooth transition of the ultrasonic knife blade can be obtained.

[0091] In step 1, there are edges and corners between the adjacent blade lines on both sides of this type of ultrasonic tool, and the blade does not form a smooth transition. The two adjacent straight blades are designed as three arc transition blades: a parallel blade, an arc blade, and an end straight blade. The arc blade forms an arc transition connection with the other two blades. After the improved design of step 1, the blade can have a smooth transition.

[0092] Specifically, the angle between two adjacent straight edges is made into an angle bisector, and a point A is selected on the angle bisector, so that the distance from point A to the two straight edges is R. t , with point A as the center of the circle R t Draw an arc with the radius, which intersects the two straight blades at points B and C. The arc BC is the arc blade curve. The straight line from the end of the blade to point B is the end straight blade, and the straight line from the end of the blade to point C is the parallel blade. Figure 3 .

[0093] In step 2, a workpiece coordinate system is established and fixed on the workpiece. The coordinate axis X coincides with the axis of the workpiece, and the directions of the coordinate axes Y and Z are determined by the right-hand rule. This coordinate system is used to describe the geometric parameters and geometric shape of the tool. The smooth transition blade curve established based on the workpiece coordinate system is as follows:

[0094] (1) Parallel blade curve:

[0095] (2) Arc blade curve:

[0096] (3) End straight edge curve: Define the tool geometry parameters after arc transition: L1 is the parallel blade length, L 1 =H 1 -c;R t is the custom radius of the arc blade; c is R t The sine value of, c = R t tan(α / 2); θ is the center angle of the arc segment of the tool, that is, the angle between the tangent of the arc blade and the X-axis direction, 0≤θ≤10°; L2 is the straight-line distance from the origin of the workpiece coordinate system to the end point of the arc blade, L 2 =H 1 +c·cos(α); α is the angle between the end straight blade curve and the X axis, that is, half of the angle between the two straight blades at the end, α = 10°; a is half of the blade tip width, a = b / 2-(LH 1 )·tan(α).

[0097] In step three, verify in Matlab whether the blade curve has a smooth transition and check the correctness of the blade curve model. In this embodiment, the mathematical model simulation software used is Matlab. Matlab not only has powerful numerical calculation capabilities, but also has powerful drawing functions, which can easily visualize data in multi-dimensional graphics. In the workpiece coordinate system, the mathematical expressions of the three-segment blade curve are programmed in the software using functions. After running the code, you can see a three-dimensional simulation diagram of the blade curve with arc transition. For details, please refer to Figure 5 .

[0098] In step 4, the grinding point P is defined as a point on the edge of the grinding surface of the grinding wheel, and the local coordinate system X is established based on the grinding point P. L Y L Z L The local coordinate system is obtained by rotation and translation transformation of the workpiece coordinate system; the origin O of the local coordinate system is located on the blade line, and the cutting plane of the blade is made through this point. The plane must pass through the center of the grinding wheel, and the radius of the grinding wheel diameter on the cutting plane is the real radius R of the grinding wheel. g ; Define the tangent direction of the blade curve as coordinate system X L , coordinate axis Y L It is in the normal direction of the blade curve, and the coordinate axis Z L It is on the blade surface; the local coordinate system is used to determine the relative positions of different parts of the grinding wheel machining tool, and to solve the grinding trajectory of the grinding wheel when grinding the blade surface. The coordinate system moves with the grinding point on the blade curve.

[0099] In step five, the grinding wheel used for grinding the ultrasonic tool is a CBN cup-type grinding wheel. The grinding method is to use the large end face of the bowl-type grinding wheel to grind the blade surface, and the upper and lower blade surfaces naturally form a blade; the grinding wheel center is defined as the geometric center of the grinding wheel grinding surface, and the posture of the grinding wheel grinding blade surface is defined through a specific grinding process method. Based on this grinding posture, the position of the grinding wheel center in the normal section coordinate system is solved.

[0100] In step six, the expression of the grinding wheel center in the workpiece coordinate system is obtained by coordinate conversion between the local coordinate system and the workpiece coordinate system, and the grinding trajectory of the grinding wheel about the smooth transition of the ultrasonic knife blade is expressed as follows:

[0101] (1) Parallel blade grinding track:

[0102]

[0103] Where T 1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system;

[0104] When parallel blade surface grinding is performed, the expression of the grinding wheel axis vector in the workpiece coordinate system is:

[0105]

[0106] Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system;

[0107] (2) Grinding trajectory of circular blade edge:

[0108]

[0109] Where T 1 is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; T' 2 , T 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system;

[0110] The expression of the grinding wheel axis vector in the workpiece coordinate system during arc blade grinding is:

[0111]

[0112] Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system;

[0113] (3) Grinding track of the end blade surface:

[0114]

[0115] Where T 1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 2 , T 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system;

[0116] When grinding the end blade surface, the expression of the grinding wheel axis vector in the workpiece coordinate system is:

[0117]

[0118] Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system.

[0119] like Figure 7 As shown, the present embodiment provides a structural improvement and grinding track innovation design system for an ultrasonic straight blade, including the following modules:

[0120] A module for the smooth transition model of the blade is proposed. A model for the smooth transition of the blade is proposed based on the analysis of the structure of the ultrasonic straight blade knife body. Specifically, the structure shape of the ultrasonic straight blade knife body is symmetrical up and down and left and right, the angle between the two blade lines on one side is 170°, and there is no smooth transition between the corresponding blade surfaces. After the improved design, the blade can have a smooth transition.

[0121] The module for establishing the model of smooth blade transition is to establish the workpiece coordinate system XYZ at the root center of the straight blade tool. The model of smooth blade transition is established in this coordinate system, including the mathematical models of the parallel blade curve, the arc blade curve and the end straight blade curve. Specifically, the workpiece coordinate system is established and fixed on the workpiece, the coordinate axis X coincides with the axis of the workpiece, and the directions of the coordinate axes Y and Z are determined by the right-hand rule. The coordinate system is used to describe the geometric parameters and geometric shape of the tool. The smooth transition blade curve established based on the workpiece coordinate system is as follows:

[0122] (1) Parallel blade curve:

[0123] (2) Arc blade curve:

[0124] (3) End straight edge curve:

[0125] Define the tool geometry parameters after arc transition: L1 is the parallel blade length, L 1 =H 1 -c;R t is the custom radius of the arc blade; c is R t The sine value of c = R t tan(α / 2); θ is the center angle of the arc segment of the tool, that is, the angle between the tangent of the arc blade and the X-axis direction, 0≤θ≤10°; L2 is the straight-line distance from the origin of the workpiece coordinate system to the end point of the arc blade, L 2 =H 1 +c·cos(α); α is the angle between the end straight blade curve and the X axis, that is, half of the angle between the two straight blades at the end, α = 10°; a is half of the blade tip width, a = b / 2-(LH 1 )·tan(α).

[0126] Verification module: Verify whether the blade curve has a smooth transition in Matlab and check the correctness of the blade curve model;

[0127] The coordinate system establishment module establishes the local coordinate system X based on the grinding moving point P according to the processing technology of the ultrasonic straight blade knife. L Y L Z L Specifically, the grinding point P is defined as a point on the edge of the grinding surface of the grinding wheel, and the local coordinate system X is established based on the grinding point P. L Y L Z L The local coordinate system is obtained by rotation and translation transformation of the workpiece coordinate system; the origin O of the local coordinate system is located on the blade line, and the cutting plane of the blade is made through this point. The plane must pass through the center of the grinding wheel, and the radius of the grinding wheel diameter on the cutting plane is the real radius R of the grinding wheel. g ; Define the tangent direction of the blade curve as coordinate system X L , coordinate axis Y L It is in the normal direction of the blade curve, and the coordinate axis Z L It is on the blade surface; the local coordinate system is used to determine the relative positions of different parts of the grinding wheel machining tool, and to solve the grinding trajectory of the grinding wheel when grinding the blade surface. The coordinate system moves with the grinding point on the blade curve.

[0128] The position calculation module calculates the position of the grinding wheel center in the local coordinate system according to the grinding posture of the grinding wheel, including the grinding wheel center position and the grinding wheel axis vector; specifically, the grinding wheel used for grinding ultrasonic tools is a CBN bowl-type grinding wheel, and the grinding method is to grind the blade surface with the large end surface of the bowl-type grinding wheel, and the upper and lower blade surfaces naturally form a blade; the grinding wheel center is defined as the geometric center of the grinding wheel grinding surface, and the posture of the grinding wheel grinding blade surface is defined through a specific grinding process method, and the position of the grinding wheel center in the normal section coordinate system is solved based on this grinding posture.

[0129] Output the grinding trajectory module of the smooth transition of the ultrasonic knife blade, obtain the expression of the grinding wheel center in the workpiece coordinate system through coordinate conversion, and obtain the grinding trajectory of the grinding wheel about the smooth transition of the ultrasonic knife blade. Specifically, the expression of the grinding wheel center in the workpiece coordinate system is calculated through the coordinate conversion between the local coordinate system and the workpiece coordinate system, and the grinding trajectory of the grinding wheel about the smooth transition of the ultrasonic knife blade is expressed as follows:

[0130] (1) Parallel blade grinding track:

[0131]

[0132] Where T 1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system;

[0133] When parallel blade surface grinding is performed, the expression of the grinding wheel axis vector in the workpiece coordinate system is:

[0134]

[0135] Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system;

[0136] (2) Grinding trajectory of arc blade edge:

[0137]

[0138] Where T 1 is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; T' 2 , T 3 is the rotation transformation matrix; [x LS y LS z LS ]T is the position of the grinding wheel center in the local coordinate system;

[0139] The expression of the grinding wheel axis vector in the workpiece coordinate system during arc blade grinding is:

[0140]

[0141] Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system;

[0142] (3) Grinding track of the end blade surface:

[0143]

[0144] Where T 1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 2 , T 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system;

[0145] When grinding the end blade surface, the expression of the grinding wheel axis vector in the workpiece coordinate system is:

[0146]

[0147] Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system.

[0148] The present invention conducts in-depth research on the structural improvement and grinding trajectory solution of ultrasonic straight-edge knives, providing a sufficient theoretical basis for the actual production and processing of such knives.

Claims

1. Structural improvement of ultrasonic straight blade and innovative design method of grinding trajectory, It is characterized in that The following steps are involved: Step 1: Based on the analysis of the structure of the ultrasonic straight blade, a model of blade smooth transition is proposed; specifically, in step 1, the angle between two adjacent straight blades is made into an angle bisector, and a point A is taken on the angle bisector, so that the distance from point A to the two straight blades is R t , with point A as the center of the circle R t Draw an arc with the radius, which intersects with the two straight blades at points B and C. The arc BC is the arc blade curve, the straight line from the end of the blade to point B is the end straight blade, and the straight line from the end of the blade to point C is the parallel blade. Step 2: Establish a workpiece coordinate system XYZ at the root center of the straight-edge knife, and establish a model of smooth transition of the blade in this coordinate system, including mathematical models of parallel blade curve, arc blade curve and end straight blade curve; Step 3: Verify whether the blade curve has a smooth transition and check the correctness of the blade curve model; Step 4: Establish a local coordinate system X based on the grinding moving point P according to the processing technology of the ultrasonic straight blade knife L Y L Z L ; Step 5, calculating the position of the grinding wheel center in the local coordinate system according to the grinding wheel grinding posture, including the grinding wheel center position and the grinding wheel axis vector; Step 6, obtaining the expression of the grinding wheel center in the workpiece coordinate system through coordinate transformation, and obtaining the grinding trajectory of the grinding wheel with smooth transition of the ultrasonic knife blade; In step 2, a workpiece coordinate system is established and fixed on the workpiece. The coordinate axis X coincides with the axis of the workpiece, and the directions of the coordinate axes Y and Z are determined by the right-hand rule. This coordinate system is used to describe the geometric parameters and geometric shape of the tool. The smooth transition blade curve established based on the workpiece coordinate system is as follows: (1) Parallel blade curve: (2) Arc blade curve: (3) End straight edge curve: Define the tool geometry parameters after arc transition: L1 is the parallel blade length, L 1 =H 1 -c;R t is the custom radius of the arc blade; c is R t The sine value of, c = R t tan(α2); θ is the center angle of the arc segment of the tool, that is, the angle between the tangent of the arc blade and the X-axis direction, 0≤θ≤10°; L2 is the straight-line distance from the origin of the workpiece coordinate system to the end point of the arc blade, L 2 =H 1 +c·cos(α); α is the angle between the end straight blade curve and the X axis, that is, half of the angle between the two straight blades at the end, α = 10°; a is half of the width of the blade tip, a = b2-(LH 1 )·tan(α); In step 4, the grinding point P is defined as a point on the edge of the grinding surface of the grinding wheel, and the local coordinate system X is established based on the grinding point P. L Y L Z L The local coordinate system is obtained by rotation and translation transformation of the workpiece coordinate system; the origin O of the local coordinate system is located on the blade line, and the cutting plane of the blade is made through this point. The plane must pass through the center of the grinding wheel, and the radius of the grinding wheel diameter on the cutting plane is the real radius R of the grinding wheel. g ; Define the tangent direction of the blade curve as coordinate system X L , coordinate axis Y L It is in the normal direction of the blade curve, and the coordinate axis Z L It is on the blade surface; the local coordinate system is used to determine the relative positions of different parts of the grinding wheel machining tool and to solve the grinding trajectory of the grinding wheel when grinding the blade surface. The coordinate system moves with the grinding point on the blade curve; In step six, the expression of the grinding wheel center in the workpiece coordinate system is obtained by coordinate conversion between the local coordinate system and the workpiece coordinate system, and the grinding trajectory of the grinding wheel about the smooth transition of the ultrasonic knife blade is expressed as follows: (1) Parallel blade grinding track: Among them, T 1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system; When parallel blade surface grinding is performed, the expression of the grinding wheel axis vector in the workpiece coordinate system is: Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system; (2) Grinding trajectory of circular blade edge: Among them, T 1 is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; T' 2 、T 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system; The expression of the grinding wheel axis vector in the workpiece coordinate system during arc blade grinding is: Among them, [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system; (3) Grinding track of the end blade surface: Among them, T 1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 2 、T 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system; When grinding the end blade surface, the expression of the grinding wheel axis vector in the workpiece coordinate system is: Among them, [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system.

2. According to the structural improvement and grinding track innovative design method of the ultrasonic straight blade according to claim 1, Features: In step 1, the structure shape of the ultrasonic straight blade knife body is symmetrical up and down and left and right, the angle between the two blade lines on one side is 170°, and there is no smooth transition between the corresponding blade surfaces.

3. According to the structural improvement and grinding track innovative design method of the ultrasonic straight blade according to claim 1, Features: In step three, Matlab is used to verify whether the blade curve has a smooth transition and to check the correctness of the blade curve model.

4. According to claim 1, the method for improving the structure of the ultrasonic straight blade and innovating the design of the grinding track, Features: In step five, the grinding wheel used for grinding the ultrasonic tool is a CBN cup-type grinding wheel. The grinding method is to use the large end face of the bowl-type grinding wheel to grind the blade surface, and the upper and lower blade surfaces naturally form a blade; the grinding wheel center is defined as the geometric center of the grinding wheel grinding surface, and the posture of the grinding wheel grinding blade surface is defined through a specific grinding process method. Based on this grinding posture, the position of the grinding wheel center in the normal section coordinate system is solved.

5. Structural improvement of ultrasonic straight blade and innovative design system of grinding track, It is characterized in that Includes the following modules: The module for proposing a blade smooth transition model proposes a blade smooth transition model based on the analysis of the blade structure of the ultrasonic straight blade. Specifically, in the module for proposing a blade smooth transition model, the angle between two adjacent straight blades is made into an angle bisector, and a point A is taken on the angle bisector, so that the distance from point A to the two straight blades is R. t , with point A as the center of the circle R t Draw an arc with the radius, which intersects with the two straight blades at points B and C. The arc BC is the arc blade curve, the straight line from the end of the blade to point B is the end straight blade, and the straight line from the end of the blade to point C is the parallel blade. The blade smooth transition model establishment module establishes a workpiece coordinate system XYZ at the root center of the straight blade tool, and establishes a blade smooth transition model in this coordinate system, including mathematical models of parallel blade curves, arc blade curves and end straight blade curves; specifically, in the blade smooth transition model establishment module, a workpiece coordinate system is established and fixed on the workpiece, the coordinate axis X coincides with the axis of the workpiece, and the directions of the coordinate axes Y and Z are determined by the right-hand rule. The coordinate system is used to describe the geometric parameters and geometric shape of the tool; the blade curve of smooth transition established based on the workpiece coordinate system is as follows: (1) Parallel blade curve: (2) Arc blade curve: (3) End straight edge curve: Define the tool geometry parameters after arc transition: L1 is the parallel blade length, L 1 =H 1 -c;R t is the custom radius of the arc blade; c is R t The sine value of, c = R t tan(α2); θ is the center angle of the arc segment of the tool, that is, the angle between the tangent of the arc blade and the X-axis direction, 0≤θ≤10°; L2 is the straight-line distance from the origin of the workpiece coordinate system to the end point of the arc blade, L 2 =H 1 +c·cos(α); α is the angle between the end straight blade curve and the X axis, that is, half of the angle between the two straight blades at the end, α = 10°; a is half of the width of the blade tip, a = b2-(LH 1 )·tan(α); Verification module, verifying whether the blade curve has a smooth transition and checking the correctness of the blade curve model; The coordinate system establishment module establishes the local coordinate system X based on the grinding moving point P according to the processing technology of the ultrasonic straight blade knife. L Y L Z L Specifically, in the coordinate system establishment module, the grinding point P is defined as a point on the edge of the grinding surface of the grinding wheel, and the local coordinate system X is established based on the grinding point P. L Y L Z L The local coordinate system is obtained by rotation and translation transformation of the workpiece coordinate system; the origin O of the local coordinate system is located on the blade line, and the cutting plane of the blade is made through this point. The plane must pass through the center of the grinding wheel, and the radius of the grinding wheel diameter on the cutting plane is the real radius R of the grinding wheel. g ; Define the tangent direction of the blade curve as coordinate system X L , coordinate axis Y L It is in the normal direction of the blade curve, and the coordinate axis Z L It is on the blade surface; the local coordinate system is used to determine the relative positions of different parts of the grinding wheel machining tool and to solve the grinding trajectory of the grinding wheel when grinding the blade surface. The coordinate system moves with the grinding point on the blade curve; The position calculation module calculates the position of the grinding wheel center in the local coordinate system according to the grinding wheel grinding posture, including the grinding wheel center position and the grinding wheel axis vector; The module for outputting the grinding trajectory of the smooth transition of the ultrasonic knife blade obtains the expression of the grinding wheel center in the workpiece coordinate system through coordinate conversion, and obtains the grinding trajectory of the grinding wheel with respect to the smooth transition of the ultrasonic knife blade; specifically, in the module for outputting the grinding trajectory of the smooth transition of the ultrasonic knife blade, the expression of the grinding wheel center in the workpiece coordinate system is obtained through the coordinate conversion calculation between the local coordinate system and the workpiece coordinate system, and the grinding trajectory of the grinding wheel with respect to the smooth transition of the ultrasonic knife blade is expressed as follows: (1) Parallel blade grinding track: Among them, T 1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system; When parallel blade surface grinding is performed, the expression of the grinding wheel axis vector in the workpiece coordinate system is: Where [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system; (4) Grinding trajectory of arc blade edge: Among them, T 1 is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; T' 2 , T 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system; The expression of the grinding wheel axis vector in the workpiece coordinate system during arc blade grinding is: Among them, [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system; (5) Grinding track of the end blade surface: Among them, T 1 T is the translation transformation matrix from the workpiece coordinate system to the local coordinate system; 2 , T 3 is the rotation transformation matrix; [x LS y LS z LS ] T is the position of the grinding wheel center in the local coordinate system; When grinding the end blade surface, the expression of the grinding wheel axis vector in the workpiece coordinate system is: Among them, [X tw2 Y tw2 Z tw2 ] T is the expression of the grinding wheel axis vector in the local coordinate system.

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