阅读说明：本技术 一种剪切角在线测量系统及方法 (Shear angle on-line measurement system and method ) 是由 张小明 邓志豪 张东 丁汉 于 2019-09-20 设计创作，主要内容包括：本发明属于金属切削加工领域,并具体公开了一种剪切角在线测量系统及方法,其包括刀具、透光薄片、激光扫描仪和车床滑台,其中,所述刀具装夹在所述车床滑台上,所述透光薄片固定在所述刀具上方,所述激光扫描仪安装在所述透光薄片上方,并固定在所述车床滑台上；测量时,所述刀具对工件进行切削,所述透光薄片在工件的切屑形成时将切屑压在透光薄片和刀具之间,所述激光扫描仪透过透光薄片扫描该切屑厚度方向的外轮廓,从而得到切屑厚度,进而通过切屑厚度得到剪切角。本发明在切削实验过程中完成剪切角测量,结构简单,安装容易,在一般的车床上即可使用,同时测量结果准确可靠。(The invention belongs to the field of metal cutting machining, and particularly discloses a shear angle on-line measuring system and a shear angle on-line measuring method, wherein the shear angle on-line measuring system comprises a cutter, a light-transmitting sheet, a laser scanner and a lathe sliding table, wherein the cutter is clamped on the lathe sliding table, the light-transmitting sheet is fixed above the cutter, and the laser scanner is arranged above the light-transmitting sheet and fixed on the lathe sliding table; during measurement, the cutter cuts a workpiece, chips are pressed between the light-transmitting sheet and the cutter when the chips of the workpiece are formed, the laser scanner scans the outer contour of the chip in the thickness direction through the light-transmitting sheet, the chip thickness is obtained, and then the shearing angle is obtained through the chip thickness. The invention completes the measurement of the shearing angle in the cutting experiment process, has simple structure and easy installation, can be used on a common lathe, and has accurate and reliable measurement result.)

1. The on-line shear angle measuring system is characterized by comprising a cutter (3), a light-transmitting sheet (2), a laser scanner (7) and a lathe sliding table (4), wherein the cutter (3) is clamped on the lathe sliding table (4); the light-transmitting sheet (2) is fixed above the cutter (3); the laser scanner (7) is arranged above the light-transmitting sheet (2) and is fixed on the lathe sliding table (4);

during measurement, the cutter (3) cuts a workpiece (1), chips are pressed between the light-transmitting sheet (2) and the cutter (3) by the light-transmitting sheet (2) when the chips of the workpiece (1) are formed, the outer contour of the chips in the thickness direction is scanned by the laser scanner (7) through the light-transmitting sheet (2), so that the chip thickness is obtained, and further, a shearing angle is obtained through the chip thickness.

2. The shear angle on-line measurement system of claim 1, wherein the light-transmitting sheet (2) is preferably a sapphire sheet.

3. The shear angle on-line measuring system according to claim 1, wherein the thickness of the light-transmitting sheet (2) is 2mm to 10 mm.

4. The shear angle on-line measuring system according to claim 1, wherein the distance between the lower surface of the transparent sheet (2) and the upper surface of the cutter (3) is 5mm to 15 mm.

5. The shear angle on-line measuring system according to claim 1, wherein the distance between the edge of the transparent sheet (2) and the surface of the workpiece (1) is 2mm to 5 mm.

6. The on-line shear angle measuring system of claim 1, characterized in that the laser scanner (7) is fixed on the lathe carriage (4) by means of a fine tuning platform.

7. A shear angle on-line measuring system according to claim 6, characterized in that the fine-tuning platform comprises a rotary fine-tuning platform (8) and a displacement fine-tuning platform (9) which are movably connected, the laser scanner (7) is installed at the lower end of the rotary fine-tuning platform (8), and the displacement fine-tuning platform (9) is fixed on the lathe sliding table (4).

8. A method for on-line measurement of shear angle, implemented using a system according to any of claims 1-7, comprising the steps of:

s1 cutting tool (3) with a predetermined cutting layer thickness h_DCutting a workpiece (1), wherein the light-transmitting sheet (2) presses chips between the light-transmitting sheet (2) and a cutter (3) when the chips of the workpiece (1) are formed;

s2 the laser scanner (7) scans the outer contour of the chip in the thickness direction through the light-transmitting sheet (2) to obtain the chip thickness h_chAnd further calculating to obtain a shear angle phi through the following formula to finish the online measurement of the shear angle:

wherein, γ₀Is the rake angle of the cutter (3).

9. The method for on-line measurement of a shear angle according to claim 8, wherein the cutting speed is 30m/min to 210m/min and the feed rate is 0.1mm to 0.15mm when the tool (3) cuts the workpiece (1).

10. The method for on-line measurement of shear angle of claim 8, wherein the predetermined cutting layer thickness h_DIs 2 mm-4 mm.

Technical Field

The invention belongs to the field of metal cutting machining, and particularly relates to a shear angle on-line measuring system and method.

Background

The shearing angle is the included angle between the shearing surface and the cutting speed direction, indicates the shearing direction of the cutting unit, has important influence on metal deformation, cutting force and cutting temperature in cutting, and is a quite important parameter in the metal cutting process. The larger the shear angle is, the smaller the cutting deformation is; the smaller the shear angle, the greater the cutting deformation. Many scholars have conducted a great deal of research on the problem of shear angle according to the theory of elastoplasticity and the like, and attempt to establish the rake angle gamma of the cutter₀The friction angle beta and the shearing angle phi on the contact surface of the cutter and the chip are theoretical relational expressions, and a plurality of formulas for calculating the shearing angle are deduced, wherein the following two shearing angle formulas are commonly used at present:

(1) merchant's formula: the Merchant model carries out quantitative analysis on the shearing angle for the first time, the form is simple and easy to calculate, the shearing angle is obtained by assuming that the shearing surface is an ideal plastic zone and the shearing stress is a constant according to the principle that the shearing surface occurs in the direction with the minimum energy consumption of the unit cutting volume and carrying out a series of deductions₀Pi/2, where phi is the shear angle, beta is the friction angle, and gamma₀Is the front angle of the cutter;

(2) lee and Shaffer equation: lee and Shaffer models firstly use the principle of slip lines to analyze the cutting problem, and derive phi pi/4- (beta-gamma) according to the principle that the included angle between the direction of the maximum shearing stress of the material and the direction of the main stress of the material is pi/4₀) Where phi is the shear angle, beta is the friction angle, gamma₀Is the tool rake angle.

For the two models, the Merchant model does not take the stress and strain relation of a shear zone into consideration; the Lee and Shaffer model ignores the work hardening phenomenon of the material, both prediction models have certain deviation from the actual situation, and can only qualitatively reflect the influence of the front angle and the friction angle of the cutter on the shearing angle; furthermore, both models are based on the theory of static deformation of the material, and the shear strain of the material in the slip region is generally 10 in the actual cutting process²S to 10⁴Such high strain rates are very different from static deformation. Thus, build aA platform for dynamically calculating the shear angle is highly desirable.

As the performance of industrial cameras is more and more excellent, the corresponding Digital Imaging Correlation (DIC) technology is more and more mature, and the image processing and DIC technology is more and more used in the field of machining. DIC technique is through shooting two frames of images in the cutting process, divide the deformation field into different size analysis area, trace and match the pixel characteristic point on the surface of the object, carry on "correlation match" to realize through comparing the analysis area before and after deforming, this method has good precision to the displacement measurement in the level, for right angle cutting, if adopt 2D camera combine DIC technique, although can observe the chip and separating process of the work piece basal body in the right angle cutting, then calculate the line of the point with the biggest strain rate in the shear zone through DIC technique to find out the shear angle, but this method is first under the unstable situation of light source, the result of the matching algorithm is too stable; secondly, only the in-plane displacement can be measured, and the out-of-plane displacement cannot be calculated, so that the method is not suitable for bevel cutting; thirdly, the high-speed camera is expensive and difficult to install and use. If a binocular high-speed camera is applied to measurement of the shearing angle, chips in images shot by a left camera and a right camera need to be matched, then a series of image processing algorithms are used for extracting the chips, three-dimensional space coordinates of all points on the surface of the chips are restored and fitted to obtain the required chip thickness, and the shearing angle is calculated.

Therefore, the method for measuring the shearing angle on line, which is convenient to use and high in precision, is found, is applied to analysis of relevant parameters in the cutting process, provides a new method and thought for the research of the integrity of the machined surface, and has important significance.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides a shear angle on-line measurement system and a shear angle on-line measurement method, and aims to guide cuttings through a transparent sheet additionally arranged above a cutter during a cutting experiment, measure the thickness of the cuttings through the transparent sheet by a laser scanner, further calculate a shear angle, realize real-time on-line measurement of the shear angle, and have the advantages of simple system structure, easy installation and high measurement precision.

In order to achieve the above object, according to one aspect of the present invention, an online shear angle measuring system is provided, which includes a tool, a transparent sheet, a laser scanner, and a lathe slide, wherein the tool is clamped on the lathe slide; the light-transmitting sheet is fixed above the cutter; the laser scanner is arranged above the light-transmitting sheet and fixed on the lathe sliding table;

during measurement, the cutter cuts a workpiece, chips are pressed between the light-transmitting sheet and the cutter when the chips of the workpiece are formed, the laser scanner scans the outer contour of the chip in the thickness direction through the light-transmitting sheet, the chip thickness is obtained, and then the shearing angle is obtained through the chip thickness.

Further preferably, the light-transmitting sheet is preferably a sapphire sheet.

More preferably, the thickness of the light-transmitting sheet is 2mm to 10 mm.

More preferably, the distance between the lower surface of the light-transmitting sheet and the upper surface of the cutter is 5mm to 15 mm.

More preferably, the distance between the edge of the light-transmitting sheet and the surface of the workpiece is 2mm to 5 mm.

Preferably, the laser scanner is fixed on the lathe sliding table through a fine adjustment platform.

As further preferred, fine setting platform includes swing joint's rotatory fine setting platform and displacement fine setting platform, rotatory fine setting platform lower extreme installation laser scanner, the displacement fine setting platform is fixed on the lathe slip table.

According to another aspect of the present invention, an online shear angle measuring method is provided, which is implemented by using the above system, and includes the following steps:

s1 cutting tool with preset cutting layer thickness h_DCutting the workpiece to obtain a transparent sheetPressing the chips between the transparent sheet and the cutter as the chips of the article are formed;

s2 laser scanner scans the outer contour of the chip in the thickness direction through the light-transmitting sheet to obtain the chip thickness h_chAnd further calculating to obtain a shear angle phi through the following formula to finish the online measurement of the shear angle:

wherein, γ₀Is the tool rake angle.

More preferably, the cutting speed is 30m/min to 210m/min and the feed rate is 0.1mm to 0.15mm when the tool is used for cutting a workpiece.

Preferably, the predetermined cutting layer thickness h_DIs 2 mm-4 mm.

Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

1. the invention adds the transparent sheet above the cutter, when the cutting chips are formed, the cutting chips are pressed in the gap between the transparent sheet and the front cutter surface of the cutter, so that the cutting chips can not curl and flow out along the guide direction, thereby the laser scanner can accurately obtain the thickness of the cutting chips, and further the shearing angle is calculated.

2. The system can complete the measurement of the shear angle on line in real time along with the cutting, and the thickness of the chips is measured in the cutting experiment process, so that the reading error of the measurement by using a vernier caliper after the experiment is finished is avoided.

3. The invention sets proper cutting parameters, avoids overlarge extrusion force generated by chip outflow on the transparent sheet, and can completely and clearly obtain the outline of the chip.

Drawings

FIG. 1 is a schematic structural diagram of an on-line shear angle measurement system according to an embodiment of the present invention;

FIG. 2 is a diagram of an embodiment of the present invention illustrating an on-line shear angle measurement system;

FIG. 3 is a schematic view of a right angle machined workpiece according to an embodiment of the present invention;

fig. 4 is a schematic view of the geometrical relationship between the cutting thickness and the shearing angle.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein: 1-workpiece, 2-light-transmitting sheet, 3-cutter, 4-lathe sliding table, 5-magnetic seat, 6-clamp, 7-laser scanner, 8-rotary fine adjustment platform and 9-displacement fine adjustment platform.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The shear angle on-line measuring system provided by the embodiment of the invention is shown in fig. 1 and 2, and comprises a cutter 3, a magnetic seat 5, a light-transmitting sheet 2, a laser scanner 7, a fine adjustment platform and a lathe sliding table 4, wherein: the cutter 3 is clamped on the lathe sliding table 4; the magnetic seat 5 is fixedly adsorbed on the lathe sliding table 4, a clamp 6 is arranged on the magnetic seat, and the light-transmitting sheet 2 is positioned above the cutter 3 and is clamped on the clamp 6 through a set screw; laser scanner 7 is located printing opacity thin slice 2 top, and the fine setting platform includes rotatory fine setting platform 8 and displacement fine setting platform 9, and laser scanner 7 is installed at rotatory fine setting platform 8 lower extreme, and rotatory fine setting platform 8 is installed on lathe slip table 4 through displacement fine setting platform 9, and displacement fine setting platform 9 is used for adjusting laser scanner 7's position, and rotatory fine setting platform 8 is used for adjusting laser scanner 7's scanning angle.

Specifically, the visible light emitted from the laser scanner 7 has a wavelength within a wavelength range that the light-transmitting sheet 2 can transmit, and preferably, the laser scanner 7 is a line laser profile scanner and the light-transmitting sheet 2 is a sapphire sheet.

Further, the thickness of the light-transmitting sheet 2 is 2 mm-10 mm; during a cutting experiment, the distance between the lower surface of the transparent sheet 2 and the upper surface of the cutter 3 is 5-15 mm, and the distance between the edge of the transparent sheet 2 and the surface of the workpiece 1 to be cut is 2-5 mm.

The method for measuring the shear angle on line is realized by adopting the system, and specifically comprises the following steps:

s1 cutting tool 3 according to the preset cutting layer thickness h_DCutting the workpiece 1, wherein the light-transmitting sheet 2 presses the chips between the light-transmitting sheet 2 and the cutter 3 when the chips of the workpiece 1 are formed, so that the chips stretch and do not curl and flow out along the guiding direction;

s2 laser light with a certain wavelength emitted from the laser scanner 7 passes through the light-transmitting sheet 2 to scan the outer contour in the chip thickness direction, thereby obtaining the chip thickness h_ch(ii) a Further, from the geometric relationship shown in fig. 4, the thickness deformation coefficient ξ:

wherein, γ₀The front angle of the cutter 3, OM is a shearing plane, and phi is a shearing angle to be solved; and then obtaining a shear angle phi as shown in the following formula, thereby completing the online measurement of the shear angle:

specifically, the position of the light-transmitting sheet 2 is adjusted through a guide rod of the magnetic seat 5, and the position and the angle of the laser scanner are adjusted through the fine adjustment device, so that the length direction of laser emitted by the laser scanner is parallel to the width direction of chips, and the laser is guaranteed to penetrate through the sapphire sheet and hit at the position where the chips are just formed.

Furthermore, during cutting, the cutting speed is 30-210 m/min, the feed rate is 0.1-0.15 mm, and the thickness h of the cutting layer is_D2 mm-4 mm, and excessive extrusion force on the transparent sheet caused by chip outflow is avoided.

The shear angle measuring system and the shear angle measuring method are suitable for various conditions such as right-angle cutting, oblique-angle cutting and the like, and can be used for measuring the shear angle under different cutting parameters on line.

The following are specific examples: