阅读说明：本技术 一种去除拉伸试样件表面加工应力的设备及其方法 (Device and method for removing machining stress on surface of tensile sample piece ) 是由 刘锦韬 何海燕 赵军 于 2019-09-28 设计创作，主要内容包括：本发明公开了一种去除拉伸试样件表面机械加工应力的设备及其方法,是一种以加工过程中尽量保证材料原始状态的低线速切削加工法,在提高同批试拉伸样件的可靠性、一致性的同时,提高了拉伸试样件制备生产效率的专用设备。本发明的特点：1、由可编程控制器控制磨削过程中第一平移运动副、第二平移运动副运动与第三平移运动副相配合,使得磨头与拉伸试样件加工成空间轴线正交表面相切接触状态,实现去除拉伸试样件表面环状向纹理及加工应力的自动化机械加工；2、压力恒定装置使磨头在加工过程中对工件始终在第三平移运动副运动方向保持恒定压力,恒定压力补偿了柔性磨头的加工损耗及尺寸误差所造成的磨削量不均。(The invention discloses equipment and a method for removing mechanical processing stress on the surface of a tensile sample piece, and the equipment and the method are special equipment which can ensure the original state of a material as much as possible in the processing process by a low linear speed cutting processing method, improve the reliability and consistency of the tensile sample pieces tested in the same batch and improve the preparation production efficiency of the tensile sample pieces. The invention has the characteristics that: 1. the programmable controller controls the first translation kinematic pair, the second translation kinematic pair and the third translation kinematic pair to be matched in the grinding process, so that the grinding head and the tensile sample piece are processed into a tangential contact state of the orthogonal surface of the spatial axis, and the automatic mechanical processing for removing the annular texture and the processing stress on the surface of the tensile sample piece is realized; 2. the pressure constant device enables the grinding head to keep constant pressure on the workpiece in the movement direction of the third translation motion pair all the time in the machining process, and the constant pressure compensates the machining loss of the flexible grinding head and uneven grinding amount caused by dimensional errors.)

1. The equipment for removing the processing stress on the surface of the tensile sample piece is characterized in that: comprises that

A bed body;

the X-axis guide rail is arranged on the lathe bed;

the X-axis servo sliding block moves along the X-axis guide rail;

the first driving device drives the X-axis servo slide block to move along the X-axis guide rail;

the Y-axis guide rail base is fixed on the X-axis servo sliding block;

the Y-axis guide rail is arranged on the Y-axis guide rail base;

the Y-axis servo sliding block moves along the Y-axis guide rail, and a main shaft base, a grinding head electric main shaft, a chuck and a grinding head are arranged on the Y-axis servo sliding block;

the second driving device drives the Y-axis servo sliding block to move along the Y-axis guide rail;

the Y' axis guide rail is arranged on the lathe bed and is parallel to the Y axis guide rail;

the sample clamping mechanism moves along the Y' -axis guide rail;

the one-way cylinder piston is arranged on the lathe bed and applies constant thrust to the sample clamping mechanism in the Y-axis direction.

2. The apparatus for removing machining stress from the surface of a tensile test piece of claim 1, wherein: the sample clamping mechanism comprises

A Y 'axis guide rail slider moving along the Y' axis guide rail;

the rail frame is arranged on the Y '-axis guide rail sliding block and moves along with the Y' -axis guide rail sliding block;

a rotary feed assembly;

the axis of a main shaft of the rotary feeding assembly is collinear with the axis of the workpiece jacking assembly and is parallel to the X axis, and the axis of the workpiece after being clamped and positioned is parallel to the X axis.

3. The apparatus for removing machining stress from the surface of a tensile test piece of claim 2, wherein: the rotary feeding assembly comprises a headstock, a headstock main shaft with a tip at the front end, a bearing, a thrust bearing, a coupler and an A-axis servo motor; the headstock is fixed on the track frame.

4. The apparatus for removing machining stress from the surface of a tensile test piece of claim 2, wherein: the workpiece jacking assembly comprises a tailstock, a tailstock centre part, a bidirectional cylinder and a bidirectional cylinder piston; the tailstock center part comprises a tailstock center seat, a center, a bearing and a thrust bearing; the tailstock moves and positions on the track frame.

5. The apparatus for removing machining stress from the surface of a tensile test piece according to any one of claims 1 to 4, wherein: the first driving device comprises an X-axis servo motor, a threaded rod and a threaded hole formed in the X-axis servo sliding block, the X-axis servo motor drives the threaded rod to rotate, and the threaded rod is matched with the threaded hole of the X-axis servo sliding block.

6. The apparatus for removing machining stress from the surface of a tensile test piece according to any one of claims 1 to 4, wherein: the second driving device comprises a Y-axis servo motor, a threaded rod and a threaded hole formed in the Y-axis servo sliding block, the Y-axis servo motor drives the threaded rod to rotate, and the threaded rod is matched with the threaded hole of the Y-axis servo sliding block.

7. The apparatus for removing machining stress from the surface of a tensile test piece according to any one of claims 1 to 4, wherein: the travel control device also comprises a first travel proximity switch and a second travel proximity switch; the first stroke proximity switch is arranged at the starting position of the stroke of the sample clamping mechanism, and the second stroke proximity switch is arranged at the ending position of the stroke of the sample clamping mechanism.

Technical Field

The invention belongs to the field of tensile sample piece processing, and particularly relates to equipment for removing processing stress on the surface of a tensile sample piece.

Background

In the field of aviation material testing, most of material tensile test samples belong to shaft type rotary machining parts, including turning and grinding machining (cutting speed, turning: about 50-300 m/min, grinding: about 1000-2000 m/min) of an excircle and belong to machining tracks which are orthogonal with an axis in space, so that annular machining lines and corresponding machining stress layers are generated.

According to related researches, the method comprises the following steps: the cutting layer comprises three different regions, namely a highly deformed nanostructured surface layer, a less deformed sub-surface layer and an unaffected matrix layer. The subsurface layer is driven by mechanical heat released by the machining, causing plasticity and crystal refinement by excessive shear forces to act on the cutting surface. Cutting, in which the residual stress is gradually changed from compressive stress to tensile stress along with the increase of the cutting speed in the cutting direction; however, compressive stress always remains in the feeding direction, and this compressive stress is perpendicular to the stretching direction.

The method comprises the steps of cylindrical grinding and possibly generating burns and annular cracks for processing the shaft type tensile sample piece, wherein the burns and the annular cracks are sensitive to stress concentration like sharp-angled notches and cracks, so that the fatigue strength of the part is influenced. The cracks and the stress which are vertical to the stretching direction all have adverse effects on the stretching physical mechanical property index test of the stretching sample, so that the test data can not truly represent the actual performance of the material.

The general processing method in the industry is that 0.01-0.02mm is reserved in the diameter direction according to the tolerance upper limit when a tensile sample piece is processed, then the axial grinding is manually carried out on the use area of the tensile sample piece by using 800-2000# abrasive paper in a manual mode, the large deformation nano-structure surface stress layer with the thickness of about 0.01-0.02mm is removed, and then the tensile (creep) performance test is carried out. Such operations are inefficient, labor intensive, and poor in sample stability and consistency.

The invention aims to solve the problems, and designs a device and a method for removing the processing stress on the surface of a tensile sample piece, which ensure the authenticity of the original material state as much as possible, improve the reliability and consistency of tensile sample pieces tested in the same batch, and improve the production efficiency of tensile sample piece preparation.

Disclosure of Invention

The invention aims to solve the technical problem of a special device and a method for removing a nano-structure surface stress layer with a large deformation surface in a working area of a shaft tensile sample piece.

In order to solve the problems, the technical scheme of the invention is that,

a device for removing the surface processing stress of a tensile sample piece comprises

A bed body;

the X-axis guide rail is arranged on the lathe bed;

the X-axis servo sliding block moves along the X-axis guide rail;

the first driving device drives the X-axis servo slide block to move along the X-axis guide rail;

the Y-axis guide rail base is fixed on the X-axis servo sliding block;

the Y-axis guide rail is arranged on the Y-axis guide rail base;

the Y-axis servo sliding block moves along the Y-axis guide rail, and a main shaft base, a grinding head electric main shaft, a chuck and a grinding head are arranged on the Y-axis servo sliding block;

the second driving device drives the Y-axis servo sliding block to move along the Y-axis guide rail;

the Y' axis guide rail is arranged on the lathe bed and is parallel to the Y axis guide rail;

the sample clamping mechanism moves along the Y' -axis guide rail;

the one-way cylinder piston is arranged on the lathe bed and applies constant thrust to the sample clamping mechanism in the opposite direction of the Y axis.

Further, the sample clamping mechanism comprises

A Y 'axis guide rail slider moving along the Y' axis guide rail;

the rail frame is arranged on the Y '-axis guide rail sliding block and moves along with the Y' -axis guide rail sliding block;

a rotary feed assembly;

the axis of a main shaft of the rotary feeding assembly is collinear with the axis of the workpiece jacking assembly and is parallel to the X axis, and the axis of the workpiece after being clamped and positioned is parallel to the X axis.

Furthermore, the rotary feeding assembly comprises a headstock, a headstock main shaft with a tip at the front end, a bearing, a thrust bearing, a coupling and an A-axis servo motor; the headstock is fixed on the track frame.

Furthermore, the workpiece jacking assembly comprises a tailstock, a tailstock centre part, a bidirectional cylinder and a bidirectional cylinder piston; the tailstock center part comprises a tailstock center seat, a center, a bearing and a thrust bearing; the tailstock moves and positions on the track frame.

Furthermore, first drive arrangement includes X axle servo motor, threaded rod and sets up the screw hole of X axle servo slider, X axle servo motor drive the threaded rod is rotatory, the threaded rod with the screw hole cooperation of X axle servo slider.

Furthermore, the second driving device comprises a Y-axis servo motor, a threaded rod and a threaded hole formed in the Y-axis servo sliding block, the Y-axis servo motor drives the threaded rod to rotate, and the threaded rod is matched with the threaded hole of the Y-axis servo sliding block.

Further, the device also comprises a first travel proximity switch and a second travel proximity switch; the first stroke proximity switch is arranged at the starting position of the stroke of the sample clamping mechanism, and the second stroke proximity switch is arranged at the ending position of the stroke of the sample clamping mechanism.

The invention has the beneficial effects that:

1. the original processing lines and the surface hardening layer are processed and removed in the grinding direction perpendicular to the annular processing lines generated by the early-stage processing of the axial tensile sample, meanwhile, new processing stress is not generated by low-speed cutting, premature failure fracture caused by stress concentration problems caused by cracks perpendicular to the tensile direction is particularly avoided, and the axial tensile performance index of the material is truly characterized in the test. The full-automatic machining for removing the machining stress on the surface of the tensile sample piece is realized, the working efficiency is improved, the labor intensity of workers is reduced, the stability of the sample piece is ensured, and the condition of poor consistency of the sample piece is avoided;

2. the grinding head always keeps constant pressure on a workpiece in the Y-axis direction in the machining process, and the constant pressure compensates the machining loss of the flexible grinding head and uneven grinding amount caused by dimension errors.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention.

FIG. 1 is a schematic diagram of the machining motion of the grinding head and the sample piece of the present invention;

FIG. 2 is a schematic diagram of the motion control of the programmable controller of the present invention;

FIG. 3 is a signal state diagram of a first travel proximity switch and a second travel proximity switch;

FIG. 4 is a schematic structural diagram of an embodiment of the present invention;

FIG. 5 is a schematic diagram of the coordinate position relationship and the movement of the numerical control servo axis according to the embodiment of the present invention;

FIG. 6 is a schematic left side view of an embodiment of the present invention;

FIG. 7 is a schematic A-A cross-sectional view of an embodiment of the present invention;

FIG. 8 is a cross-sectional view of FIG. B-B illustrating an embodiment of the present invention;

FIG. 9 is a schematic E-E cross-sectional view of an embodiment of the present invention;

the grinding head device comprises a track frame 1, a tail frame 2, a bidirectional cylinder 3, a tensile sample piece 4, a lathe bed 5, a base of a Y servo shaft guide rail 6, a grinding head spindle base 7, a grinding head electric spindle 8, a unidirectional cylinder piston 9, a unidirectional cylinder 10, a bidirectional cylinder piston 11, a tail tip seat 12, a tip 13, a bearing 14, a thrust bearing 15, a head frame 16, a head frame 17, a head frame spindle 18, an A shaft servo motor 19, a coupler 20, a Y 'shaft guide rail 20, an X shaft guide rail 21, a Y' shaft guide rail slider 23, a Y shaft guide rail 24, a Y shaft servo slider 25, an X shaft servo slider 26, an X shaft servo motor 27, a Y shaft servo motor 28, a servo motor seat 29, a grinding head 30, a first stroke proximity switch 31, a second stroke proximity switch 32, an X shaft lead screw 33, a Y shaft lead screw 34 and a chuck.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

As shown in fig. 2 and 4

A device for removing the processing stress on the surface of a tensile sample piece belongs to mechanical, electrical and gas integrated equipment. At least 3-axis (XYA) motion controller control, which comprises an electric control system (comprising a programmable controller with an HMI interface, a servo driver, a servo motor, a travel proximity switch, a conventional electrical element and the like), a pneumatic system (comprising a precision pressure regulating valve, a manual reversing valve, a barometer, a two-way cylinder, a one-way cylinder and other pneumatic elements) and a machine body 5 of a mechanical system, a (longitudinal) X-axis guide rail 21 on the machine body 5, an X-axis servo slide block 25 and an X-axis servo motor 26 on the longitudinal X-axis guide rail 21, a (transverse) Y '-axis guide rail 20 on the machine body, a sample clamping mechanism capable of transversely floating on the Y' -axis guide rail, a Y-axis guide rail base 6 and a Y-axis servo motor 27 which are superposed on the X-axis servo slide block 25, and a (transverse) Y-axis guide rail 23, a Y-axis servo slide block 24 and a main shaft base 7 fixed on the Y-axis, a grinding head electric main shaft 8 arranged on the grinding head main shaft base 7, and a clamping head 34 fixed at the lower end of the grinding head electric main shaft 8; a flexible grinding head 29 with the diameter of 5-20 and the like is clamped on the chuck.

The principle of the machining movement is shown in figure 1,

the machining motion of the equipment is implemented by grinding head rotation main motion Cp, workpiece rotation feed Cf 2 rotation motion pairs, grinding head feed motion Xf and Yf vertical direction motion and workpiece pressure F action of the grinding head in Y direction, the lower end of a sample clamping mechanism for fixing the workpiece can move at least 3 translation motion pairs in Y 'F parallel to Yf feed direction under the action of F', and the mechanical structure of more than 5 motion pairs is needed to execute, so that the phase cutting method (rotary cutting method) machining of the workpiece surface is completed, and the 0.01-0.02 stress layer of the surface of the annular machining pattern of the tensile sample piece (hereinafter, all referred to as the workpiece) is removed.

The sample clamping mechanism consists of three parts, namely a track frame part, a rotary feeding assembly fixed on the track frame part and a workpiece jacking assembly which can move along a track on the track frame part and is positioned, so as to complete the functions of positioning, clamping and rotary feeding of the workpiece.

The rotary feeding assembly, shown in fig. 9, is composed of a headstock 16, a headstock spindle 17 with a tip at the front end, a bearing 14, a thrust bearing 15, a coupling 19, and an a-axis servo motor 18; the rotary feed assembly is fixed on the track frame 1 by a headstock 16. A servo motor 18 of an A shaft drives a headstock main shaft 17 to rotate through a coupling 19, and the friction force between the tip of the front end of the headstock main shaft 17 and the center hole of the end part of the workpiece 4 drives the workpiece to perform indexing and rotating actions.

The workpiece jacking assembly consists of a tailstock 2, a tailstock center part, a bidirectional cylinder 3 and a bidirectional cylinder piston 11; the tailstock center part consists of a tailstock center seat 12, a center 13, a bearing 14 and a thrust bearing 15. The workpiece jacking assembly is moved and positioned on the track frame 1 by the tail frame 2. The movable workpiece jacking assembly is suitable for workpieces with different lengths; the tail part of the tailstock center component is connected with a piston 11 of a bidirectional cylinder, a center 13 in the tailstock center component can rotate freely, the outer circle of the tailstock center component is in sliding fit with an inner hole of the tailstock 2, and the reversing valve controls the action function of tightly pushing and releasing a workpiece under the forward and backward action of the cylinder.

The rail frame component of the sample clamping mechanism consists of a rail frame 1 and a Y ' guide rail slide block 22, and the Y ' guide rail slide block 22 enables the sample clamping mechanism to transversely float on the Y ' shaft guide rail 20 which is parallel to the Y shaft and is arranged on the machine body. The axis of a main shaft of a workpiece rotating and feeding assembly on the sample clamping mechanism is collinear with the axis of a tailstock center on a workpiece jacking assembly and is parallel to a track and an X axis of a track frame, so that the axis of a clamped and positioned workpiece, namely an A axis servo shaft is parallel to the X axis.

Two ends of the workpiece 4 are jacked between two tops 17 and 13 of the rotary feeding assembly and the workpiece jacking assembly of the sample clamping mechanism through central holes; an A-axis servo motor 18 of the rotary feeding assembly drives a headstock spindle 17 to rotate through a coupling 19, and the friction force between the tip of the front end of the headstock spindle 17 and the center hole of the end part of the workpiece 4 drives the workpiece to perform indexing and rotating functions. The center in the tailstock center part can rotate freely, the outer circle of the tailstock center part is in sliding fit with the inner hole of the tailstock, the tail part of the tailstock center part of the workpiece jacking assembly is connected with the bidirectional cylinder piston 11, and the workpiece can be jacked and prevented from loosening under the action of the bidirectional cylinder piston.

The front side of a track frame part of the sample clamping mechanism on the lathe bed is also fixed with a one-way cylinder 10, the lathe bed is opposite to the one-way cylinder, and the other side of the track frame part is also provided with a limit block 32 and a first stroke proximity switch 30; the same side of the one-way cylinder 9 on the bed body is provided with a second stroke approach switch 31.

The grinding machine is characterized in that during grinding, the floating track frame component is acted by a constant thrust F 'exerted by the unidirectional cylinder piston 9 in the opposite direction of the Y direction, the force balance offsets the pressure F exerted by the grinding head 29 on the workpiece 4 in the Y direction, namely when the friction force of the Y' guide rail translation motion pair is not considered, the pressure F always kept by the grinding head 29 on the workpiece 4 in the Y direction during the machining process is the constant pressure F 'set by the unidirectional cylinder, and F is equal to-F'.

The constant thrust F' of the one-way cylinder piston 9 is used for compensating uneven grinding amount caused by processing loss and size error of the flexible grinding head. The magnitude of the set constant thrust of the unidirectional cylinder force 10 determines the magnitude of the grinding force of the flexible grinding head 29 on the processing surface of the workpiece 4 in the grinding processing process.

It is characterized in that during the low linear speed (20-40 m/min) grinding process, the grinding head 29 is driven by the X, Y two-axis servo system. The rotation axis of the grinding head 29 and the rotation axis of the tensile sample piece 4 are in a space vertical state, the processing track is close to the tensile direction of the tensile sample piece, and the surface stress layer of the annular processing lines of the tensile sample piece is removed by a tangent method.

Before the work is started, the distance from the top tip of the workpiece jacking assembly to the headstock is adjusted to be slightly less than the length of the workpiece by 5-10mm according to the length of the workpiece, and then the workpiece jacking assembly is locked and fixed on the rail frame. The reversing valve is pulled, the bidirectional cylinder piston 11 on the workpiece jacking assembly retreats, the tailstock center part is pulled backwards, the workpiece is put on, the reversing valve is pulled, the bidirectional cylinder piston 11 on the workpiece jacking assembly jacks forwards, and the center part of the workpiece jacking assembly is pushed to jack the workpiece forwards.

When the device works, the pressure of the one-way cylinder 10 is set through a precision pressure regulating valve according to the material quality of a machined workpiece, when the grinding head 29 is not contacted with a workpiece machining area, the sample clamping mechanism for clamping the workpiece 4 is pushed to a stopping position at the limiting block 32 by the one-way cylinder, and as shown in fig. 3, the first stroke proximity switch 30 is in an on state, the second stroke proximity switch 31 is in an off state, and the system program judges that the device is in a ready state.

After a machining program is started, the XY servo is controlled by the program to drive the grinding head 29 to move towards a machining initial position set by the workpiece 4 until the grinding head pushes a sample clamping mechanism for clamping the workpiece 4 to move for a certain distance in the Y-axis direction, the first stroke proximity switch 30 enters a closed state, and the second stroke proximity switch 31 is in a closed state, and then the system program judges that the workpiece enters a grinding state.

When the first stroke proximity switch 30 enters the closing state and the second stroke proximity switch enters the opening state, the system program judges that the first stroke proximity switch enters the overtravel state, and the program forcibly executes the backward moving command of the grinding head at Y.

Because a motion control system with more than 3 shafts is adopted, the processing process can be carried out by adopting an XY + A two-shaft linkage mode and an XYA three-shaft linkage mode.

The two-axis linkage mode program of XY + A operates as follows:

after entering the grinding state, the interpolation motion of the grinding head in the direction X, Y is carried out according to the contour projection of the workpiece machining area on an XY plane under the numerical control mode, and after the grinding head 29 finishes one X-direction stroke of the XY interpolation motion according to a system program, the grinding head leaves the workpiece 4 along the Y direction.

The track frame 1 is pushed to the stop position of the limit block 32 by the one-way cylinder again, the first travel proximity switch 30 is in an on state, the second travel proximity switch 30 is in an off state, and the system program judges that the track frame is in a ready state.

The system program enables the workpiece 4 driven by the servo motor 18 of the rotary feeding assembly to rotate by a set angle, the grinding head 29 is fed along the Y axis again to push the workpiece until the first stroke proximity switch 30 enters a closed state, the second stroke proximity switch 30 is in a closed state, the system program judges that the workpiece is in a grinding state, the next grinding is completed according to interpolation motion of the contour axis of the workpiece according to the system program, and the process is repeated continuously until the workpiece completes the uniform grinding process of the whole circumference.

The three-axis linkage mode program for XYA operates as follows:

after entering a grinding state, the grinding head 29 rotates and interpolation motion in the direction X, Y is carried out according to the contour projection of the processing area of the workpiece 4 on an XY plane under a numerical control mode, meanwhile, the A axis continuously drives the workpiece 4 to rotate, after the grinding head 29 finishes one X-direction stroke of XY interpolation motion according to a system program, the grinding head 29 leaves the workpiece 4 along the Y direction, and the processing track of the grinding head 29 in the processing area of the workpiece 4 is in a single-head reducing spiral line state. The processing track can be a multi-head reducing spiral line, such as an n-head spiral line, namely after the grinding head 29 finishes one X-direction stroke of XY interpolation motion according to a system program and leaves the workpiece 4 along the Y direction, the program controls the workpiece to rotate by 360/n degrees and then to feed for 1 time, after the grinding head 29 enters a grinding state along the Y direction and finishes one X-direction stroke of XY interpolation motion, the grinding head leaves the workpiece along the Y direction, and the operation is repeated for n times. The machining mode is characterized in that the circumferential indexing frequency, namely the change frequency of the machining state from the preparation state to the machining state, namely the spiral thread head number, and the machining texture is formed in the direction of the intersection line of the plane passing through the workpiece axis and the machining surface in the crossing angle. The smaller the linkage speed of the XYA triaxial is, the faster the grinding head rotating speed is, the larger the number of spiral line heads is, the smaller the crossing angle is, and the closer the processing texture is to the stretching direction of the stretching sample piece 4.

After the grinding is finished, the reversing valve is pulled, the bidirectional cylinder piston 11 of the workpiece jacking assembly retreats, the tailstock center part is pulled backwards, namely, the workpiece is loosened, and the workpiece is dismounted.

The diameter of the grinding head 29 is selected to ensure that the minimum curvature radius of the machining section curve which is always smaller than the machined workpiece 4 is multiplied by 2; the rotating speed is in the range of 500-2000RPM according to the difference of the diameter. Most preferably, the optimal grinding head diameter is in the range of 10-16mm, and the processing linear speed is controlled in the range of 20-40 m/min.

Preferably, the workpiece division number when the two axes of XY + A are linked is optimal according to the diameter of the workpiece, and the single-piece processing beat is within 15-25 minutes.

Preferably, the diameter of the bidirectional cylinder 11 is more than 30mm, so as to obtain a stable pressure of 50Kgf under a general pressure of 0.8MPa, and to meet the requirements of the tightening force of the workpiece to ensure the friction force required for rotating the workpiece.

Preferably, the unidirectional cylinder 10 has a cylinder diameter of less than 12mm, so that a piston of the unidirectional cylinder can obtain a stable thrust within 5Kgf under a precise pressure regulating valve by using compressed air of generally 0.8MPa, thereby being suitable for the grinding conditions of the flexible grinding head.

Preferably, the preliminary processing of the sample, such as precise numerical control turning, is carried out by adding 0.01-0.02 (mm) in the direction of the upper difference of the tolerance of the outer diameter size of the drawing under the condition of surface roughness Ra0.8-1.6; if the external circular grinding is adopted for processing, 0.005-0.01 (mm) is added according to the direction of the upper difference of the tolerance of the external diameter size on the drawing under the condition of surface roughness Ra0.8-0.4 so as to be suitable for the processing allowance of the equipment.

It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.