阅读说明：本技术 一种小升角螺纹多线错头磨削砂轮及错头螺纹磨削方法 (Multi-line staggered-head grinding wheel for small-lead-angle threads and staggered-head thread grinding method ) 是由 何理论 姜建国 李瑞光 侍威 张兆晶 黄玉平 田青 杨斌 于 2021-09-14 设计创作，主要内容包括：一种小升角螺纹多线错头磨削砂轮及错头螺纹磨削方法,砂轮与工件相对运动走螺旋运动的小升角螺纹错头磨削方法,磨削过程砂轮不需要摆动成与磨床Z轴呈一个角度,工件与砂轮的相对运动保持工件旋转一圈,砂轮沿磨床Z轴移动一个螺纹导程。巧妙的设计了一种针对小升角螺纹加工的多线砂轮,磨削过程砂轮磨削刃与工件螺纹错头接触,接触间距和内部空间增大,便于冷却液进入磨削摩擦界面,增强冷却和磨屑排出,提升螺纹磨削精度。所设计多线磨削砂轮与方法,可同时用于内、外螺纹的高效率加工。该磨削方法磨削小升角行星滚柱丝杠螺纹时,保持高精度螺纹廓形不苛求工件与砂轮轴线等高,同时也解决了内螺纹磨削难采用多线磨削的问题。(A small-lead-angle thread multi-line staggered-head grinding wheel and a staggered-head thread grinding method are disclosed, the small-lead-angle thread staggered-head grinding method is characterized in that a grinding wheel and a workpiece move in a spiral motion relatively, the grinding wheel does not need to swing to form an angle with a Z axis of a grinding machine in the grinding process, the workpiece and the grinding wheel move relatively to keep the workpiece rotating for one circle, and the grinding wheel moves for one thread lead along the Z axis of the grinding machine. The ingenious design is to the multi-thread emery wheel of little lead angle thread processing, and grinding process emery wheel grinding sword and the wrong first contact of work piece screw thread, contact interval and inner space increase, and the coolant liquid of being convenient for gets into grinding friction interface, and reinforcing cooling and abrasive dust discharge promote the screw thread grinding precision. The designed multi-line grinding wheel and the method can be simultaneously used for high-efficiency processing of internal threads and external threads. When the grinding method is used for grinding the threads of the planetary roller screw with the small lift angle, the high-precision thread profile is kept to be as high as the axis of a grinding wheel, and the problem that multi-line grinding is difficult to adopt for internal thread grinding is solved.)

1. A method for grinding a staggered thread is characterized by comprising the following steps:

1) mounting a grinding wheel (1) on a grinding wheel headstock of a grinding machine, wherein the axis Z of the grinding wheel (1) is parallel to the axis Z of the grinding machine; the excircle of the grinding wheel (1) is flattened by adopting a diamond pen, and the dial indicator is utilized to measure the different rotating speeds of the grinding wheel (1) around the axis z thereofDegree n₁The lower outer circle jumps until the circle jump is smaller than a threshold value;

2) clamping a workpiece (2) on a workpiece headstock of a thread grinding machine through a clamp (3), adjusting the outer circle and the end face of the workpiece (2) to jump around a C shaft, and enabling the axis of the workpiece (2) to be parallel to a Z shaft of the grinding machine;

3) moving the relative position of the grinding wheel (1) and the workpiece (2) along the axis z direction and the radial x direction of the grinding wheel (1), evaluating whether the machining motion stroke of the grinding wheel (1) meets the machining requirement, if so, entering the step 4), otherwise, repeating the steps 1) and 3) until the requirement is met;

4) utilizing a diamond disc wheel or a diamond forming roller to shape the grinding wheel (1), wherein the shape of the shape is related to the tooth form, the thread pitch and the number of heads of the thread of the workpiece (1);

5) moving the grinding wheel (1) along the X axial direction of the machine tool until the outer contour of the grinding wheel (1) is contacted with the inner hole surface of the workpiece (2); moving the grinding wheel (1) along the Z direction of the machine tool until the left end of the grinding wheel (1) is contacted with the right end face of the workpiece (2), recording X-axis and Z-axis coordinate values of the grinding wheel (1) contacted with the workpiece (2) as tool setting starting points, and taking a position which is away from the tool setting starting points in the Z-axis negative direction as a grinding starting point;

6) the grinding wheel (1) and the workpiece (2) are driven to move relatively, the workpiece (2) rotates around a C shaft at a rotating speed n, the grinding wheel (1) does linear motion with a motion speed f along a Z shaft of the grinding machine, the workpiece (2) is guaranteed to rotate for one circle, and the grinding wheel (1) moves for a thread lead along the Z shaft of the grinding machine; when the grinding wheel (1) moves to a certain processing length along the Z-axis direction of the grinding machine, the grinding wheel (1) returns to the grinding starting point;

7) after the grinding wheel (1) is fed and moved for a certain value along the X-axis direction, thread machining is continued according to the step 5) until the pitch diameter of the machined thread meets the design requirement; then loosening the fixture (3) and taking down the workpiece (2);

8) and repeating the steps 2) -7) to process the next workpiece (2).

2. A method of grinding a wrong-start thread according to claim 1 wherein: the threshold is 0.001 mm.

3. A method of grinding a wrong-start thread according to claim 1 wherein: the clamp (3) is in a clamping jaw type and is used for grinding internal thread workpieces, or a tip jacking structure is used for grinding external thread workpieces.

4. A method of grinding a wrong-start thread according to claim 1 wherein: the workpiece (2) is an internal thread workpiece or an external thread workpiece.

5. The utility model provides a little lead angle screw thread multi-line grinding emery wheel which characterized in that: the number m of the grinding edges of the grinding wheel (1) and the number n of the thread heads of the thread workpiece (5) can be the same or different, and the profiles of the m grinding edges can be the same or different.

6. The small lead thread multi-line grinding wheel according to claim 5, wherein: the axial distribution of the m grinding edges follows the following conditions:

wherein S represents a thread lead; i. j is an integer greater than zero; m is the number of grinding edges of the grinding wheel; n is the number of the thread heads of the workpiece; l is₀Indicating the distance of the first grinding edge from the end of the grinding wheel; l is_iThe distance of the ith grinding edge from the end of the grinding wheel is shown.

7. The small lead thread multi-line grinding wheel according to claim 5, wherein: the grinding wheel is characterized in that for grinding threads with lead angles of less than 3 degrees, the profile of the grinding wheel (1) is consistent with the profile of the thread profile of a workpiece (2) to be ground; for the threads with the grinding helix angle larger than 3 degrees, the profile of the grinding wheel (1) is reversely obtained according to the enveloping principle of the thread grinding process.

8. The small lead thread multi-line grinding wheel according to claim 5, wherein: when the number of the screw heads of the workpiece (2) is 1, the number m of the grinding edges of the grinding wheel (1) is adjusted according to the width of the grinding wheel and is 1 or any integer larger than 1; when the grinding edge number m of the grinding wheel (1) is more than 1, the grinding edge distance is positive integral multiple of the thread pitch of the workpiece (2), and the diameters of the grinding edges are equal in height or gradually increase.

9. The small lead angle threaded multi-line grinding wheel of claim 8, wherein: when the grinding wheel (1) grinds the number m of edges>1, the diameter D of the jth grinding edge is satisfied_jSmaller than the (j + 1) th grinding edge diameter D_j+1 wherein (D)_m-D₀) And/2 is not more than the full thread height of the thread of the workpiece (2).

10. The small lead thread multi-line grinding wheel according to claim 5, wherein: the small-diameter end of the grinding edge of the grinding wheel (1) is the first grinding end of the thread grinding.

Technical Field

The invention relates to a multi-line grinding wheel for small-lift-angle threads and a method for grinding staggered threads, belonging to the field of mechanical manufacture.

Background

The multi-line grinding wheel thread grinding is developed on the basis of single-line grinding wheel grinding, is an important synergistic process in thread machining, and although the grinding efficiency is greatly improved, in the grinding wheel grinding process, a plurality of tooth grooves of the grinding wheel participate in grinding, the grinding force is increased, the grinding heat is increased, the grinding wheel abrasion is accelerated, in order to ensure the thread machining precision, the grinding process needs to be fully cooled, and the grinding wheel needs to be frequently dressed. In order to obtain better tooth form precision, when a thread is ground by a thread grinding machine, a grinding wheel swing angle which is the same as a lead angle of the ground thread needs to be provided so as to realize that a shape modification profile of a grinding wheel is consistent with a normal profile of the thread. The grinding method has very high requirements on the shape-correcting capability of the grinding wheel, the height of the grinding wheel and the axis of a workpiece, the tool setting of the grinding wheel, the rigidity of a grinding system and a grinding cooling system, and because the multi-thread grinding is difficult to realize at the same time, the multi-thread grinding is only used for rough machining and semi-finish machining all the time.

With the development of a CNC (computerized numerical control) system, the defect of the traditional grinding machine in repairing the multi-line grinding wheel is overcome by the high-precision insertion repairing function, so that the thread grinding machine does not depend on a forming roller any more, and the thread grinding of the multi-line grinding wheel also becomes one of the choices of thread precision machining. Although the bottleneck of multi-thread grinding is not restricted by the precise dressing of the grinding wheel, the problems of grinding burn, reduction of grinding precision and unbalance of grinding force caused by that cooling liquid is difficult to enter a grinding area due to dense grinding tooth sockets in the multi-thread grinding wheel thread grinding are difficult to solve. The traditional thread grinding of the swing angle of the grinding wheel still has the problems of high rigorous requirements on the axes of the grinding wheel and a workpiece and the like when multi-thread grinding is adopted, and the problem that multi-thread grinding cannot be adopted for internal threads, and the development of multi-thread grinding is also restricted.

Disclosure of Invention

The technical problem solved by the invention is as follows: the defects of the prior art are overcome, and a small-lift-angle thread multi-line grinding wheel and a staggered head grinding method are provided; based on a grinding method that the axis of a grinding wheel and the axis of a workpiece are parallel to the Z axis of a grinding machine, the grinding wheel and the workpiece move in a spiral motion relatively, the multi-line grinding wheel with a small lift angle and a small pitch thread is designed, the thread is ground in a staggered head mode, high-efficiency multi-line grinding of the planetary roller screw is achieved, and the problem of high-efficiency machining of internal and external threads of a typical part of the planetary roller screw is solved. When the grinding method is used for grinding the threads of the planetary roller screw with the small lift angle at high precision, the contour of the high-precision threads is kept to be as high as the axis of a grinding wheel, the size of the pitch diameter of the threads is only influenced, and the problem that multi-line grinding is extremely difficult to adopt for internal thread grinding is solved.

The technical scheme of the invention is as follows: a method for grinding a staggered thread comprises the following steps:

1) mounting a grinding wheel on a grinding wheel headstock of a grinding machine, wherein the axis Z of the grinding wheel is parallel to the axis Z of the grinding machine; flattening the outer circle of the grinding wheel by using a diamond pen, and measuring the outer circle runout of the grinding wheel around the axis z of the grinding wheel at different rotating speeds n by using a dial indicator until the circle runout is smaller than a threshold value;

2) clamping a workpiece on a workpiece headstock of a thread grinding machine through a clamp, and adjusting the outer circle and the end surface of the workpiece to jump around a C shaft, wherein the axis of the workpiece is parallel to a Z shaft of the grinding machine;

3) moving the relative position of the grinding wheel and the workpiece along the z-direction and the radial x-direction of the axis of the grinding wheel, evaluating whether the machining motion stroke of the grinding wheel meets the machining requirement, if so, entering the step 4), and otherwise, repeating the steps 1) and 3) until the requirement is met;

4) utilizing a diamond disc wheel or a diamond forming roller to shape the grinding wheel, wherein the shape of the shape is related to the tooth form, the thread pitch and the number of heads of the thread of the workpiece;

5) moving the grinding wheel along the X axial direction of the machine tool until the outer contour of the grinding wheel is contacted with the inner hole surface of the workpiece; moving the grinding wheel along the Z direction of the machine tool until the end part of the left side of the grinding wheel contacts with the end surface of the right side of the workpiece, recording X-axis and Z-axis coordinate values of the contact of the grinding wheel and the workpiece as a tool setting starting point, and taking a position which is away from the tool setting starting point in the Z-axis negative direction as a grinding starting point;

6) the grinding wheel and the workpiece are driven to move relatively, the motion mode is that the workpiece rotates around a C shaft at a rotating speed n, and meanwhile, the grinding wheel does linear motion with a motion speed f along a Z shaft of the grinding machine, so that the workpiece rotates for one circle, and the grinding wheel moves for a thread lead along the Z shaft of the grinding machine; when the grinding wheel moves to a certain processing length along the Z-axis direction of the grinding machine, the grinding wheel returns to the grinding starting point;

7) after the grinding wheel is fed and moved for a certain value along the X-axis direction, thread machining is continued according to the step 5) until the pitch diameter of the machined thread meets the design requirement; then loosening the fixture and taking down the workpiece;

8) and repeating the steps 2) -7) to process the next workpiece.

The threshold is 0.001 mm.

The clamp adopts a clamping jaw type for grinding internal thread workpieces, or adopts a tip jacking structure for grinding external thread workpieces.

The workpiece is an internal thread workpiece or an external thread workpiece.

The number m of grinding edges of the grinding wheel and the number n of thread heads of a threaded workpiece can be the same or different, and the profiles of the m grinding edges can be the same or different.

The axial distribution of the m grinding edges follows the following conditions:

wherein S represents a thread lead; i. j is an integer greater than zero; m is the number of grinding edges of the grinding wheel; n is the number of the thread heads of the workpiece; l is₀Indicating the distance of the first grinding edge from the end of the grinding wheel; l is_iIndicating distance of ith grinding edge from grinding wheel endDistance.

The grinding wheel has a profile consistent with the profile of the thread profile of the workpiece to be ground for grinding the thread with a lead angle smaller than 3 degrees; for the threads with grinding helix angle larger than 3 degrees, the profile of the grinding wheel is reversely solved according to the enveloping principle of the thread grinding process.

When the number of the thread heads of the workpiece is 1, the number m of the grinding edges of the grinding wheel is adjusted according to the width of the grinding wheel and is 1 or any integer larger than 1; when the grinding wheel grinding edge number m is more than 1, the grinding edge distance is positive integral multiple of the thread pitch of the workpiece, and the diameters of the grinding edges are equal in height or gradually increase.

When the grinding wheel grinds the edge number m>1, the diameter D of the jth grinding edge is satisfied_jSmaller than the (j + 1) th grinding edge diameter D_j+1 wherein (D)_m-D₀) And/2 is not more than the full thread height of the workpiece thread.

The small-diameter end of the grinding edge of the grinding wheel is the first grinding end of the thread grinding.

Compared with the prior art, the invention has the advantages that:

1) compared with the traditional thread grinding method, the grinding method and the multi-line grinding wheel disclosed by the invention can be suitable for grinding internal threads and external threads, the universality is better, and the grinding efficiency is obviously improved;

2) the multi-line grinding wheel thread grinding method does not need the workpiece to be as high as the grinding wheel axis, and can obtain higher thread profile precision;

3) the staggered-head multi-line grinding wheel has obvious advantages in small-pitch thread grinding, the grinding contact distance is increased, cooling liquid can conveniently enter a grinding friction interface, the cooling and abrasive dust discharging effects can be enhanced, and the grinding precision is favorably improved.

4) According to the invention, the tooth height distribution height can be conveniently adjusted aiming at the staggered-head multi-line grinding wheel of the single-head thread, coarse and fine grinding can be realized through one-time dressing, and the grinding precision and efficiency are both considered.

Drawings

Figure 1 is a schematic view of a method for grinding a staggered head of an internal thread,

fig. 2 is a schematic view of the external thread staggered-head grinding multi-line grinding wheel.

FIG. 3 is a schematic view of a single-thread staggered-head grinding unequal-height multi-line grinding wheel.

Detailed Description

The specific structure of the present embodiment is described below in conjunction with several views.

Fig. 1 shows a method for grinding a wrong-end thread, which comprises a grinding wheel 1, a workpiece 2 and a clamp 3, wherein the workpiece 2 is clamped on the clamp 3 of a thread grinding machine, the axis of the workpiece 2 is parallel to the Z axis of the grinding machine, and the axis of the grinding wheel 1 is parallel to the Z axis of the grinding machine, and the method is implemented in detail as follows:

1) mounting a grinding wheel 1 on a grinding wheel headstock of a grinding machine, wherein the axis Z of the grinding wheel 1 is parallel to the axis Z of the grinding machine; the excircle of the grinding wheel 1 is flattened by adopting a diamond pen, and the dial indicator is utilized to measure the different rotating speeds n of the grinding wheel 1 around the axis z thereof₁The lower outer circle jumps until the circular jump is less than 0.001 mm;

2) clamping a workpiece 2 on a workpiece headstock of a thread grinding machine through a clamp 3, and adjusting the outer circle and the end face of the workpiece 2 to jump around a C axis and the axis of the workpiece 2 to be parallel to a Z axis of the grinding machine;

3) moving the relative position of the grinding wheel 1 and the workpiece 2 along the axis z direction and the radial x direction of the grinding wheel 1, evaluating whether the machining motion stroke of the grinding wheel 1 meets the machining requirement, if so, entering the step 4), otherwise, repeating the steps 1) and 3);

4) a grinding wheel dressing program is compiled, and a diamond disc wheel or a diamond forming roller is used for dressing the grinding wheel 1, wherein the dressing shape is related to the tooth form, the thread pitch and the number of heads of the thread of the workpiece 1;

5) moving the grinding wheel 1 along the X axial direction of the machine tool until the outer contour of the grinding wheel 1 is contacted with the inner hole surface of the workpiece 2; moving the grinding wheel 1 along the Z direction of the machine tool until the left end of the grinding wheel 1 is contacted with the right end face of the workpiece 2, and recording X-axis and Z-axis coordinate values of the grinding wheel 1 contacted with the workpiece 2 as a tool setting starting point;

6) a thread grinding program is compiled, the grinding wheel 1 and the workpiece 2 are driven to move relatively, the movement mode is that the workpiece (2) rotates around the C axis, the grinding wheel 1 makes linear motion along the Z axis of the grinding machine, the workpiece 1 is ensured to rotate for one circle, and the grinding wheel 1 moves for one thread lead along the Z axis of the grinding machine; when the grinding wheel 1 moves to a certain processing length along the Z-axis direction of the grinding machine, the grinding wheel 1 returns to the starting point of tool setting;

7) after the grinding wheel 1 is fed and moved for a certain value along the X-axis direction, thread machining is continued according to the step 5) until the pitch diameter of the machined thread meets the design requirement; then the fixture 3 is loosened, and the workpiece 2 is taken down;

8) and repeating the steps 2) -7) to process the next workpiece 2.

The clamp 3 can be in a clamping jaw type and used for grinding internal thread workpieces, and can also be in a tip supporting structure and used for grinding external thread workpieces.

The workpiece 2 may be an internal thread workpiece or an external thread workpiece.

Fig. 2 shows a grinding multi-line grinding wheel for grinding staggered heads of external threads, wherein the number m of grinding edges of the grinding wheel 1 and the number n of thread heads of a threaded workpiece 2 can be the same or different, and the profiles of m grinding edges can be the same or different; the axial distribution of the m grinding edges follows the following conditions:

wherein S represents a thread lead, i, j are integers greater than zero; m is the number of grinding edges of the grinding wheel; n is the number of the thread heads of the workpiece; l is₀Indicating the distance of the first grinding edge from the end of the grinding wheel, L_iThe distance of the ith grinding edge from the end of the grinding wheel is shown.

The axial distribution of the grinding edges of the grinding wheel in fig. 2 is related to the number of the thread ends of the workpiece 2, typically, the number of the thread ends of the workpiece 2 is 1, 2, 3, 4, 5, and then the number of the thread ends ground by 5 grinding edges of the grinding wheel 1 is 1, 3, 5, 2, 4; if the number of the thread starts of the workpiece 2 is 1, 2, 3, the number of the grinding thread starts corresponding to the three grinding edges of the grinding wheel 1 is 1, 3, 2.

The grinding wheel described in figure 2 can be used for external thread grinding and internal thread grinding, and the external diameter of the grinding wheel is related to the diameter of a workpiece and the grinding wheel specification requirement of a grinding machine.

The profile of the grinding wheel in FIG. 2 is consistent with the profile of the thread profile of the workpiece to be ground for grinding threads with lead angles less than 3 degrees; for grinding threads with a helix angle larger than 3 degrees, the profile needs to be reversely solved according to the envelope principle of the thread grinding process.

Fig. 3 shows a grinding wheel for single-start thread staggered-start grinding, that is, when the number of starts of a thread used for a threaded workpiece 1 is 1, the number m of grinding edges of the grinding wheel 1 can be adjusted according to the width of the grinding wheel, and may be 1 or an arbitrary integer larger than 1. When the grinding wheel 1 grinds the edge number m>1, the distance between the grinding edges is positive integral multiple of the thread pitch of the workpiece 2 (the multiple is 1, 2 and 3 … …), the diameters of the grinding edges are equal in height or gradually increase, and the requirement of the diameter D of the jth grinding edge is met_jSmaller than the (j + 1) th grinding edge diameter D_j+1 wherein (D)_m-D₀) And/2 is not greater than the full thread height of the thread of the workpiece 2.

The grinding edge profile with the largest diameter of the grinding wheel in fig. 3 is the final finish grinding profile, the grinding edges with the largest diameter have the same height, and can be 1 or more, and the heights and widths of the rest grinding edges are smaller than the grinding edges with the largest diameter. The number of grinding edges may be 1, 2, 3, 4, 5, etc., the number of rotations being related to the width of the grinding wheel 1 and the structural limitations of the workpiece 2.

In the grinding wheel shown in fig. 3, the small diameter end of the grinding edge of the grinding wheel is the first grinding end of the thread grinding.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make modifications and variations of the present invention without departing from the spirit and scope of the present invention.