Internal thread grinding method and equipment

Abstract

The invention discloses an internal thread grinding method and equipment, belongs to a precision machining technology, and aims to solve the problem that the precision of an existing internal thread grinding process is not high. A workpiece rotates, a thread mold and the workpiece rotate relatively, and the thread mold and the workpiece move relatively in the axial direction due to meshing of an external thread and an internal thread; therefore, while the thread mold and the workpiece are engaged in a circumferential rotation manner, the thread mold and the workpiece also move in a spiral entering or retreating manner in the axial direction, so that an external thread of the thread mold is engaged with internal threads at different positions in the axial direction of the workpiece, and a grinding agent is injected into the engaged position to achieve the purpose of grinding the whole inner surface of the internal threads.

Description

Technical Field

[0001] The invention belongs to the field of precision machining technology, and in particular relates to an internal thread grinding method and equipment. Background Art

[0002] The existing technology can only perform forming turning, milling and grinding on the internal thread, but cannot grind the inner surface of the internal thread. The surface accuracy of the internal thread grinding process is rough. With the advancement of science and technology and industrial upgrading, the requirements for thread accuracy, noise, life, etc. are getting higher and higher, so the work of improving the accuracy of internal threads is imminent. Summary of the invention

[0003] The technical problem to be solved and the technical task proposed by the present invention is to overcome the defects of low precision and rough surface of the existing internal thread grinding process, and to provide an internal thread grinding method and equipment, aiming to improve the precision of the internal thread.

[0004] To achieve the above object, the internal thread grinding method of the present invention comprises the following steps:

[0005] (1) extending the external thread of the threaded die into the threaded hole of the workpiece, wherein the outer diameter of the external thread of the threaded die is smaller than the aperture of the threaded hole;

[0006] (2) partially meshing the external thread of the threaded die with the internal thread of the workpiece in the circumferential direction;

[0007] (3) rotating the workpiece and rotating the thread die and the workpiece relative to each other, and relying on the meshing of the external thread and the internal thread, causing the thread die and the workpiece to move relative to each other axially to achieve follow-up axial feeding; during this period, adding abrasive to the meshing area;

[0008] (4) Disengage the external thread from the internal thread;

[0009] (5) Remove the external thread of the thread die from the threaded hole of the workpiece.

[0010] This method causes the workpiece to rotate and the threaded mold and the workpiece to rotate relative to each other and relies on the meshing of the external thread and the internal thread to cause the threaded mold and the workpiece to move relative to each other axially, so that the threaded mold and the workpiece can rotate and mesh in the circumferential direction while also moving in or out of the axial direction in a spiral manner, thereby achieving the meshing of the external thread of the threaded mold with the internal thread of the workpiece at different axial positions, and injecting abrasives at the meshing point to achieve the purpose of grinding the entire inner surface of the internal thread.

[0011] Preferably, in step (3), the internal thread of the workpiece and the external thread of the threaded mold maintain radial force. The radial force can keep the internal thread and the external thread at an appropriate radial meshing pressure and maintain the meshing relationship.

[0012] Preferably, in step (2), the threaded mold is subjected to an axial damping force. The axial damping force is used to keep the threaded mold in a relatively stable position in the axial direction, promote the external thread of the threaded mold to mesh with the internal thread of the workpiece as soon as possible, and avoid axial movement during initial contact and meshing with the workpiece.

[0013] Preferably, the direction of the relative rotation between the thread die and the workpiece is changed to change the direction of the follower axial feed, so as to grind the internal thread reciprocally along the axial direction, so as to achieve the purpose of repeatedly grinding the entire inner surface of the internal thread.

[0014] Preferably, a stroke is set to confine the reciprocating grinding within the stroke to avoid excessive idle strokes and improve grinding efficiency.

[0015] Preferably, at the meshing contact point between the external thread and the internal thread, the rotation direction and adjacent groove pitch of the external thread and the internal thread are consistent (if the thread is single-start, the pitch is the lead; if the thread is multi-start, the pitch is one-fifth of the "number of heads" of the lead; for example, if the thread is 5-start, the adjacent thread pitch is 1 / 5 of the lead length), and the normal cross-sectional profile of the external thread is different according to the morphology and diameter of the internal thread, so as to maximize the contact area with the groove without interfering with the profile of the internal thread, so as to improve the grinding accuracy and grinding efficiency.

[0016] Preferably, the axis of the threaded die is parallel to the axis of the threaded hole to avoid diameter errors of the internal threads of the workpiece.

[0017] Preferably, the threaded die and the workpiece rotate in the same direction and maintain a speed difference so that the threaded die grinds the workpiece. In this way, under the premise of maintaining a speed difference between the threaded die and the workpiece, a higher speed can be maintained to improve the grinding efficiency.

[0018] To achieve the above object, the internal thread grinding device of the present invention comprises:

[0019] A first actuator head provides rotation about a first axis,

[0020] A second actuator head provides rotation about a second axis,

[0021] in:

[0022] At least one of the first execution head and the second execution head provides active rotation,

[0023] One of the first execution head and the second execution head is driven by the first driving system to be axially movable, and the other is driven by the second driving system to be radially movable, so as to realize relative axial movement and relative radial movement of the first execution head and the second execution head;

[0024] Its characteristic is that one of the first execution head and the second execution head is also configured to perform follow-up axial feeding.

[0025] Accordingly, the threaded mold and the workpiece are separately arranged on the first execution head and the second execution head, so that the threaded mold and the workpiece can rotate around their respective axes (the first axis or the second axis), and the active rotation provided by at least one of the first execution head and the second execution head causes the threaded mold and the workpiece to rotate relative to each other, and then the relative axial movement and relative radial movement of the first execution head and the second execution head are used to achieve the rapid advance and retreat of the relative position of the threaded mold and the workpiece; and, during the grinding process, the threaded engagement of the threaded mold and the workpiece is used to achieve the follow-up axial feed of the first execution head or the second execution head, so that the threaded mold and the workpiece produce relative axial movement. Accordingly, the internal threads of various axial parts of the workpiece are ground by the follow-up axial feed, and the internal threads of various circumferential parts of the workpiece are ground by the rotation of the workpiece.

[0026] Preferably, the first driving system is arranged on one side of the bed, and includes a first carriage that can be driven to move axially, and a first slide rail that is arranged on the first carriage and can produce a follow-up axial feed relative to the first carriage; the second driving system is arranged on the other side of the bed, and includes a second carriage that can be driven to move radially, and a second slide rail that is arranged on the second carriage and can produce a radial micro-motion relative to the second carriage; one of the first execution head and the second execution head is arranged on the first slide rail, and the other is arranged on the second slide rail. Axial movement is achieved by the action of the first carriage, and follow-up axial feed relative to the first carriage is achieved by the action of the first slide rail, radial movement is achieved by the action of the second carriage, and radial micro-motion relative to the second carriage is achieved by the action of the second slide rail.

[0027] Preferably, a damping element for generating axial damping force is provided on the first slide rail, so as to keep the first slide rail and the threaded mold in a relatively stable position in the axial direction, promote the external thread of the threaded mold to mesh with the internal thread of the workpiece as soon as possible, and avoid axial movement during initial contact and meshing with the workpiece.

[0028] Preferably, a first travel switch and a second travel switch are arranged in the axial direction, and the first travel switch and the second travel switch limit the travel of the first slide rail in the axial feed, so as to avoid excessive idle travel of the first slide rail and improve the grinding efficiency.

[0029] Preferably, the second slide rail is provided with an engagement loading element that generates radial force when the second slide rail slightly moves radially, so as to maintain a certain radial pressure between the external thread of the threaded mold and the internal thread of the workpiece during grinding, thereby improving grinding efficiency and grinding quality, and also promoting the engagement of the external thread of the threaded mold with the internal thread of the workpiece.

[0030] Preferably, the second slide rail or the first slide rail comprises an upper plate and a lower plate stacked up and down, the upper plate is configured to be slightly rotated relative to the lower plate around a rotating shaft in the middle thereof and can be locked, and one of the first execution head and the second execution head is configured on the upper plate. Accordingly, the relative position relationship between the axis of the workpiece and the axis of the threaded mold can be adjusted as needed to ensure the grinding accuracy.

[0031] Preferably, one of the first executing head and the second executing head provides active rotation, and the other provides passive rotation, or both of the first executing head and the second executing head provide active rotation.

[0032] Preferably, the internal thread grinding equipment comprises:

[0033] A thread die having external threads;

[0034] A fixture, used to clamp the workpiece;

[0035] The threaded mold and the fixture are separately axially arranged on the first execution head and the second execution head to realize the relative axial movement and relative radial movement of the threaded mold and the workpiece.

[0036] The thread mold can be provided to the user along with the grinding equipment, or the user can configure it by himself according to the normal cross-sectional morphology, thread guide angle, pitch, etc. of the internal thread of the workpiece when using the grinding equipment. At the meshing contact between the external thread and the internal thread, the rotation direction and adjacent groove pitch of the external thread and the internal thread are consistent (if the thread is single-start, the pitch is the lead, if the thread is multi-start, the pitch is one-fifth of the "number of heads" of the lead, for example, if the thread is 5-start, the adjacent thread pitch is 1 / 5 of the lead length), and the normal cross-sectional profile of the external thread is different according to the morphology and diameter of the internal thread, and under the premise of not interfering with the internal thread profile, the contact surface with the groove is increased as much as possible to improve the grinding accuracy and grinding efficiency.

[0037] Preferably, the first axis is parallel to the second axis to ensure grinding accuracy.

[0038] The present invention causes the workpiece to rotate and the threaded mold and the workpiece to rotate relative to each other, and relies on the meshing of the external thread of the threaded mold with the internal thread of the workpiece to cause the threaded mold and the workpiece to move relative to each other axially, so that the threaded mold and the workpiece can rotate and mesh in the circumferential direction, and also have a spiral entry or retreat displacement movement in the axial direction to realize follow-up axial feeding, thereby realizing the meshing of the external thread of the threaded mold with any part of the internal thread of the workpiece, so as to achieve the purpose of all-round grinding of the entire inner surface of the internal thread of the workpiece.

[0039] The present invention enables the formed outer surface of the external thread of the threaded die to perfectly mesh with the formed inner surface of the internal thread of the workpiece and to rotate differentially around their respective axes, especially to rotate differentially in the same direction, thereby achieving efficient grinding.

[0040] The rotation speed of the threaded mold and the rotation speed of the workpiece can be driven and controlled by separate systems respectively, or one can be rotated by the other, so that at least one of the two is movable in the axial direction. The first travel switch and the second travel switch are arranged on both sides of the movable part to monitor the axial limit position of the axial movable part. When the movable part moves to the limit position, the corresponding travel switch is triggered and moves in the opposite direction, so that the threaded mold and the workpiece can move back and forth relative to each other in the axial direction to realize repeated grinding.

[0041] The present invention delivers abrasives into the meshing area during grinding to improve the grinding effect.

[0042] The invention can be used to grind internal threads with normal cross-sectional profiles of various shapes and has a wide application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is an isometric view of the internal thread grinding device of the present invention;

[0044] Figure 2 It is a schematic diagram of the threaded mold of the present invention;

[0045] Figure 3 is a schematic diagram of a first execution head of the present invention;

[0046] Figure 4 is a schematic diagram of an upper plate and a lower plate of a second skateboard of the present invention;

[0047] Figure 5 It is a schematic diagram of an internal thread with a triangular groove in normal cross-section;

[0048] Figure 6 It is a schematic diagram of an internal thread with a trapezoidal groove in normal cross-section;

[0049] Figure 7 It is a schematic diagram of an internal thread with a sawtooth groove in the normal cross-section;

[0050] Figure 8 It is a schematic diagram of an internal thread with a rectangular groove in normal cross-section;

[0051] Fig. 9 It is a schematic diagram of an internal thread with a circular groove in normal cross-section;

[0052] Fig.10 It is a schematic diagram of an internal thread with a peach-shaped groove in normal cross-section;

[0053] Fig.11 It is a schematic diagram of an internal thread with a π-shaped groove in normal cross-section;

[0054] Fig.12 It is a schematic diagram of the thread die extending into the threaded hole of the workpiece;

[0055] Fig.13 for Fig.12 AA section view;

[0056] Fig.14 It is a schematic diagram of the internal thread of the thread die contacting the internal thread of the workpiece;

[0057] Fig.15 for Fig.14 BB section view;

[0058] Fig.16 It is a schematic diagram of partial meshing of the internal thread of the thread die and the internal thread of the workpiece in the circumferential direction;

[0059] Fig.17 for Fig.16 CC section view of ;

[0060] Description of the numbers in the figure:

[0061] 1 threaded mold, 101 threaded mold axis, d outer diameter of external thread, 2 first execution head, 201 axis, 3 first slide rail, 4 first carriage, 5 bed, 6 first driving device, 7 first stroke switch, 8 second stroke switch, 9 second driving device, 10 second carriage, 11 second slide rail, 1101 upper plate, 1102 lower plate, 12 second execution head, 13 fixture, 14 workpiece, 1401 axis, D aperture of threaded hole, 15 rotating shaft, 16 damping element, 17 engaging loading element. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention are intended to cover non-exclusive inclusions. For example, a method or product comprising a series of technical features is not necessarily limited to those technical features clearly listed, but may also include other technical features that are not clearly listed and can be included in the method or product.

[0064] In the description of the present invention, it should be understood that the terms "up", "down", "left", "right", "radial", "axial" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Among them, "up" and "down", "left" and "right", "front" and "back" are opposite directions, and "radial" and "axial" are perpendicular. In the illustrated structure, the axial direction is consistent with the left-right direction; the radial direction is perpendicular to the axial direction, and the front-to-back direction is a special case of the radial direction.

[0065] In the description of the present invention, it is necessary to understand that the technical features defined by the terms "first", "second" and the like with sequential concepts are only for the purpose of clearly describing the defined technical features so that the defined technical features can be clearly distinguished from other technical features, but do not represent such naming in actual implementation, and therefore cannot be understood as a limitation of the present invention.

[0066] The present invention is described in detail below in conjunction with specific embodiments and accompanying drawings.

[0067] Figure 1 The internal thread grinding equipment shown includes:

[0068] like Figure 3 The first execution head 2 shown is configured to be driven by a first driving system to move axially;

[0069] like Figure 2 The threaded die 1 shown has an external thread, which is directly or indirectly mounted on the first execution head 2 and extends axially toward the workpiece side;

[0070] The second execution head 12 is configured to be driven by a second driving system to move radially, and a clamp 13 is arranged on the second execution head 12, and the clamp 13 is used to clamp the workpiece 14 and keep the axis 1401 of the workpiece extending axially and drive the workpiece to rotate;

[0071] The external thread of the threaded die 1 is used to partially mesh with the internal thread of the workpiece in the circumferential direction, and the internal thread is ground in all directions by the rotation of the workpiece, the relative rotation of the threaded die and the workpiece, and the axial relative movement of the threaded die and the workpiece caused by the relative rotation;

[0072] The first execution head 2 is also configured to follow the axial relative movement and axial feeding.

[0073] Specifically, the first driving system includes a first carriage 4 that can be driven to move axially, a first slide rail 3 that is arranged on the first carriage 4 and can generate a follow-up axial feed relative to the first carriage, the first carriage 4 is arranged on one side of the bed 5 and is pulled by the first driving device 6 to move left and right, the first slide rail 3 is arranged on the first carriage 4 to move axially, and the first execution head 2 is directly or indirectly arranged on the first slide rail 3. Accordingly, the first carriage 4 can move left and right with the first slide rail 3, the first execution head 2 and the thread mold 1. In addition, the first slide rail 3, the first execution head 2 and the thread mold 1 can also move left and right relative to the first carriage 4. This movement is called follow-up axial feed, which is achieved by the meshing rotation of the external thread of the thread mold and the internal thread of the workpiece during grinding.

[0074] The first execution head 2 can be an electric spindle, a synchronous axis, etc.

[0075] The first slide rail 3 is provided with a damping element 16 for generating an axial damping force. When the external thread of the threaded mold and the internal thread of the workpiece are in radial contact and meshing, the first slide rail 3 will be impacted by external forces (especially axial forces) and will move axially. At this time, the damping element 16 generates axial damping to resist such axial movement, thereby maintaining the stability of the first slide rail 3 and the threaded mold, avoiding axial movement when the threaded mold and the workpiece are initially contacted and meshed, and promoting the external thread of the threaded mold and the internal thread of the workpiece to align with the upper texture and mesh as soon as possible. The first travel switch 7 and the second travel switch 8 are arranged in the axial direction, and the first travel switch and the second travel switch limit the follow-up axial feed stroke of the first slide rail 3. Figure 1 As shown in FIG, the damping element 16 is preferably a spring.

[0076] Specifically, the second driving system includes a second carriage 10 that can be driven to move radially, a second slide rail 11 that is arranged on the second carriage and can produce radial micro-motion relative to the second carriage, the second carriage 10 is arranged at the other end of the bed 5 and is pulled forward and backward by the second driving device 9, the second slide rail 11 is placed on the second carriage to move forward and backward, the second execution head 12 is directly or indirectly arranged on the second slide rail 11, and the right end of the second execution head 12 is installed with a fixture 13 for clamping the workpiece 14. One end of the second execution head 12 on which the fixture 13 is installed and one end of the first execution head 2 on which the thread mold 1 is installed are arranged face to face. Therefore, the second carriage 10 can move forward and backward with the second slide rail 11, the second execution head 12, the fixture 13 and the workpiece 14. In addition, the second slide rail 11, the second execution head 12, the fixture 13 and the workpiece 14 can also move forward and backward relative to the second carriage 10 to achieve radial micro-motion, and the radial micro-motion is generated during the meshing process of the workpiece and the thread mold. When the second carriage 10 moves forward and backward with the second slide rail 11 , the second execution head 12 , the fixture 13 and the workpiece 14 , the axis 1401 of the threaded hole of the workpiece 14 is parallel to the axis 101 of the threaded die.

[0077] The second execution head 12 can be selected to have a main shaft box with a tail directly connected to the motor, or other transmission methods can be used.

[0078] The fixture 13 can be selected from a three-jaw chuck, a four-jaw chuck, a pneumatic chuck, a film clamp, a damper clamp or a three-roller clamp according to the shape of the workpiece 14.

[0079] The second slide rail 11 is provided with an engaging loading element 17 that generates a radial force. Figure 1 As shown, the engagement loading element 17 is a spring. When the second slide rail 11, the second execution head 12, the fixture 13 and the workpiece move forward and backward relative to the second carriage 10, they are resisted by the engagement loading element 17 to generate radial force when the external thread of the thread mold is engaged with the internal thread of the workpiece. This radial force is reflected in both the grinding process and the process of the external thread of the thread mold and the internal thread of the workpiece being engaged with each other.

[0080] like Figure 4 As shown, the second slide rail 11 includes an upper plate 1101 and a lower plate 1102 stacked up and down, the upper plate 1101 is configured to be slightly rotated relative to the lower plate 1102 around the middle rotation axis 15 and can be locked, and the second execution head 12 is arranged on the upper plate 1101. Accordingly, the upper plate 1101 can be slightly rotated relative to the lower plate 1102 around the middle rotation axis 15 as needed to adjust the positional relationship between the workpiece and the threaded mold to ensure that the axis 1401 of the threaded hole of the workpiece 14 is parallel to the axis 101 of the threaded mold. In other embodiments, the upper plate 1101 and the lower plate 1102 of the second slide rail 11 can be transposed and applied to the first slide rail as needed.

[0081] Specifically, at the meshing contact point between the external thread and the internal thread, the rotation direction and adjacent groove pitch of the external thread and the internal thread are consistent (if the thread is single-start, the pitch is the lead, if the thread is multi-start, the pitch is one-fifth of the "number of heads" of the lead, for example, if the thread is 5-start, the adjacent thread pitch is 1 / 5 of the lead length), and the normal cross-sectional profile of the external thread is different according to the morphology and diameter of the internal thread, and under the premise of not interfering with the internal thread profile, the contact surface with the groove is increased as much as possible to improve the grinding accuracy and grinding efficiency. .

[0082] The clamping of the workpiece 14 by the fixture 13, the rotation of the workpiece by the fixture, the rotation of the threaded mold 1 by the first execution head 2, and the actions, sequential logical relationships, and combined linkage of the first drive device 6 and the second drive device 9 can be operated individually or automatically controlled by an electrical program.

[0083] According to the above-mentioned equipment, the grinding of the workpiece can be achieved by controlling the relative position and movement of the workpiece and the threaded mold, and the relative position and movement of the workpiece and the threaded mold include the axial and radial position relationship and rotation relationship between the two.

[0084] Specifically, the internal thread can be ground according to the following method:

[0085] The workpiece 14 is placed in the fixture 13 of the second execution head and clamped.

[0086] The first carriage 4, under the action of the first driving device 6, moves the threaded mold 1 mounted on the first execution head 2 to the left. Figure 12-13 As shown, the external thread of the threaded mold 1 is inserted into the threaded hole of the workpiece 14 to be processed; the threaded mold 1 is rotated under the drive of the first execution head. The outer diameter d of the external thread of the threaded mold 1 is smaller than the hole diameter D of the threaded hole of the workpiece 14.

[0087] The second carriage 10 moves forward under the action of the second driving device 9, and moves the workpiece 14 mounted in the fixture 13 toward the external thread of the threaded mold 1 until the workpiece 14 is moved forward. Figure 14-15 As shown, the internal thread of the workpiece 14 being processed just contacts the external thread of the thread die 1. Since the workpiece has no rotation speed at this time, the external thread of the thread die 1 and the internal thread of the workpiece 14 will slip momentarily.

[0088] At this point, since the first slide rail 3 does not move left and right relative to the first carriage 4, the second slide rail 11 does not move forward and backward relative to the second carriage 10, the damping element 16 does not deform and generate damping force, and the meshing loading element 17 does not deform and generate radial force. No radial micro-motion and follow-up axial feed are generated.

[0089] The second carriage 10 continues to feed with the workpiece 14. Due to the obstruction of the threaded mold 1, the workpiece 14, the fixture 13, the second execution head 12 and the second slide rail 11 will temporarily stop radial movement, that is, produce radial movement backward relative to the second carriage 10. This radial movement is radial micro-motion. The engagement loading element 17 is deformed due to the movement of the second slide rail 11 relative to the second carriage 10, and the stored elastic force generates radial force. As shown in the figure, the engagement loading element 17 is preferably a spring. When the first execution head 2 continues to rotate with the threaded mold, the outer thread of the threaded mold 1 and the inner thread of the workpiece 14 are aligned with the upper texture, and the obstruction is eliminated. Under the radial force generated by the engagement loading element 17, the second slide rail 11 is pushed to continue to feed forward with the workpiece 14, and gradually enter the initial stage of engagement. The second carriage 10 continues to move forward under the action of the second driving device 9, so that the inner thread of the workpiece and the outer thread of the threaded mold are partially fully engaged in the circumferential direction. Figure 16-17The figure shows the situation that the internal thread of the thread die and the external thread of the workpiece are partially and completely meshed in the circumferential direction, that is, the thread teeth of the internal thread and the external thread are completely located in the thread groove of each other.

[0090] The second carriage 10 continues to move forward under the action of the second driving device 9, while the workpiece 14, the fixture 13, the second execution head 12 and the second slide rail 11 are again hindered from moving radially forward because the internal thread of the threaded mold and the external thread of the workpiece are partially and completely engaged in the circumferential direction. The radial force generated by the engagement loading element 17 increases until it reaches the expected radial force value, and then the second driving device 9 stops working, and the second carriage 10 also stops moving radially, and the rotary grinding stage can be entered.

[0091] Then, the fixture 13 rotates the workpiece 14, and the workpiece 14 rotates in the same direction as the threaded mold 1 (eg Fig.16 The rotation speeds of the internal threads of the workpiece and the external threads of the threaded mold are different. If the difference in the linear speeds of the workpiece and the threaded mold at the meshing contact part is not greater than 20%, the workpiece and the threaded mold will produce relative rotation, relying on the meshing of the external threads of the threaded mold 1 with the internal threads of the workpiece. The workpiece and the threaded mold are like a nut and a screw drive (although only partially meshed), causing the threaded mold and the workpiece to move axially relative to each other. This axial relative movement is the follow-up axial feed, which is reflected here as the left and right movement of the threaded mold, that is, the threaded mold moves axially to mesh with different axial parts of the internal threads of the workpiece. The follow-up axial feed is achieved as the internal threads of the workpiece and the external threads of the threaded mold maintain meshing and relative rotation, and is not achieved by direct power drive.

[0092] During this period, abrasives are added to the meshing area to ensure the grinding effect. Therefore, the abrasives can be added earlier during the specific work. Moreover, it is better to transport the abrasives to the meshing area in the form of fluid, such as spraying the liquid containing abrasives to the meshing area through a pipe by a separate system.

[0093] The threaded mold 1 moves to the left until the first slide rail 3 touches the first travel switch 7, and then the control system controls the fixture 13 and the first drive head 2 to rotate in the opposite direction at the same time. The external thread of the threaded mold and the internal thread of the workpiece are also meshed, so that the threaded mold and the workpiece move in the opposite direction relative to each other, and the threaded mold 1 moves to the right to achieve follow-up axial feeding, until the first slide rail 3 touches the second travel switch 8, and then the control system controls the fixture and the first drive head to rotate in the opposite direction at the same time. This is repeated to complete the required grinding process and achieve precision grinding of the internal thread. Among them, the first travel switch and the second travel switch limit the follow-up axial feed stroke of the first slide rail.

[0094] When the grinding is finished, the second carriage 10 is quickly retracted to the initial position under the action of the second driving device 9, and the external thread of the thread mold is disengaged from the internal thread of the workpiece. At the same time, the rotation of the workpiece and the thread mold is stopped.

[0095] The first carriage 4 is retracted to the initial position under the action of the first driving device 6 , and the external thread of the threaded mold 1 is retracted from the threaded hole of the workpiece 14 .

[0096] Release the clamp 13, unload the material and replace the new workpiece to be processed.

[0097] The whole processing process is completed.

[0098] In the above embodiment, the workpiece 14 and the threaded grinding tool 1 rotate simultaneously and maintain a rotation speed difference, and the internal thread of the workpiece is fully ground in the length direction and the circumferential direction.

[0099] As described above, the illustrated grinding device grinds the workpiece by controlling the relative position and movement of the workpiece and the threaded mold through the first drive system and the second drive system. The relative position and movement of the workpiece and the threaded mold include the axial and radial position relationship and rotation relationship between the two. The relative position and movement of the workpiece and the threaded mold are also reflected in the position and movement of the first execution head and the second execution head. Based on this inspiration, the grinding process can be realized if the movement of the grinding device meets the following requirements:

[0100] The first execution head 2 provides rotation around the first axis, and the second execution head 12 provides rotation around the second axis; that is, the threaded mold and the workpiece are separately configured on the first execution head 2 and the second execution head 12; therefore, in terms of the illustrated structure, the threaded mold and the workpiece can be interchanged;

[0101] At least one of the first execution head 2 and the second execution head 12 provides active rotation, that is, one of the first execution head 2 and the second execution head 12 provides active rotation and the other provides passive rotation, or both of the first execution head 2 and the second execution head 12 provide active rotation;

[0102] One of the first execution head 2 and the second execution head 12 is driven by the first driving system to be axially movable, and the other is driven by the second driving system to be radially movable, so as to realize the relative axial movement and relative radial movement of the first execution head 2 and the second execution head 12; therefore, in terms of the illustrated structure, the first execution head 2 and the second execution head 12 can be interchanged to change their working mode;

[0103] One of the first execution head 2 and the second execution head 12 is also configured for follow-up axial feeding. Therefore, in terms of the illustrated structure, the first execution head 2 can be kept axially stationary and the second execution head 12 can be moved axially to achieve follow-up axial feeding. That is, in other embodiments, the follow-up axial feeding can also be reflected as the left and right movement of the workpiece, such as configuring the second execution head to move left and right through a slide rail or a carriage mechanism to achieve follow-up axial feeding.

[0104] In other embodiments, when the rotation of the workpiece 14 is passive, that is, the workpiece 14 is rotated by the threaded die 1 instead of being driven by an independent power during the grinding process, appropriate damping is applied to the rotation of the workpiece to ensure that the speed difference of the threaded meshing part is maintained when the workpiece and the threaded grinder rotate simultaneously, that is, the workpiece rotates differentially relative to the threaded die.

[0105] In other embodiments, the fixture may be caused to rotate with the workpiece in advance.

[0106] This equipment, equipped with a robot for loading and unloading, can achieve fully automated operation.

[0107] The first driving device and the second driving device may both be implemented by a combination of “lead screw + servo”.

[0108] The device and method are suitable for Figure 5-11 The normal cross-sectional morphology shown is the internal thread of triangular groove, trapezoidal groove, sawtooth, rectangular groove, circular groove, peach-shaped groove, and π-shaped groove. It is also suitable for internal threads with other normal cross-sectional morphologies, and is particularly suitable for the grinding of the internal thread of the reverse roller screw nut.

Claims

1. Internal thread grinding method, characterized by The following steps are involved: (1) extending the external thread of a threaded die (1) into a threaded hole of a workpiece (14), wherein the outer diameter (d) of the external thread of the threaded die is smaller than the hole diameter (D) of the threaded hole; (2) partially meshing the external thread of the threaded die with the internal thread of the workpiece in the circumferential direction; (3) rotating the workpiece (14) and the thread die (1) and the workpiece relative to each other, and relying on the meshing of the external thread and the internal thread, causing the thread die and the workpiece to move relative to each other axially to achieve follow-up axial feeding; during this period, adding abrasive to the meshing area; (4) Disengage the external thread from the internal thread; (5) Remove the external thread of the thread die from the threaded hole of the workpiece.

2. The internal thread grinding method according to claim 1, characterized in that: In step (3), the internal thread of the workpiece and the external thread of the threaded die maintain radial force.

3. The internal thread grinding method according to claim 1 or 2, characterized in that: The direction of relative rotation between the thread die and the workpiece is changed to change the direction of the follower axial feed so as to reciprocately grind the internal thread along the axial direction.

4. The internal thread grinding method according to claim 3, characterized in that: The stroke is set so that the reciprocating grinding is confined within the stroke.

5. The internal thread grinding method according to claim 1 or 2, characterized in that: The axis of the threading die is parallel to the axis of the threaded hole.

6. The internal thread grinding method according to claim 1 or 2, characterized in that: The thread die and the workpiece rotate in the same direction and maintain a speed difference so that the thread die grinds the workpiece.

7. Internal thread grinding equipment, including: The first execution head (2) provides rotation about a first axis, The second execution head (12) provides rotation about a second axis, in: At least one of the first execution head (2) and the second execution head (12) provides active rotation, One of the first execution head (2) and the second execution head (12) is driven by a first driving system to be axially movable, and the other is driven by a second driving system to be radially movable, so as to achieve relative axial movement and relative radial movement of the first execution head (2) and the second execution head (12); The characteristic is that one of the first execution head (2) and the second execution head (12) is also configured to perform follower axial feeding.

8. The internal thread grinding equipment according to claim 7, characterized in that: The first driving system is arranged on one side of the bed (5), and comprises a first carriage (4) which can be driven to move axially, and a first slide rail (3) which is arranged on the first carriage and can generate follow-up axial feeding relative to the first carriage; The second driving system is arranged on the other side of the bed (5), and comprises a second carriage (10) which can be driven to move radially, and a second slide rail (11) which is arranged on the second carriage and can produce radial micro-movement relative to the second carriage; One of the first execution head (2) and the second execution head (12) is arranged on the first slide rail (3), and the other is arranged on the second slide rail (11).

9. The internal thread grinding device according to claim 8, characterized in that: A damping element (16) for generating an axial damping force acts on the first slide rail (3).

10. The internal thread grinding equipment according to claim 8, characterized in that: A first travel switch (7) and a second travel switch (8) are arranged in the axial direction, and the first travel switch and the second travel switch limit the travel of the first slide rail's follow-up axial feeding.

11. The internal thread grinding device according to any one of claims 8 to 10, characterized in that: The second slide rail (11) is provided with an engaging loading element (17) which generates a radial force when the second slide rail (11) slightly moves radially.

12. The internal thread grinding device according to any one of claims 8 to 10, characterized in that: The second slide rail (11) or the first slide rail (3) comprises an upper plate and a lower plate stacked up and down, the upper plate being configured to be able to slightly rotate relative to the lower plate around a rotating shaft (15) in the middle thereof and to be lockable, and one of the first execution head (2) and the second execution head (12) being configured on the upper plate.

13. The internal thread grinding device according to any one of claims 7 to 10, characterized in that: One of the first executing head (2) and the second executing head (12) provides active rotation, and the other provides passive rotation, or both the first executing head (2) and the second executing head (12) provide active rotation.

14. The internal thread grinding device according to any one of claims 7 to 10, characterized in that include: A thread die (1) having an external thread; A clamp (13) for clamping a workpiece; The threaded mold (1) and the clamp (13) are separately axially arranged on the first execution head (2) and the second execution head (12) to realize relative axial movement and relative radial movement between the threaded mold (1) and the workpiece.

15. The internal thread grinding device according to any one of claims 7 to 10, characterized in that: The first axis is parallel to the second axis.

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