Internal thread grinder

Abstract

The present application provides a kind of internal thread grinder, for grinding the internal thread of shaft parts, internal thread grinder includes bed, workbench, part supporting mechanism, at least two grinding mechanisms and controller, controller is used to control part supporting mechanism drive shaft parts rotation around its center line, and control the relative movement between a pair of opposite grinding rods and shaft parts to perform internal thread grinding action, the internal thread grinding action is: a pair of opposite grinding rods from the both ends of shaft parts into the central hole to grind internal thread synchronously, the grinding wheel of the pair of opposite grinding rods is at least respectively from the grinding starting point to the grinding end point along the direction of the center line to complete the grinding internal thread process.According to the present application, while the shaft parts are driven to rotate by the part supporting mechanism, a pair of grinding rods synchronously grind the internal thread of the shaft parts, which greatly improves the efficiency of internal thread grinding.

Description

Technical Field

[0001] This invention relates to the field of metal cutting machine tool technology, and more particularly to an internal thread grinding machine. Background Technology

[0002] In metal cutting machine tools, internal thread grinding machines are used to grind the internal threads of shaft parts. Existing internal thread grinding machines typically use a chuck to clamp one end of the shaft part, allowing the grinding wheel to extend into the center hole of the shaft part from the other end to complete the internal thread grinding. However, this grinding method uses a single grinding wheel to complete the entire internal thread grinding, resulting in low grinding efficiency. Furthermore, when applied to internal thread grinding of shaft parts with a large length-to-diameter ratio, the grinding wheel needs to be manufactured to be at least longer than the shaft part. An excessively long grinding wheel is prone to deformation due to the large grinding load arm, affecting the grinding accuracy of internal threads on shaft parts with a large length-to-diameter ratio. Summary of the Invention

[0003] This invention provides an internal thread grinding machine.

[0004] Specifically, the present invention is achieved through the following technical solution:

[0005] This invention provides an internal thread grinding machine for grinding internal threads on shaft-type parts. The shaft-type parts have a through-hole, and the internal thread is disposed on the inner surface of the hole around its centerline. The internal thread grinding machine includes a bed, a worktable, a part support mechanism, at least two grinding mechanisms, and a controller. The worktable and the at least two grinding mechanisms are all mounted on the bed, and the grinding mechanisms are respectively arranged on both sides of the worktable. The part support mechanism is mounted on the worktable. The shaft-type part is rotatably supported by the part support mechanism around its centerline and is in a state where both ends are exposed. Each grinding mechanism is provided with an extension towards the part support mechanism. The grinding rods are arranged on both sides of the worktable, so that a pair of opposing grinding rods can extend from both ends of the shaft part into the center hole to grind the internal thread. The controller is used to control the part support mechanism to drive the shaft part to rotate around its center line, and to control the relative movement between the pair of opposing grinding rods and the shaft part to perform the internal thread grinding action. The internal thread grinding action is as follows: the pair of opposing grinding rods extend from both ends of the shaft part into the center hole to grind the internal thread synchronously. The grinding wheels of the pair of opposing grinding rods move at least along the center line from their respective grinding start point to grinding end point to complete the grinding internal thread process.

[0006] In some embodiments, the grinding wheels of the pair of opposing grinding rods move at least along the centerline direction from their respective grinding starting points that are close to each other to their grinding ending points that are far apart from each other to complete the grinding internal thread process.

[0007] In some embodiments, the grinding start point is located in the middle region of the central hole of the shaft part, and the grinding end point is located at both ends of the central hole of the shaft part.

[0008] In some embodiments, the grinding wheels of the pair of opposing grinding rods move at least along the centerline direction from their respective grinding starting points that are far apart to their respective grinding ending points that are close to each other to complete the grinding of internal threads.

[0009] In some embodiments, the grinding endpoint is located in the middle region of the central hole of the shaft part, and the grinding start point is located at both ends of the central hole of the shaft part.

[0010] In some embodiments, the pair of opposing grinding rods have grinding wheels with the same grit size; or, the pair of opposing grinding rods have grinding wheels with different grit sizes.

[0011] In some embodiments, when the pair of opposing grinding rods have grinding wheels with different grit sizes, the grinding wheels of the pair of opposing grinding rods move in the same direction at least along the center line, so that the internal thread is ground sequentially by the coarser and finer grit of the grinding wheels of the pair of opposing grinding rods.

[0012] In some embodiments, the part support mechanism is rotatably mounted on the worktable about a vertically extending shaft, allowing the two ends of the shaft-like part to rotate in a horizontal plane, thereby switching between the pair of opposing grinding rod positions.

[0013] In some embodiments, the part support mechanism and / or grinding mechanism are provided with an angle adjustment structure, thereby forming an angle between the grinding rod and the centerline of the shaft part to adapt the grinding rod to the thread profile angle of the internal thread.

[0014] In some embodiments, during the synchronous grinding of internal threads, either of the pair of opposing grinding rods moves continuously, reciprocatingly, or intermittently between the grinding start point and the grinding end point.

[0015] According to an embodiment of the present invention, the shaft part is made to have both ends exposed. The grinding rods of a pair of grinding mechanisms arranged on both sides of the worktable are controlled by the controller to be opposite each other and extend into the central hole. While the shaft part is driven to rotate by the part support mechanism, the pair of grinding rods simultaneously grind the internal thread of the shaft part, which greatly improves the efficiency of internal thread grinding.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] Figure 1This is a schematic diagram of an internal thread grinding machine according to an embodiment of the present invention;

[0019] Figure 2 This is a top view of an internal thread grinding machine according to an embodiment of the present invention;

[0020] Figure 3 This is a front view of an internal thread grinding machine according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the internal thread grinding state of a shaft-type part according to an embodiment of the present invention.

[0022] Figure 5a This is a schematic diagram of the grinding starting point of the first grinding method for the internal thread of a shaft part in one embodiment of the present invention.

[0023] Figure 5b This is a schematic diagram of the grinding endpoint of the first grinding method for the internal thread of a shaft part in one embodiment of the present invention.

[0024] Figure 6a This is a schematic diagram of the grinding starting point of the second grinding method for the internal thread of a shaft part in one embodiment of the present invention.

[0025] Figure 6b This is a schematic diagram of the grinding endpoint of the second grinding method for the internal thread of a shaft-type part according to an embodiment of the present invention.

[0026] Figure 7a This is a schematic diagram of the grinding starting point of the third grinding method for the internal thread of a shaft part in one embodiment of the present invention.

[0027] Figure 7b This is a schematic diagram of the grinding endpoint of the third grinding method for the internal thread of a shaft part in one embodiment of the present invention.

[0028] Figure label:

[0029] 01: Shaft parts; 10: Bed; 20: Worktable; 30: Part support mechanism; 40: Grinding mechanism; 41: Spindle; 42: Grinding rod; 43: Grinding wheel. Detailed Implementation

[0030] The invention will now be described with reference to several embodiments. It should be understood that these embodiments are described only to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0031] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to"; the terms "embodiment" and "one embodiment" are to be interpreted as "at least one embodiment"; the term "another embodiment" is to be interpreted as "at least one other embodiment"; the terms "first," "second," etc., may refer to different or the same objects; the term "setup" is not limited to direct or indirect connections, nor to specific connection methods. Other explicit and implicit definitions may also be included below.

[0032] Specific numerical values ​​or ranges may be referred to in the following description. It should be understood that these values ​​and ranges are merely exemplary and may be helpful in putting the ideas of the invention into practice. However, the description of these examples is not intended to limit the scope of the invention in any way. These values ​​or ranges may be set differently depending on the specific application scenario and requirements.

[0033] The shaft-like parts mentioned in the embodiments of this invention can be circular or non-circular shafts with uniform cross-sections, stepped shafts with variable cross-sections, or tapered shafts with variable cross-sections. Each shaft-like part has a centerline o1, extending its length along the centerline o1. A central hole is formed within the shaft-like part, and the cross-section of the central hole is centrally symmetrical with respect to the centerline o1. The central hole penetrates between the two ends of the shaft-like part, and an internal thread is provided on the inner wall surface of the central hole. The internal thread can extend continuously between the two ends of the shaft-like part, extend intermittently between the two ends of the shaft-like part, or be provided only in a localized area of ​​the central hole of the shaft-like part o1. The internal thread grinding machine of the embodiments of this invention is used to grind these internal threads.

[0034] The directional terms "horizontal," "lateral," "vertical," and "longitudinal" involved in this invention are relative definitions relative to the extension direction of the centerline o1 of the shaft part, rather than absolute positioning directions. That is to say, when the shaft part is rotated and supported by the part support mechanism, the centerline o1 of the shaft part can be parallel to the horizontal ground (horizontal grinding machine), perpendicular to the horizontal ground (vertical grinding machine), or inclined at an angle to the horizontal ground. However, "lateral," "vertical," and "longitudinal" are mutually orthogonal. The centerline o1 is parallel to the "horizontal" direction, the centerline o1 is consistent with the "lateral" direction, the centerline o1 is orthogonal to the "longitudinal" direction and is parallel to the "horizontal" direction, and the centerline o1 is orthogonal to the "vertical" direction.

[0035] As mentioned above, existing internal thread grinding methods are inefficient and unsuitable for grinding internal threads on shaft parts with large length-to-diameter ratios. The internal thread grinding machine proposed in the embodiments of the present invention at least partially solves the above-mentioned problems. Reference will be made below. Figure 1 to- Figure 7bThe structure and working principle of an internal thread grinding machine according to a horizontal exemplary embodiment of the present invention will be described. As mentioned above, the structure and working principle of the embodiments of the present invention are also applicable to vertical working methods. Figures 1-3 As shown, the internal thread grinding machine of this embodiment generally includes a bed 10, a worktable 20, a part support mechanism 30, a grinding mechanism 40, and a controller. The worktable 20 and the grinding mechanism 40 are both mounted on the bed 10. The part support mechanism 30 is mounted on the worktable 20 and is used to provide rotational support for the shaft-like part 01, allowing the shaft-like part 01 to rotate around the center line o1. The grinding mechanism 40 is arranged on both sides of the worktable 20, so that when grinding the internal thread of the shaft-like part 01, the grinding rod 42 of the grinding mechanism 40 can simultaneously extend into the center hole from both sides. The controller is electrically connected to the part support mechanism 30 and the spindle 41 of the grinding mechanism, and is used to control the part support mechanism 30 to drive the shaft-like part to rotate and feed, and to control the spindle 41 to drive the grinding rod 42 and grinding wheel 43 to rotate and feed.

[0036] In one embodiment, the part support mechanism 30 can be a gripper structure, such as a chuck-like component, which clamps the shaft part 01 in the middle region and drives it to rotate around the center line o1, thereby exposing both ends of the shaft part 01. The ends of the shaft part 01 can retract and be hidden within the part support mechanism 30, or they can extend out of the part support mechanism 30, as long as the grinding rod 42 of the grinding mechanism 40 can extend into the center hole of the shaft part 01 from the exposed ends. In another embodiment, the part support mechanism 30 can also be a roller structure, which supports the shaft part 01 and drives it to rotate around the center line o1, thereby exposing both ends of the shaft part 01. In one embodiment, such as... Figures 1-3 As shown, the number of grinding mechanisms 40 can be two, with the two grinding mechanisms 40 respectively arranged on both sides of the worktable 20. Each grinding mechanism 40 is used to align one end of the shaft part 01 and extend into the central hole. In another embodiment, the number of grinding mechanisms 40 can also be three, four or more. The grinding mechanisms 40 can be arranged on both sides of the worktable 20 in any way, as long as at least two grinding mechanisms 40 can be aligned with both ends of the shaft part 01 at the same time.

[0037] In one embodiment, the grinding mechanism 40 includes a spindle 41, a grinding rod 42, and a grinding wheel 43. The grinding rod 42 extends from the spindle 41, and the grinding wheel 43 is mounted on the free end of the grinding rod 42. The spindle 41 drives the grinding rod 42 and the grinding wheel 43 to rotate as a whole. The shaft part 01 is rotated by the part support mechanism 30. When performing internal thread grinding, the grinding rod 42 moves relative to the shaft part 01 along the centerline o1 (labeled "lateral" in the figure), so that the grinding wheel 43 can traverse the entire internal thread travel range of the shaft part 01. When performing internal thread grinding, the grinding wheel 42 is also controlled to move radially along the shaft part 01 to grind the internal thread.

[0038] In one embodiment, the grinding mechanism 40 is provided with an angle adjustment structure (not shown in the figure). While keeping the centerline o1 of the shaft part 01 constant, the angles of the grinding rods 42 on both sides are adjusted so that the centerlines o2 of the grinding rods 42 have the same angle relative to the centerline o1, thereby grinding the thread surface with an inclined thread profile angle. In another embodiment, the part support mechanism 30 may also be provided with an angle adjustment structure (not shown in the figure). While keeping the centerline o2 of the grinding rods 42 on both sides constant, the angle of the shaft part 01 is adjusted so that the centerlines o2 of the grinding rods 42 on both sides have the same angle relative to the centerline o1, which can also be applied to thread profile angles. In another embodiment, the angles of both grinding rods 42 of the grinding mechanism 40 may be adjustable.

[0039] In one embodiment, during the grinding process, in order to enable the grinding wheel 43 to move within the threaded stroke range in the central hole of the shaft part 01, only the worktable 20 can be configured to move horizontally along the center line o1 of the shaft part 01 (shown as "lateral" in the figure), or only the grinding mechanisms 40 on both sides can be configured to move horizontally along the center line o1 of the shaft part 01, or both the worktable 20 and the grinding mechanism 40 can be configured to move horizontally along the center line o1 of the shaft part 01.

[0040] In one embodiment, to facilitate the horizontal alignment of the centerline o1 of the shaft part 01 with the grinding rods 42 of the grinding mechanism 40 on both sides of the worktable 20, only the worktable 20 is configured to move horizontally along the direction perpendicular to the centerline o1 of the shaft part 01 (shown as "longitudinal" in the figure). Alternatively, only the grinding mechanisms 40 on both sides can be configured to move horizontally along the direction perpendicular to the centerline o1 of the shaft part 01. Or, both the worktable 20 and the grinding mechanism 40 can be configured to move horizontally along the direction perpendicular to the centerline o1 of the shaft part 01.

[0041] In one embodiment, to facilitate the vertical alignment of the centerline o1 of the shaft part 01 with the grinding rods 42 of the grinding mechanism 40 on both sides of the worktable 20, the grinding mechanism 40 on both sides is configured to be able to move in the vertical direction (shown as "vertical" in the figure).

[0042] In one embodiment, such as Figure 4 As shown, if the grinding wheels 43 of the grinding mechanism 40 on both sides of the worktable 20, which are used to grind shaft parts 01 at the same time, have the same coarse and fine abrasive grains, the grinding wheel with coarser abrasive grains can grind a section of internal thread first, and then the grinding wheel with finer abrasive grains can perform fine grinding on the coarsely ground internal thread section. During this process, there is a working time, that is, the grinding wheel performs coarse grinding on the internal thread that has not been ground, while the coarsely ground internal thread is simultaneously finely ground by another grinding wheel, thereby improving the grinding efficiency.

[0043] In another embodiment, such as Figure 4 As shown, if the grinding wheels 43 on both sides of the worktable 20 have the same abrasive grain size, the grinding working areas of each grinding wheel 43 can be non-overlapping. This means the internal threads to be ground are distributed between the grinding wheels 43 on both sides. Since a pair of grinding wheels 43 simultaneously grinds different sections of the internal threads for at least a certain period, grinding efficiency is improved. In this case, since both grinding wheels 43 can start grinding from any position between the two ends of the shaft-like part, the limit grinding position of the grinding wheel does not need to extend to the other end of the shaft-like part furthest from it. Therefore, it is unnecessary to make the grinding rod long, avoiding the problem of deformation caused by excessive load arm on the grinding rod.

[0044] In one embodiment, the part support mechanism 30 and the worktable 20 are connected in a relatively rotatable manner, such as... Figure 3 As shown, the part support mechanism 30 can rotate relative to the worktable 20 about a vertical axis x, thereby driving the shaft part 01 to rotate about the axis x, allowing the shaft part 01 to rotate in a horizontal plane. For example, the rotation range of the part support mechanism 30 is set to 180 degrees, thereby ensuring that the positions of the two ends of the shaft part 01 can be switched between the grinding rod 42 positions of the grinding mechanisms 40 on both sides.

[0045] The controller is used to control the rotation of the shaft-like parts driven by the part support mechanism 30. When performing internal thread grinding, the controller controls the grinding rods of a pair of opposing grinding mechanisms to move relative to the shaft-like parts. "Opposite" means that the grinding rods of the pair of grinding mechanisms on both sides of the worktable can simultaneously extend into the central hole from both ends of the shaft-like parts to grind the internal threads. In reality, the axes of the grinding rods of the pair of grinding mechanisms do not coincide with the rotation axis x of the shaft-like parts. The axes of the grinding rods of the pair of grinding mechanisms may coincide or not. When the axes of the grinding rods of the pair of grinding mechanisms coincide, the grinding contact point between their grinding wheels and the internal threads is located on the same side of the circular cross-section of the central hole. When the axes of the grinding rods of the pair of grinding mechanisms do not coincide, the grinding contact point between their grinding wheels and the internal threads is located on different sides of the circular cross-section of the central hole.

[0046] In one embodiment, during the internal thread grinding operation, the controller controls a pair of grinding wheels to stop close to each other at the grinding start point, and controls the pair of grinding wheels to feed away from each other to the grinding end point. For example, as shown... Figure 5a As shown, the grinding starting point can be set in the middle region of the shaft-like part, thereby minimizing the length of a pair of grinding rods, such as... Figure 5b As shown, the grinding endpoint can be located at either end of the shaft-like part. It should be noted that the "middle region" is not the ideal midpoint along the length of the center hole. Since the threaded surface of the internal thread cannot be located at the ideal midpoint, and since the two grinding wheels cannot simultaneously be located at the ideal midpoint, the "middle region" is only the area near the ideal midpoint, as long as the required length of the grinding rod can be minimized. Those skilled in the art will understand that in this embodiment, the grinding starting point can also be any position between the two ends of the shaft-like part, and the grinding endpoint is associated with the starting point of the internal thread.

[0047] In another embodiment, during the internal thread grinding operation, the controller controls a pair of grinding wheels to stop at the grinding start point, moving them away from each other, and then controls the pair of grinding wheels to feed towards each other until the grinding end point. For example, as shown... Figure 6a As shown, the grinding starting point can be set at both ends of the shaft-like part, such as... Figure 6b As shown, the grinding endpoint can be located in the middle region of the shaft-like part, thereby minimizing the length of a pair of grinding rods. Those skilled in the art will understand that in this embodiment, the grinding start point is associated with the starting point of the internal thread, and the grinding endpoint can also be any position between the two ends of the shaft-like part.

[0048] exist Figure 5a , Figure 5b , Figure 6a and Figure 6bIn the illustrated embodiment, the grinding wheels of a pair of opposing grinding rods can have the same grit size. In this case, the internal thread grinding is completed when each grinding wheel moves from the grinding start point to the grinding end point. Alternatively, the grinding wheels of a pair of opposing grinding rods can have different grit sizes. In this case, after each grinding wheel moves from the grinding start point to the grinding end point, only a portion of the internal thread is coarsely ground, causing the part support mechanism 30 to rotate relative to the worktable 20 about the vertical axis x. This allows the two ends of the shaft part 01 to switch between the positions of a pair of opposing grinding rods, and controls one grinding rod to perform fine grinding on the coarsely ground internal thread portion.

[0049] In one embodiment, during internal thread grinding, the controller controls a pair of grinding wheels to stop close to each other at the grinding start point, and then controls the pair of grinding wheels to move synchronously to the grinding end point while remaining close to each other. This is applicable when the grinding wheels of a pair of opposing grinding rods have different grit sizes. For example, as... Figure 7a As shown, the grinding starting point can be set at one end of the shaft-like part, such as... Figure 7b As shown, the grinding endpoint can be set at the other end of the shaft part. The grinding wheel on the right has coarser abrasive grains, while the grinding wheel on the left has finer abrasive grains. As the grinding wheels move from the grinding start point to the grinding endpoint, the grinding wheel on the right first performs coarse grinding of the internal thread, while the grinding wheel on the left simultaneously completes fine grinding.

[0050] In one embodiment, each grinding wheel can move continuously from the grinding start point to the grinding end point, or it can move intermittently, stopping and starting. With this configuration, when the grinding wheels of a pair of opposing grinding rods have different internal thread strokes to grind, the controller can control the grinding wheel with the longer stroke to move continuously, while controlling the grinding wheel with the shorter stroke to move intermittently. This ensures that both grinding wheels reach their respective grinding end points simultaneously and stop grinding, guaranteeing that both grinding wheels can simultaneously apply grinding load to the shaft part. This creates a load balance between the position where the grinding load is applied by the two grinding wheels and the support force provided by the part support mechanism to the shaft part, improving the rotational support stability of the shaft part during the grinding process.

[0051] The descriptions of the embodiments herein, including any references to directions and orientations, are for ease of description only and should not be construed as limiting the scope of the invention. The description of preferred embodiments involves combinations of features, which may exist independently or in combination; the invention is not particularly limited to the preferred embodiments. The scope of the invention is defined by the claims.

[0052] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An internal thread grinding machine for grinding internal threads on shaft-type parts, the shaft-type parts having a through-hole, and the internal thread being disposed on the inner surface of the through-hole around its centerline, characterized in that, The internal thread grinder comprises a bed, a worktable, a part supporting mechanism, at least two grinding mechanisms and a controller, the worktable and the at least two grinding mechanisms are arranged on the bed, the grinding mechanisms are arranged on both sides of the worktable respectively, the part supporting mechanism is arranged on the worktable, the shaft part is rotationally supported by the part supporting mechanism around the center line and is in an exposed state at both ends, each grinding mechanism is provided with a grinding rod extending towards the part supporting mechanism, so that a pair of opposite grinding rods arranged on both sides of the worktable can extend into the central hole from both ends of the shaft part to grind the internal thread, wherein the controller is used to control the part supporting mechanism to drive the shaft part to rotate around the center line, and control the relative movement between the pair of opposite grinding rods and the shaft part to perform the internal thread grinding action, the internal thread grinding action is that the pair of opposite grinding rods extend into the central hole from both ends of the shaft part to grind the internal thread synchronously, the grinding wheels of the pair of opposite grinding rods move at least in the direction of the center line from the respective grinding starting point to the grinding ending point to complete the grinding process of the internal thread. The controller is used to control the grinding wheels of the pair of opposite grinding rods to stop at the grinding starting point and move to the grinding ending point in the direction away from each other, or the controller is used to control the grinding wheels of the pair of opposite grinding rods to stop at the grinding starting point and move to the grinding ending point in the direction close to each other. The axes of the pair of opposite grinding rods do not coincide with each other, so that the grinding contact points of the grinding wheels of the pair of opposite grinding rods and the internal thread are located at different side positions of the central hole cross section.

2. The box thread grinder of claim 1 wherein, If the controller is used to control the grinding wheels of the pair of opposite grinding rods to stop at the grinding starting point and move to the grinding ending point in the direction away from each other, the grinding starting point is located in the middle region of the central hole of the shaft part, and the grinding ending point is located in the end region of the central hole of the shaft part.

3. The box thread grinder of claim 1 wherein, If the controller is used to control the grinding wheels of the pair of opposite grinding rods to stop at the grinding starting point and move to the grinding ending point in the direction close to each other, the grinding ending point is located in the middle region of the central hole of the shaft part, and the grinding starting point is located in the end region of the central hole of the shaft part.

4. The box thread grinder of claim 1 wherein, The pair of opposite grinding rods have grinding wheels with the same grit size; or the pair of opposite grinding rods have grinding wheels with different grit sizes.

5. The box thread grinder of claim 4 wherein, When the pair of opposite grinding rods have grinding wheels with different grit sizes, the grinding wheels of the pair of opposite grinding rods move in the same direction at least in the direction of the center line, so that the internal thread is ground by the grits with larger size and the grits with smaller size of the grinding wheels of the pair of opposite grinding rods in turn.

6. The box thread grinder according to any one of claims 1-5, wherein, The part supporting mechanism is rotationally arranged on the worktable around the vertical rotation shaft, so that the positions of the two ends of the shaft part can rotate in the horizontal plane, thereby switching between the positions of the pair of opposite grinding rods.

7. The female thread grinder of claim 1, wherein, The part supporting mechanism and / or the grinding mechanism are provided with angle adjustment structures, so that the included angle between the grinding rod and the center line of the shaft part is formed to adapt to the thread angle of the internal thread.

8. The female thread grinder of claim 1, wherein, In the process of the synchronous grinding of the internal thread, any one of the pair of opposite grinding rods adopts continuous movement, reciprocating movement or intermittent movement between the grinding start point and the grinding end point.

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