CN110666637A - Horizontal double-spindle bearing ring grinding machine - Google Patents

Abstract

The invention relates to a horizontal double-spindle bearing ring grinding machine, which comprises a bed, an installation platform, a first main shaft, a measuring device, a second main shaft, an X-direction moving platform, an electromagnetic centerless fixture, an electric spark grinding wheel shaping device and an electric spark electrode The repairing device, the upper part of the bed is fixed with a horizontal installation platform by bolts, and an X-direction parallel guide rail is arranged on one side of the X-axis on the installation platform. The type device is arranged horizontally from left to right on the other side of the X-axis of the installation platform, the loading and unloading device is arranged at the left end of the installation platform, the measuring device is arranged between the first main shaft and the second main shaft, and the EDM electrode is trimmed. The device is arranged on the right side of the second main shaft; the first main shaft and the second main shaft are both provided with an on-line electrolytic sharpening device. The invention can realize the semi-fine grinding and fine grinding of the bearing ring in the case of one clamping.

Description

A horizontal double-spindle bearing ring grinder

technical field

The invention relates to bearing ring raceway processing equipment, in particular to a horizontal double-spindle bearing ring grinding machine.

Background technique

Bearings are an important component in contemporary machinery and equipment. Its main function is to support the mechanical rotating body, reduce the friction coefficient during its movement, and ensure its rotation accuracy. During the operation of mechanical equipment, especially during the operation of some important equipment, regular maintenance and replacement of bearings is a necessary means to ensure the normal operation of the equipment. It is even required to replace all the bearings of the same type on the equipment on a regular basis. This requires a reasonable prediction of the service life of these bearings. When predicting the service life of the entire batch of bearings, the same type of bearings in the entire batch In order to ensure the reasonable and effective prediction results, the indicators have a high degree of consistency.

In the grinding process of the inner ring of the bearing, the semi-finishing and fine grinding of the inner ring raceway play a decisive role in ensuring the consistency of the inner ring raceway. Existing inner ring raceway grinders, including CNC inner ring raceway grinders, basically use a single spindle processing method. When batch processing of bearing rings, one machine tool corresponds to a fixed process, semi-finishing and The fine grinding is separated, so the processing efficiency is high; but when reflecting the consistency of the bearing inner ring raceway, due to the clamping error and the error between the size and shape of the grinding head between different machine tools, even if the qualified product is processed There must be some small gaps between them, which will affect the consistency of the entire batch of products.

At present, in the domestic processing of the inner ring raceway, the more advanced processing method is the use of automatic assembly lines, but the two processes of semi-finishing and fine-grinding are also completed on different equipment, which must also go through two up and down processes. No matter how precise the clamping and positioning mechanism is, there must still be a certain positioning error during the second clamping process, which results in poor consistency of the outer dimensions of the inner ring raceway surface. It is impossible to completely eliminate this inconsistency, thus affecting the overall quality of the bearing after assembly, and the overall consistency of the produced bearing is not very good, thus affecting the prediction of bearing life.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a horizontal double-spindle bearing ring grinding machine. The on-line electrolytic sharpening technology of the grinding head realizes the semi-finishing and fine grinding of the bearing inner ring raceway under the condition of one clamping, which can reduce the clamping error during the machining process of the bearing inner ring raceway. The grinding heads of each process use the same dressing mechanism, and the grinding heads after dressing have good consistency, so as to obtain products with relatively uniform processing dimensions.

To achieve the above object, the present invention adopts the following technical solutions:

A horizontal double-spindle bearing ring grinder, comprising a bed, an installation platform, a first spindle, a measuring device, a second spindle, an X-direction moving platform, an electromagnetic centerless fixture, an EDM grinding wheel shaping device and an EDM electrode trimming device The upper part of the bed is fixed with a horizontal installation platform by bolts, and an X-direction parallel guide rail is arranged on one side of the X-axis on the installation platform, and an X-direction screw nut pair is arranged between the parallel guide rails. The X-direction The mobile platform is arranged on the parallel guide rails and runs on the parallel guide rails, the lower part of the X-direction mobile platform is fixedly connected with the nut connecting plate of the X-direction screw nut pair, (the X-direction mobile platform is respectively provided with a first Y-direction The moving mechanism and the second Y-direction moving mechanism, the first Y-direction moving mechanism and the second Y-direction moving mechanism are respectively provided with a Y-direction carriage, and the electromagnetic centerless clamp is arranged on the upper left of the X-direction moving platform through the first Y-direction moving mechanism. On the side, the EDM grinding wheel shaping device is arranged on the upper right side of the X-direction moving platform through the second Y-direction moving mechanism, and the motor used to drive the X-direction lead screw to rotate is arranged on the installation platform at the right end of the X-direction lead screw, so The first main shaft, the second main shaft and the EDM electrode trimming device are arranged horizontally on the other side of the X-axis of the installation platform from left to right, and the measuring device is arranged between the first main shaft and the second main shaft, The EDM electrode trimming device is arranged on the right side of the second spindle; the first spindle and the second spindle are composed of the grinding wheel motorized spindle, the spindle seat, the grinding wheel shaft, the insulating coupling and the axle box, wherein the grinding wheel motorized spindle passes through The spindle seat is fixedly installed on the installation platform, the grinding wheel shaft coaxial with the grinding wheel electric spindle is passed through the axle box, the axle box is set above the installation platform through the insulating plate, and one end of the grinding wheel shaft is connected to the grinding wheel electric motor through an insulating coupling. The output end of the main shaft is insulated and fixed, and the other end of the grinding wheel shaft is installed with a grinding wheel, the grinding wheel is a metal bond diamond grinding wheel, and the grinding wheel is electrically connected with the positive pole of the high-frequency pulse power supply. The axis of the grinding wheel axis of the main shaft is parallel and of the same height.

The first spindle and the second spindle are all provided with an on-line electrolytic sharpening device, and the on-line electrolytic sharpening device includes an X-axis moving mechanism, an insulating support, an electrolytic negative electrode and an electrolytic spray head, and the X-axis moving mechanism It consists of a mounting seat, a guide rail, a linear motor and a moving plate. The mounting seat is fixed on the upper end of the axle box. One end of the mounting seat is provided with a linear motor, and the other end is provided with a guide rail. The moving plate is driven by the linear motor and is on the guide rail. In operation, the upper end of the insulating support is fixedly connected with the moving plate, and the lower end is provided with an electrolytic negative electrode. The electrolytic negative electrode is an arc-shaped plate made of red copper as a whole. The negative pole of the frequency pulse power supply is connected, the electrolysis nozzle for spraying the electrolyte is penetrated at the lower end of the insulating support, and the outlet of the electrolysis nozzle is located between the electrolysis negative electrode and the grinding wheel.

The EDM grinding wheel shaping device includes an EDM negative electrode, an electrode electric spindle, and an EDM nozzle. The spark negative electrode is installed at the output end of the electric spindle, the spark electrode is connected with the negative pole of the high-frequency pulse power supply, and the spark nozzle for spraying the spark electrolyte is fixed above the spark negative electrode.

The measuring device includes a Z-direction displacement mechanism, a Z-direction support plate, a grating ruler, a measuring bracket and a measuring head. The Z-direction displacement mechanism is composed of a vertical arm, a parallel guide rail, a screw nut pair and a drive motor. Parallel guide rails are arranged on the side, the lead screw nut pair is arranged between the parallel guide rails, the driving motor is arranged at the top of the vertical arm and is connected with the lead screw of the lead screw nut pair through the deceleration mechanism. The nut connecting plate is fixed and runs on the parallel guide rail. The measuring head is arranged on the measuring bracket, the measuring bracket is fixed on the Z-direction support plate and is located on the side of the vertical arm facing the X moving platform, and the scale grating of the grating ruler is fixed. Set on the other side of the vertical arm, the grating reading head of the grating ruler is fixedly connected with the Z-direction support plate through the connecting plate.

The electromagnetic centerless clamp is arranged on the carriage of the first Y-direction displacement mechanism through a clamp seat whose angle can be adjusted horizontally, and the motor for driving the rotation of the centerless clamp is disposed above the clamp seat through the motor seat.

The EDM electrode trimming device is composed of a base, a tool rest seat, a tool rest and a turning tool, the base is arranged on the right side of the second main shaft, the lower end of the base is fixedly connected with the installation platform, and the upper end is provided with a tool rest seat , the upper end face of the tool holder seat is provided with a T-shaped groove, the tool holder is installed in the T-shaped groove of the tool holder seat through T-shaped bolts, the side of the tool holder is provided with an open slot for accommodating the turning tool, and the open groove is located in the tool holder. The upper side wall is provided with fastening bolts for clamping the turning tool.

The principle of the invention is as follows: by adopting double spindles, the semi-finishing and fine grinding of the bearing ring can be completed in one clamping; the designed on-line electrolytic sharpening device is used for sharpening the grinding wheel, and at the same time, it is convenient for grinding debris The discharge of the electric spark; the electric spark shaping device is used for the repairing of the grinding wheel, and it is used in conjunction with the online electrolytic sharpening device and the measuring device, and the repairing efficiency is high.

The beneficial effects of the invention are as follows: the structure of the invention is simple and reasonable, the semi-fine grinding and fine grinding of the bearing ring can be completed in one clamping, the processing efficiency is high, and the processed products have high precision and good dimensional consistency.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the present invention.

Figure 2 is a top view of the present invention.

FIG. 3 is a view from the direction A-A in FIG. 2 .

FIG. 4 is a view from the direction B-B in FIG. 2 .

FIG. 5 is a schematic diagram of the second spindle and its on-line electrolytic sharpening device.

Fig. 6 is the A-A view of the second spindle and its in-line electrolytic sharpening device.

FIG. 7 is a schematic diagram of an insulating support in an on-line electrolytic sharpening device.

FIG. 8 is a schematic diagram of the measurement device.

FIG. 9 is a top view of the measuring device.

Fig. 10 is a schematic diagram of an EDM grinding wheel shaping device.

FIG. 11 is a top view of the electromagnetic centerless clamp and the electric spark.

In the figure, 1. Machine bed, 2. Installation platform, 3. First spindle, 4. Measuring device, 5. Second spindle, 6. X-direction mobile platform, 601, X-direction parallel guide rail, 602, X-direction lead screw Nut pair, 603, motor, 604, first Y-direction moving mechanism, 605, second Y-direction moving mechanism, 7, electromagnetic centerless clamp, 8, EDM grinding wheel shaping device, 9, EDM electrode trimming device, 11, Online electrolytic sharpening device;

402, Z-direction pallet, 403, grating ruler, 404, measuring bracket, 405, measuring head, 411, vertical arm, 412, Z-direction parallel guide rail, 413, screw nut pair, 414, drive motor;

501, grinding wheel electric spindle, 502, spindle seat, 503, grinding wheel shaft, 504, insulating coupling, 505, axle box, 506, grinding wheel;

701, fixture seat;

801, EDM negative electrode, 802, Electrode electric spindle, 803, EDM nozzle, 804, Fixed support;

901, base, 902, tool holder, 903, tool holder, 904, turning tool;

1102, insulating bracket, 1103, electrolysis negative electrode, 1104, electrolysis nozzle, 1111, mounting seat, 1112, guide rail, 1113, linear motor, 1114, moving plate.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings.

As shown in Figures 1 to 5, a horizontal double-spindle bearing ring grinder includes a bed 1, an installation platform 2, a first spindle 3, a measuring device 4, a second spindle 5, an X-direction moving platform 6, an electromagnetic centerless The fixture 7, the EDM grinding wheel shaping device 8, the EDM electrode trimming device 9 and the loading and unloading device 10, the upper part of the bed 1 is fixed with a horizontal installation platform 2 by bolts, and the upper X axis of the installation platform 2 is on one side. An X-direction parallel guide rail 601 is provided, and an X-direction lead screw nut pair 602 is arranged between the parallel guide rails 601. The X-direction moving platform 6 is arranged on the parallel guide rail 601 and runs on the parallel guide rail 601. The X-direction moving platform 6 The lower part is fixedly connected with the nut connecting plate of the X-direction screw nut pair 602. The X-direction moving platform 6 is respectively provided with a first Y-direction moving mechanism 604 and a second Y-direction moving mechanism 605. The first Y-direction moves The mechanism 604 and the second Y-direction moving mechanism 605 are respectively provided with Y-direction carriages, the electromagnetic centerless clamp 7 is arranged on the upper left side of the X-direction moving platform 6 through the first Y-direction moving mechanism 604, and the EDM grinding wheel shaping device 8 passes through the first Y-direction moving mechanism 604. Two Y-direction moving mechanisms 605 are arranged on the upper right side of the X-direction moving platform 6, the motor 603 for driving the X-direction screw to rotate is arranged on the installation platform 2 at one end of the X-direction lead screw, the first spindle 3. The second main shaft 5 and the EDM electrode trimming device 9 are arranged horizontally from left to right on the other side of the axial direction of the installation platform 2X, and the measuring device 4 is arranged between the first main shaft 3 and the second main shaft 5 , the EDM electrode trimming device 9 is arranged on the right side of the second main shaft 5; the first main shaft 3 and the second main shaft 5 are composed of a grinding wheel electric main shaft 501, a main shaft seat 502, a grinding wheel shaft 503, an insulating coupling 504, The shaft box 505 is formed, wherein the grinding wheel electric spindle 501 is fixedly installed on the installation platform 2 through the main shaft seat 502, the grinding wheel shaft 503 coaxial with the grinding wheel electric spindle 501 is penetrated in the shaft box 505, and the shaft box 505 is arranged on the installation platform 505 through an insulating plate. Above the platform, one end of the grinding wheel shaft 503 is insulated and fixed to the output end of the grinding wheel electric spindle 501 through an insulating coupling 504, and the other end of the grinding wheel shaft 503 is installed with a grinding wheel 506, which is a metal bond diamond grinding wheel, so The grinding wheel 506 is electrically connected to the positive pole of the high-frequency pulse power supply, and the axes of the grinding wheel shafts 503 of the first spindle 3 and the second spindle 5 are parallel and have the same height.

As shown in Figures 5, 6, and 7, the first spindle 3 and the second spindle 5 are provided with an on-line electrolytic sharpening device 11, and the on-line electrolytic sharpening device 11 includes an X-axis moving mechanism, an insulating support 1102, the electrolytic negative electrode 1103 and the electrolytic shower head 1104, the X-axis moving mechanism is composed of a mounting seat 1111, a guide rail 1112, a linear motor 1113 and a moving plate 1114, the mounting seat 1111 is fixedly arranged on the upper end of the axle box 505, and the mounting seat 1111 is above One end is provided with a linear motor 1113, the other end is provided with a guide rail 1112, the moving plate 1114 is driven by the linear motor 1113 and runs on the guide rail 1112, the upper end of the insulating support 1102 is fixed with the moving plate 1114, and the lower end is provided with an electrolytic negative electrode 1103, the electrolytic negative electrode 1103 is an arc-shaped plate made of red copper as a whole, and the electrolytic negative electrode 1103 is coaxially arranged on one side of the grinding wheel shaft 503 and is connected to the negative electrode of the high-frequency pulse power supply. The electrolytic shower head 1104 is penetrated at the lower end of the insulating support 1102 , and the outlet of the electrolytic shower head 1104 is located between the electrolytic negative electrode 1103 and the grinding wheel 506 .

As shown in FIGS. 2 , 4 , 10 and 11 , the EDM grinding wheel shaping device 8 includes an EDM negative electrode 801 , an electrode electric spindle 802 , and an EDM nozzle 803 , and the electrode electric spindle 801 passes through a fixed support 804 Installed on the carriage of the second Y-direction moving mechanism 605, the electric spark negative electrode 801 made of red copper is installed on the output end of the electrode electric spindle 802, and the electric spark electrode 801 is connected with the negative pole of the high-frequency pulse power supply for spraying. The spark nozzle 803 of the spark electrolyte is fixedly arranged above the negative electrode 801 of the spark.

As shown in Figures 2, 3, 8, and 9, the measuring device 4 includes a Z-direction displacement mechanism, a Z-direction support plate 402, a grating ruler 403, a measuring bracket 404 and a measuring head 405. The Z-direction displacement mechanism is composed of a vertical The arm 411, the parallel guide rail 412, the screw nut pair 413 and the drive motor 414 are formed. The vertical arm 411 is provided with a parallel guide rail 412 on one side, the screw nut pair 413 is arranged between the parallel guide rails 412, and the drive motor 414 is arranged on the vertical arm 411. The top end is connected with the lead screw of the lead screw nut pair 413 through the deceleration mechanism. The Z-direction support plate 402 is fixedly connected with the nut connecting plate of the lead screw nut pair 413 and runs on the parallel guide rail 412. The measuring head 405 is arranged at On the measuring bracket 404, the measuring bracket 404 is fixed on the Z-direction support plate 402 and is located on the side of the vertical arm 411 facing the X moving platform 6, the scale grating of the grating ruler 403 is fixedly arranged on the other side of the vertical arm 411, and the grating ruler 403 The grating reading head is fixedly connected with the Z-direction support plate 402 through the connecting plate.

As shown in Figures 2, 4, and 11, the electromagnetic centerless clamp 7 is set on the carriage of the first Y-direction displacement mechanism 604 through a clamp seat 701 whose angle can be adjusted horizontally, and the motor used to drive the rotation of the centerless clamp passes through the motor The seat is provided above the clamp seat 701 .

As shown in FIGS. 2 , 5 , 6 and 7 , the EDM electrode trimming device 9 is composed of a base 901 , a tool holder seat 902 , a tool holder 903 and a turning tool 904 , and the base 901 is arranged on the second spindle 5 On the right side, its lower end is fixedly connected with the installation platform 2, its upper end is provided with a tool rest seat 902, the upper end surface of the tool rest seat 902 is provided with a T-shaped groove, and the tool rest 903 is installed on the T-shaped of the tool rest seat 902 through T-shaped bolts In the groove, the side of the tool holder 903 is provided with an open slot for accommodating the turning tool 904 .

The parts of the present invention that are not described in detail are prior art.

Claims (5)

1. A horizontal double-spindle bearing ring grinder, comprising a bed (1), an installation platform (2), a first main shaft (3), a measuring device (4), a second main shaft (5), and an X-direction moving platform (6), electromagnetic centerless clamp (7), EDM grinding wheel shaping device (8) and EDM electrode trimming device (9), the upper part of the bed (1) is fixed with a horizontal installation platform (2) by bolts. ), an X-direction parallel guide rail (601) is arranged on one side of the X-axis of the installation platform (2), and an X-direction screw nut pair (602) is arranged between the parallel guide rails (601). The X-direction mobile platform ( 6) Set on the parallel guide rail (601) and run on the parallel guide rail (601), the lower part of the X-direction moving platform (6) is fixedly connected with the nut connecting plate of the X-direction screw nut pair (602), and is characterized by: The X-direction moving platform (6) is respectively provided with a first Y-direction moving mechanism (604) and a second Y-direction moving mechanism (605), a first Y-direction moving mechanism (604), a second Y-direction moving mechanism (605) are respectively provided with Y-direction carriages, the electromagnetic centerless clamp (7) is arranged on the upper left side of the X-direction moving platform (6) through the first Y-direction moving mechanism (604), and the EDM grinding wheel shaping device (8) passes through The second Y-direction moving mechanism (605) is arranged on the upper right side of the X-direction moving platform 6, and the motor (603) for driving the X-direction screw to rotate is arranged on the installation platform (2) at one end of the X-direction lead screw , the first main shaft (3), the second main shaft (5), and the EDM electrode trimming device (9) are arranged horizontally from left to right on the other side of the X-axis of the installation platform (2), and the The measuring device (4) is arranged between the first main shaft (3) and the second main shaft (5), and the electric spark electrode trimming device (9) is arranged on the right side of the second main shaft (5); the first main shaft ( 3) The second spindle (5) is composed of a grinding wheel motorized spindle (501), a spindle seat (502), a grinding wheel shaft (503), an insulating coupling (504), and an axle box (505). 501) is fixedly installed on the installation platform (2) through the spindle seat (502), the grinding wheel shaft (503) coaxial with the grinding wheel electric spindle (501) is passed through the axle box (505), and the axle box 505 is arranged through the insulating plate Above the installation platform (2), one end of the grinding wheel shaft (503) is insulated and fixed to the output end of the grinding wheel motor spindle (501) through an insulating coupling (504), and the other end of the grinding wheel shaft (503) is installed with a Grinding wheel (506), the grinding wheel (506) is a metal bond diamond grinding wheel, the grinding wheel (506) is electrically connected with the positive pole of the high-frequency pulse power supply, the first spindle (3), the second spindle (5) The axis of the grinding wheel shaft (503) is parallel and of equal height; The first main shaft (3) and the second main shaft (5) are both provided with an on-line electrolytic sharpening device (11), and the on-line electrolytic sharpening device (11) includes an X-axis moving mechanism, an insulating support (1102) ), an electrolytic negative electrode (1103) and an electrolytic shower head (1104), the X-axis moving mechanism is composed of a mounting seat (1111), a guide rail (1112), a linear motor (1113) and a moving plate (1114), the mounting seat (1111) ) is fixedly arranged on the upper end of the axle box (505), a linear motor (1113) is arranged on one end of the mounting seat (1111), and a guide rail (1112) is arranged at the other end, and the moving plate (1114) is driven by the linear motor (1113). and run on the guide rail (1112), the upper end of the insulating support (1102) is fixedly connected with the moving plate (1114), and the lower end is provided with an electrolytic negative electrode (1103), the electrolytic negative electrode (1103) as a whole is made of red copper Arc-shaped plate, the electrolytic negative electrode (1103) is coaxially arranged on one side of the grinding wheel shaft (503) and connected to the negative electrode of the high-frequency pulse power supply, and the electrolytic spray head (1104) for spraying the electrolyte is penetrated through the insulating support At the lower end of (1102), the outlet of the electrolysis nozzle (1104) is located between the electrolysis negative electrode (1103) and the grinding wheel (506). 2. A horizontal double-spindle bearing ring grinding machine according to claim 1, characterized in that: the EDM grinding wheel shaping device (8) 8 comprises an EDM negative electrode (801), an electrode electric spindle (802) ), an EDM nozzle (803), the electrode spindle (801) is mounted on the carriage of the second Y-direction moving mechanism (605) through a fixed support (804), and the EDM negative electrode made of red copper ( 801) is installed at the output end of the electrode electric spindle (802), the spark electrode (801) is connected to the negative electrode of the pulse power supply, and the spark nozzle (803) for spraying the spark electrolyte is fixedly arranged on the negative electrode of the spark (801). 801) above. 3. A horizontal double-spindle bearing ring grinder according to claim 1, characterized in that: the measuring device (4) comprises a Z-direction displacement mechanism, a Z-direction support plate (402), a grating ruler (403) ), a measuring bracket (404) and a measuring head (405), the Z-direction displacement mechanism is composed of a vertical arm (411), a parallel guide rail (412), a screw nut pair (413) and a drive motor (414), the vertical arm (411) One side is provided with parallel guide rails (412), the lead screw nut pair (413) is set between the parallel guide rails (412), and the drive motor (414) is set at the top of the vertical arm (411) and is connected to the lead screw through a deceleration mechanism The lead screw of the nut pair (413) is connected, the Z-direction support plate (402) is fixedly connected with the nut connecting plate of the lead screw nut pair (413) and runs on the parallel guide rail (412), the measuring head (405) It is arranged on the measuring bracket (404), the measuring bracket (404) is fixed on the Z-direction support plate (402) and is located on the side of the vertical arm (411) facing the X moving platform (6), the scale of the grating ruler (403) The grating is fixedly arranged on the other side of the vertical arm (411), and the grating reading head of the grating ruler (403) is fixedly connected with the Z-direction support plate (402) through the connecting plate. 4. A horizontal dual-spindle bearing ring grinding machine according to claim 1, wherein the electromagnetic centerless clamp (7) is arranged in the first Y direction through a clamp seat (701) whose angle can be adjusted horizontally. On the carriage of the displacement mechanism (604), the motor for driving the rotation of the centerless clamp is arranged above the clamp base (701) through the motor base. 5. A horizontal double-spindle bearing ring grinding machine according to claim 1, characterized in that: the EDM electrode trimming device (9) consists of a base (901), a tool holder (902), a tool A frame (903) and a turning tool (904) are formed, the base (901) is arranged on the right side of the second spindle (5), its lower end is fixedly connected with the mounting platform (2), and its upper end is provided with a tool holder seat (902) ), the upper end face of the tool holder (902) is provided with a T-shaped groove, and the tool holder (903) is installed in the T-shaped groove of the tool holder (902) through T-bolts. To accommodate the opening slot of the turning tool (904), the side wall of the opening slot located at the upper part of the tool holder (903) is provided with a fastening bolt for clamping the turning tool (904).

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