Machine tool skylight structure

Abstract

The present application provides a machine tool skylight structure, which belongs to the technical field of machine tool equipment. The machine tool skylight structure can solve the problem of inconvenient feeding on the top of the machine tool during normal machining. The machine tool skylight structure comprises a front-rear telescopic shield arranged on the top of the machine tool, a movable base arranged on the top of the machine tool, a front end of the shield fixed on the machine tool, a rear end of the shield fixed with a locking base, a movable bolt inserted in the locking base, the bolt in the form of a middle-diameter-reduced round rod, a hook plate fixed on the movable base, the hook plate provided with a plug-in part for the bolt, the plug-in part in the form of C and the opening facing forward, the width of the opening of the plug-in part smaller than the outer diameter of the bolt, and a positioning base fixed on the front end of the machine tool for the bolt, when the bolt is inserted into the positioning base, the plug-in part opposite to the reduced-diameter section of the bolt and the reduced-diameter section of the bolt capable of passing through the opening of the plug-in part. The skylight structure can make the feeding on the top of the machine tool convenient during normal machining, and the structure is simple and convenient to operate.

Description

Technical Field

[0001] This invention belongs to the field of machine tool equipment technology and relates to a machine tool skylight structure. Background Technology

[0002] High-end CNC machine tools possess multifunctional characteristics such as high speed, high precision, intelligence, composite processing, multi-axis linkage, and internet communication. Their development level is an important indicator of a country's modern industrialization. Existing ordinary CNC machining centers have relatively limited functions, which restricts the processing quality and efficiency of high-end parts. Five-axis machining centers, applied in the five-axis linkage machining industry, are CNC machine tools capable of processing precision and complex parts. These CNC machine tools provide a foundation for the development of my country's aerospace, military, high-precision medical device, cutting tool manufacturing, and mold manufacturing industries.

[0003] Currently, more and more machine tools are being used in flexible production lines. When machine tools are used in flexible production lines, the gantry lines that support the loading and unloading of the machine tools place high demands on the protective covers of the machine tools. Currently, many machine tools are protected in an open manner when used in flexible production lines. In this case, the machine tool cannot achieve a fully enclosed processing area, and the oil mist generated during machine processing will cause varying degrees of pollution to the environment.

[0004] For example, a vertical five-axis machine tool includes a frame with a cradle-type worktable inside for A-axis and C-axis rotation. The top of the frame has a window and a Y-axis moving seat, an X-axis moving seat on the Y-axis moving seat, and a Z-axis moving seat on the X-axis moving seat. A tool chuck is mounted at the lower end of the Z-axis moving seat. To reduce oil mist pollution, a skylight structure is usually installed on the top of the machine tool. For example, a pneumatic curtain skylight structure (publication number: CN222754992U) disclosed in Chinese patent literature is used to drive the curtain on the top of the machine tool. It includes mounting brackets, cylinders, and connecting components. Two sets of mounting brackets and cylinders are symmetrically fixed to the two sides of the top of the machine tool. The mounting brackets include a first mounting bracket and a second mounting bracket. The first and second mounting brackets have the same structure and are arranged in an L-shape. The first and second mounting brackets are laterally fixed to the front and rear edges of the top of the machine tool. The cylinders are laterally fixed between the first and second mounting brackets. The connecting components are fixed to the front of the curtain and connected at the top to the driving ends of the two cylinders.

[0005] In the aforementioned skylight structure, the rear side of the curtain is fixedly connected to the Y-axis moving seat. When the piston rod of the cylinder extends forward, the curtain extends forward to cover the top window of the machine tool; when the piston rod retracts backward, the curtain retracts backward to open the top window of the machine tool. Since the Y-axis, X-axis, and Z-axis moving seats are located behind the curtain, occupying a certain amount of space, and the curtain still occupies some Y-axis space after retracting, it may still partially obstruct the worktable, making loading and unloading difficult for the gantry robot. If the curtain is retracted forward to better avoid the worktable, for example, by fixing the front side of the curtain to the machine tool and the rear side to the cylinder piston rod, with the cylinder piston rod extending forward to retract the curtain, this would restrict the curtain's movement during extension, preventing it from moving synchronously with the Y-axis moving seat, thus hindering normal workpiece processing. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a machine tool skylight structure, which solves the technical problem of how to facilitate loading and unloading of materials from the top of the machine tool while ensuring normal processing.

[0007] The objective of this invention can be achieved through the following technical solutions: A machine tool skylight structure includes a retractable cover mounted on the top of the machine tool, and a movable seat that can move back and forth on the top of the machine tool. The front end of the cover is fixed to the machine tool, and a locking seat is fixed to the rear end of the cover. A movable pin is inserted into the locking seat. The pin is a round rod with a reduced diameter in the middle. A hook plate is fixed to the movable seat. The hook plate has a mating part for inserting the pin. The mating part is C-shaped and faces forward. The width of the opening of the mating part is smaller than the outer diameter of the pin. A positioning seat for inserting the pin is also fixed to the front end of the machine tool. When the pin is inserted into the positioning seat, the mating part is opposite to the reduced diameter section of the pin, and the reduced diameter section of the pin can pass through the opening of the mating part.

[0008] When the machine tool is processing a workpiece, the skylight is closed, the protective cover is in the extended state, the pin is inserted into the fitting part and the reduced diameter section of the pin is offset from the fitting part. Since the width of the opening of the fitting part is smaller than the outer diameter of the pin, the pin will not come out of the opening of the fitting part. The pin and the hook plate cooperate to fix the rear end of the protective cover to the moving seat. The rear end of the protective cover can move synchronously with the moving seat, so that the machine tool can process normally. When the workpiece is finished and needs to be loaded or unloaded, the moving seat moves forward, pushing the protective cover forward to retract. The locking seat and the pin move forward with the protective cover. When the pin is opposite to the positioning seat, the pin moves to insert into the positioning seat. At this time, the mating part is opposite to the reduced diameter section of the pin. The moving seat moves backward, and the reduced diameter section of the pin passes through the opening of the mating part, causing the pin to disengage from the hook plate. The moving seat will not pull the protective cover backward, but the pin is inserted into the positioning seat and the locking seat to keep the protective cover locked and prevent it from moving backward. After the moving seat moves backward to avoid the space above the worktable, the gantry robot can load and unload normally, and the protective cover does not gather at the rear with the moving seat to cause interference, making loading and unloading convenient. After loading and unloading are completed, the moving seat moves forward, and the reduced-diameter section of the pin passes through the opening of the fitting part, allowing the pin to enter the hook plate. Then, the pin moves, disengaging from the positioning seat. At this point, the reduced-diameter section of the pin is misaligned with the fitting part, preventing the pin from slipping out of the fitting part's opening. The pin engages with the hook plate to fix the rear end of the protective cover to the moving seat. The moving seat moves backward, extending the protective cover to close the skylight. Therefore, this skylight structure allows for convenient top loading and unloading while ensuring normal machine processing. Moreover, a single pin can lock and unlock two structures, resulting in a simple structure and convenient operation.

[0009] In the above-described machine tool skylight structure, the axial length of the reduced-diameter section of the pin is greater than the axial thickness of the mating part, and the width of the opening of the mating part is greater than the diameter of the reduced-diameter section of the pin. This allows the reduced-diameter section of the pin to pass smoothly through the opening of the mating part when they are aligned, enabling the skylight to open and close smoothly.

[0010] In the above-described machine tool skylight structure, a cylinder is fixed on the locking seat, and the piston rod of the cylinder is inserted into the locking seat and fixedly connected to the pin. The locking seat not only provides radial positioning and movement guidance for the pin, but also serves to fix the cylinder and protect its piston rod, thus serving multiple purposes. Furthermore, since both the pin and the cylinder are positioned on the locking seat, the accuracy and stability of the pin's movement are improved, allowing the skylight to open and close smoothly.

[0011] In the above-described machine tool skylight structure, a sliding bearing is fixed in the locking seat, and the pin is inserted into the sliding bearing. The sliding bearing reduces the frictional resistance when the pin slides, allowing the pin to slide smoothly and the skylight to open and close easily. This facilitates loading and unloading of materials from the top of the machine tool while ensuring normal processing.

[0012] In the aforementioned machine tool skylight structure, the positioning seat has a spherical surface, and the lower end of the pin has a spherical head. When the lower end of the pin is inserted into the positioning seat, the spherical head abuts against the spherical surface. The spherical head and spherical surface cooperate during the pin insertion with the positioning seat, reducing friction during the insertion process and minimizing the impact of assembly errors on the pin insertion and positioning seat connection, thus ensuring smooth opening and closing of the skylight.

[0013] In the aforementioned machine tool skylight structure, a connecting plate is fixedly connected to the locking seat. Two position sensors arranged axially along the pin are fixedly mounted on the connecting plate. An induction coil, capable of being sensed by the position sensors, is fixedly connected to the pin. A solenoid valve is installed between the cylinder and the air source. Both the solenoid valve and the position sensors are connected to the machine tool's controller. When the position sensor senses the induction coil, the controller controls the solenoid valve to close, stopping the cylinder's movement. The movement of the pin is controlled through the cooperation of the position sensor and the induction coil, facilitating automated control. When the cylinder drives the pin upwards, if the lower position sensor is opposite the induction coil, the solenoid valve closes, the cylinder stops supplying air, and the pin remains in its upward-moved state. When the cylinder drives the pin downwards, if the upper position sensor is opposite the induction coil, the solenoid valve closes, the cylinder stops supplying air, and the pin remains in its downward-moved state.

[0014] In the aforementioned machine tool skylight structure, the induction coil is located between the reduced diameter section of the pin and the locking seat. This prevents the induction coil from interfering with the hook plate, ensuring smooth unlocking and locking operations.

[0015] In the aforementioned machine tool skylight structure, a protective plate in the shape of a "U" with its middle section protruding forward is fixed to the front end face of the movable seat. The rear end face of the protective cover can abut against the middle section of the protective plate, and the hook plate is fixedly connected to the protective plate. This movable seat is a Y-axis movable seat that moves back and forth. The X-axis and Z-axis movable seats are located inside the protective plate. Thus, when the protective cover moves backward and extends, the protective cover and the protective plate abut against each other, closing the skylight to reduce oil mist diffusion from the top. At the same time, the protective cover abuts against the protective plate, and the hook plate is fixedly connected to the protective plate, separating the protective cover and the hook plate from the X-axis and Z-axis movable seats. This ensures that the protective cover and the hook plate do not affect the movement of the X-axis and Z-axis movable seats, which is beneficial for ensuring normal machine tool processing.

[0016] In the above-described machine tool skylight structure, an L-shaped mounting plate is fixedly connected to the protective plate, and the hook plate is fixedly connected to the mounting plate. Fixing the hook plate with the mounting plate facilitates adjustment of the hook plate's position, ensuring the hook plate's opening is accurately aligned with the pin, allowing the skylight to open and close smoothly.

[0017] In the aforementioned machine tool skylight structure, locking seats are provided on both sides of the protective cover, and each locking seat contains a pin. Two hook plates are correspondingly provided on the movable seat, and two positioning seats are correspondingly provided on the machine tool. This allows for locking and unlocking of both sides of the protective cover, ensuring stable connection when the cover is connected to the movable seat and stable fixation when the cover is fixed to the positioning seats. This facilitates smooth opening and closing of the skylight, making it convenient for loading and unloading materials from the top of the machine tool while ensuring normal processing.

[0018] Compared with the prior art, the present invention has the following advantages: 1. Through the cooperation of the locking seat, pin, hook plate, and positioning seat, the protective cover can lock with the positioning seat and unlock with the moving seat when the front end of the machine tool retracts, opening the skylight to facilitate loading and unloading by the gantry robot. When the protective cover extends, it can unlock with the positioning seat and lock with the moving seat. When the skylight closes, the protective cover and the moving seat move synchronously to ensure normal machine tool processing. Moreover, a single pin can achieve locking and unlocking at two points, making the structure simple and easy to operate.

[0019] 2. The pin is inserted into the locking seat, the cylinder is fixed to the locking seat, and the piston rod of the cylinder is inserted into the locking seat and fixed to the pin, making the structure compact and the pin work stably.

[0020] 3. A protective plate is installed on the moving seat. The rear end face of the cover can be close to the protective plate. The hook plate is fixedly connected to the protective plate to avoid interference and enable the machine tool to process normally. Attached Figure Description

[0021] Figure 1 This is a three-dimensional view of the skylight structure installed on the machine tool with the protective cover extended.

[0022] Figure 2 yes Figure 1 Enlarged view of point A in the middle.

[0023] Figure 3 yes Figure 1 Enlarged view of point B in the middle.

[0024] Figure 4 This is a three-dimensional view of the latch point when the skylight structure cover is retracted.

[0025] Figure 5 yes Figure 4 Side view.

[0026] Figure 6 yes Figure 5 A cross-sectional view along the CC direction.

[0027] Figure 7 yes Figure 6 A cross-sectional view along the DD direction.

[0028] Figure 8This is a three-dimensional view of the skylight structure cover after it has retracted, showing the pin separating from the hook plate.

[0029] Figure 9 This is a three-dimensional view of the sunroof structure when the movable seat moves forward and the pin is aligned with the positioning seat.

[0030] Figure 10 yes Figure 9 Enlarged view of point E in the middle.

[0031] In the diagram, 1. Frame; 2. Moving seat; 3. Protective cover; 4. Locking seat; 5. Pin; 5a. Reduced diameter section; 5b. Spherical head; 6. Protective plate; 7. Hook plate; 7a. Insertion part; 7b. Opening; 8. Cylinder; 9. Sliding bearing; 10. Positioning seat; 10a. Spherical surface; 11. Front support; 12. Rear support; 13. Air pipe; 14. Connecting frame; 15. Gasket; 16. Connecting plate; 17. Position sensor; 18. Induction coil; 19. Mounting plate. Detailed Implementation

[0032] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0033] Example 1

[0034] like Figure 1 , Figure 2 and Figure 3 As shown, a machine tool skylight structure includes a retractable cover 3 mounted on the top of the machine tool, such as an accordion-style cover 3 or a steel telescopic guide rail cover 3 composed of multiple overlapping steel plates. Locking seats 4 are fixed to both sides of the rear end of the cover 3, and vertically movable pins 5 are inserted into the locking seats 4. The rear end of the cover 3 is fixed to the locking seats 4 via an intermediate plate [not shown in the figure]. A vertical five-axis machine tool includes a frame 1, with a window at the top. The cover 3 is positioned at the window and can cover the window when extended. A movable seat 2 is slidably connected to the top of the frame 1, and the front end of the cover 3 is fixedly connected to the front end of the frame 1. A protective plate 6, shaped like a "U" and protruding forward in the middle, is fixed to the front end face of the movable seat 2. The rear end face of the cover 3 can abut against the middle section of the protective plate 6. This movable seat 2 is a Y-axis movable seat that moves back and forth; the X-axis and Z-axis movable seats [not shown in the figure] are located within the protective plate 6. Hook plates 7 are fixedly connected to both sides of the protective plate 6 and the protective cover 3, respectively. The hook plates 7 are respectively arranged to correspond with the pins 5, and the hook plates 7 have a mating part 7a for the pins 5 to be inserted. An L-shaped mounting plate 19 is fixedly connected to the protective plate 6, and the hook plates 7 are fixedly connected to the mounting plate 19. There are also two positioning seats 10 for the pins 5 to be inserted at the front end of the frame 1. The positioning seats 10 are located on both sides of the protective cover 3, and the positioning seats 10 are respectively arranged to correspond with the pins 5.

[0035] like Figure 4 , Figure 5 and Figure 6 As shown, the pin 5 is a round rod with a reduced diameter in the middle, and the mating part 7a of the hook plate 7 is C-shaped with its opening 7b facing forward. When the lower end of the pin 5 is inserted into the positioning seat 10, the mating part 7a is opposite to the reduced diameter section 5a of the pin 5, and the reduced diameter section 5a of the pin 5 can pass through the opening 7b of the mating part 7a. Figure 7 As shown, the diameter of the inner hole of the fitting part 7a is equal to or slightly larger than the outer diameter of the pin 5; the width of the opening 7b of the fitting part 7a is smaller than the outer diameter of the pin 5, and the width of the opening 7b of the fitting part 7a is equal to or slightly larger than the diameter of the reduced diameter section 5a of the pin 5; the axial length of the reduced diameter section 5a of the pin 5 is greater than the axial thickness of the fitting part 7a. A cylinder 8 is fixed on the top surface of the locking seat 4, and the piston rod of the cylinder 8 is inserted into the locking seat 4 and fixedly connected to the upper end of the pin 5. A sliding bearing 9 is fixed in the locking seat 4, and the upper end of the pin 5 is inserted into the sliding bearing 9. A spherical surface 10a is provided on the inner wall of the positioning seat 10, and the lower end of the pin 5 has a spherical head 5b. When the lower end of the pin 5 is inserted into the inner hole of the positioning seat 10, the spherical head 5b abuts against the spherical surface 10a. The spherical head 5b can be a semi-circular head or a flat round head.

[0036] like Figure 1 and Figure 2 As shown, a front bracket 11 is also fixedly connected to the locking seat 4, and a rear bracket 12 is fixedly connected to the protective plate 6. The air pipe 13 of the cylinder 8 is fixed to the front bracket 11 and the rear bracket 12. Figure 1 and Figure 3 As shown, a connecting frame 14 is fixed to the front end of the frame 1, and a positioning seat 10 is fixedly connected to the connecting frame 14. A shim 15 is provided between the positioning seat 10 and the connecting frame 14, and the height of the positioning seat 10 can be adjusted by installing shims 15 of different thicknesses. Figure 4 and Figure 5 As shown, a connecting plate 16 is also fixedly connected to the locking seat 4. Two position sensors 17 arranged along the axial direction of the pin 5 are fixedly connected to the connecting plate 16. An induction coil 18 that can be sensed by the position sensors 17 is fixedly connected to the pin 5. The induction coil 18 is located between the reduced diameter section 5a of the pin 5 and the locking seat 4.

[0037] like Figure 1 and Figure 2As shown, when the machine tool is processing a workpiece, the skylight is closed, the protective cover 3 is in an extended state, and the rear end face of the protective cover 3 is against the protective plate 6. The pin 5 is inserted into the fitting part 7a, and the reduced diameter section 5a of the pin 5 is offset from the fitting part 7a. Since the width of the opening 7b of the fitting part 7a is smaller than the outer diameter of the pin 5, the pin 5 will not come out of the opening 7b of the fitting part 7a. The pin 5 cooperates with the hook plate 7 to fix the rear end of the protective cover 3 to the moving base 2. The rear end of the protective cover 3 can move synchronously with the moving base 2, allowing the machine tool to process normally. Figure 9 and Figure 10 As shown, when the workpiece needs to be loaded or unloaded after processing, the moving seat 2 moves forward, pushing the protective cover 3 to retract forward. The locking seat 4 and the pin 5 move forward with the protective cover 3. When the pin 5 is opposite to the positioning seat 10, as shown... Figure 4 As shown, cylinder 8 drives pin 5 to move downward, causing the lower end of pin 5 to insert into positioning seat 10. At this time, the mating part 7a is opposite to the reduced diameter section 5a of pin 5. Then, as... Figure 8 As shown, when the movable seat 2 moves backward, the reduced diameter section 5a of the pin 5 disengages from the hook plate 7 through the opening 7b of the fitting part 7a. The movable seat 2 will not pull the protective cover 3 backward, and the pin 5, inserted into the positioning seat 10 and the locking seat 4, keeps the protective cover 3 locked, preventing it from moving backward. After the movable seat 2 moves backward to avoid the space above the workbench, the gantry robot can load and unload materials normally, and the protective cover 3 does not gather at the rear with the movable seat 2 to cause interference, making loading and unloading convenient. After loading and unloading are completed, as... Figure 4 As shown, the movable seat 2 moves forward, and the reduced diameter section 5a of the pin 5 passes through the opening 7b of the fitting part 7a, allowing the pin 5 to enter the hook plate 7, and then... Figure 9 As shown, cylinder 8 drives pin 5 to move upward, causing pin 5 to disengage from positioning seat 10. At this time, the reduced diameter section 5a of pin 5 is misaligned with the mating part 7a, and pin 5 will not come out of the opening 7b of mating part 7a. Pin 5 cooperates with hook plate 7 to fix the rear end of cover 3 to moving seat 2, as shown. Figure 1 and Figure 2 As shown, the movable seat 2 moves backward, causing the protective cover 3 to extend and close the skylight. Therefore, this skylight structure allows the machine tool to easily load and unload materials from the top while ensuring normal processing. Moreover, a single pin 5 can achieve locking and unlocking at two points, making the structure simple and easy to operate.

[0038] Example 2

[0039] The drive source for pin 5 is a linear motor. A relay is installed between the linear motor and the power supply. The machine tool controller is connected to the relay to control the switching of the linear motor. The linear motor's wires are fixed to the front bracket 11 and the rear bracket 12. Other structures are the same as in Embodiment 1.

[0040] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A machine tool skylight structure, comprising a retractable cover (3) mounted on the top of the machine tool, wherein the top of the machine tool is provided with a movable seat (2) that can move back and forth, characterized in that, The front end of the shield (3) is fixed on the machine tool, the rear end of the shield (3) is fixed with a locking seat (4), a movable bolt (5) is inserted on the locking seat (4), the bolt (5) is in the shape of a round rod with a reduced diameter at the middle section, a hook plate (7) is fixed on the movable seat (2), the hook plate (7) has a mating portion (7a) for the bolt (5) to insert into, the mating portion (7a) is C-shaped with an opening (7b) facing forward, the width of the opening (7b) of the mating portion (7a) is smaller than the outer diameter of the bolt (5), the front end of the machine tool is further fixed with a positioning seat (10) for the bolt (5) to insert into. When the bolt (5) is inserted into the positioning seat (10), the mating portion (7a) is opposite to the reduced diameter section (5a) of the bolt (5), and the reduced diameter section (5a) of the bolt (5) can pass through the opening (7b) of the mating portion (7a). When the shield (3) is retracted at the front end of the machine tool, it is locked with the positioning seat (10) and unlocked from the movable seat (2); when the shield (3) is extended, it is unlocked from the positioning seat (10) and locked with the movable seat (2) to move synchronously with the movable seat (2).

2. The machine tool skylight structure according to claim 1, characterized in that, The axial length of the reduced diameter section (5a) of the bolt (5) is greater than the axial thickness of the mating portion (7a), and the width of the opening (7b) of the mating portion (7a) is greater than the diameter of the reduced diameter section (5a) of the bolt (5).

3. The machine tool skylight structure according to claim 1, characterized in that, An air cylinder (8) is fixed on the locking seat (4), and the piston rod of the air cylinder (8) is inserted into the locking seat (4) and fixedly connected with the bolt (5).

4. The machine tool skylight structure according to claim 1, characterized in that, A sliding bearing (9) is fixed in the locking seat (4), and the bolt (5) is inserted into the sliding bearing (9).

5. The machine tool skylight structure according to claim 1, characterized in that, A spherical surface (10a) is provided on the positioning seat (10), the lower end of the bolt (5) has a spherical head (5b), and when the lower end of the bolt (5) is inserted into the positioning seat (10), the spherical head (5b) abuts against the spherical surface (10a).

6. A machine tool skylight structure according to any one of claims 1-5, characterized in that, A connecting plate (16) is further fixedly connected to the locking seat (4), two position sensors (17) arranged along the axial direction of the bolt (5) are fixed on the connecting plate (16), and a sensing coil (18) that can be sensed by the position sensors (17) is fixedly connected to the bolt (5).

7. A machine tool skylight structure according to claim 6, characterized in that, The sensing coil (18) is located between the reduced diameter section (5a) of the bolt (5) and the locking seat (4).

8. A machine tool skylight structure according to any one of claims 1-5, characterized in that, A protective plate (6) which is in a "U" shape with the middle section protruding forward is fixed on the front end face of the movable seat (2), the rear end face of the shield (3) can abut against the middle section of the protective plate (6), and the hook plate (7) is fixedly connected with the protective plate (6).

9. A machine tool skylight structure according to claim 8, characterized in that, An L-shaped mounting plate (19) is fixedly connected to the protective plate (6), and the hook plate (7) is fixedly connected to the mounting plate (19).

10. A machine tool skylight structure according to any one of claims 1-5, characterized in that, Locking seats (4) are provided on both sides of the shield (3), and each locking seat (4) is provided with the bolt (5), two hook plates (7) are correspondingly provided on the movable seat (2), and two positioning seats (10) are correspondingly provided on the machine tool.

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