An automatically controllable argon gas input device for NdFeB processing

Abstract

The present invention relates to the field of NdFeB sintering, and in particular to an automatically controllable argon gas inlet for NdFeB processing. Technical problem: Provide an automatically controllable argon gas inlet for NdFeB processing. The technical implementation scheme of the present invention is: an automatically controllable argon gas inlet for NdFeB processing, comprising a vacuum melting furnace, a bracket and an argon gas tank, etc. The upper right part of the bracket is connected to the vacuum melting furnace, and the upper left part of the bracket is connected to the argon gas tank. The present invention detects that the temperature in the vacuum melting furnace reaches the set temperature through a thermal sensor, and automatically turns on the first motor so that the valve automatically opens. There is no need to manually open the valve. The first rotating rod rotates, and under the action of the transmission wheel and the belt, the threaded rod rotates to drive the hollow block to move, so that the amount of argon gas filled into the vacuum melting furnace can be controlled through the hollow block. In this way, the accurate amount of argon gas filled into the vacuum melting furnace can be automatically controlled.

Description

Technical Field

[0001] The invention relates to the field of NdFeB sintering, in particular to an automatically controllable argon gas input device for NdFeB processing. Background Art

[0002] During the sintering process of NdFeB, one of the steps is vacuum melting. During the vacuum melting process, argon needs to be filled in the vacuum melting furnace as a protective gas. Argon is a rare gas. When filling argon, the argon tank is generally opened through a valve, and the argon then enters the vacuum melting furnace through a pipe.

[0003] Patent publication number CN217030781U discloses an argon input device for the production of rapidly quenched NdFeB magnetic powder, including an argon tank and a support frame supporting the argon tank. The top of the argon tank is connected to an outlet pipe, and a valve is provided on the top of the outlet pipe. One side of the outlet pipe is connected to one end of an air guide pipe, and the other end of the air guide pipe is connected to an input pipe through a joint. A sealing plate is provided on the air guide pipe, and the bottom of the sealing plate is connected to a receiving plate. The bottom of the receiving plate is connected to the support frame through a support assembly, and an adjustment plate is provided on the top of the sealing plate for sliding.

[0004] The argon gas input device for the production of rapid-quenching NdFeB magnetic powder is used to fill the vacuum melting furnace with argon gas. First, the input pipe and the vacuum melting furnace are connected, and then the valve is unscrewed to allow the argon gas to enter the vacuum melting furnace through the outlet pipe, the gas guide pipe, the joint and the input pipe in sequence. The lifting plate can be moved by rotating the threaded rod to adjust the position of the regulating plate and control the amount of argon gas outflow. However, because the above-mentioned valve and threaded rod need to be manually operated and rotated, they are inconvenient to use. Now, an automatically controllable argon gas input device for NdFeB processing is developed. Summary of the Invention

[0005] In order to overcome the disadvantage that the existing argon gas input device for the production of rapid quenching NdFeB magnetic powder requires manual operation and is therefore inconvenient to use, the technical problem is to provide an automatically controllable argon gas input device for NdFeB processing.

[0006] The technical implementation plan of the present invention is: an automatically controllable argon inlet device for NdFeB processing, including a vacuum melting furnace, a bracket, an argon tank, a valve, a slide rail, an opening mechanism and a quantitative mechanism. The upper right part of the bracket is connected to the vacuum melting furnace, the upper left part of the bracket is connected to the argon tank, the upper left part of the vacuum melting furnace is connected to the slide rail, the left and right sides of the slide rail are connected to gas pipes, the left part of the left gas pipe is connected to the argon tank, and the right part of the right gas pipe is connected to the vacuum melting furnace. The upper part of the argon tank is rotatably connected to the valve, the upper part of the argon tank is provided with an opening mechanism, and the slide rail is provided with a quantitative mechanism.

[0007] As a further preferred solution, the opening mechanism includes a thermal sensor, a first motor, a first rotating rod and a fixed rod. The thermal sensor is connected to the upper left inner part of the vacuum melting furnace, and the fixed rods are connected to the front and rear sides of the upper part of the argon tank. The first motor is connected between the upper parts of the fixed rods, and the first motor and the thermal sensor are electrically connected. The lower part of the first motor output shaft is connected to the first rotating rod, and the lower part of the first rotating rod is connected to the valve.

[0008] As a further preferred solution, the quantitative mechanism includes a hollow block, a transmission wheel, a belt, a threaded rod and a first fixed block. The hollow block is slidably connected to the slide rail, a notch is opened in the middle of the hollow block, the rear lower part of the slide rail is connected to the first fixed block, the first fixed block is rotatably connected to the threaded rod, the threaded rod and the hollow block are threadedly connected, the upper part of the threaded rod is connected to the transmission wheel, the upper part of the first rotating rod is connected to the transmission wheel, and a belt is wound between the two transmission wheels.

[0009] As a further preferred solution, it also includes an adjustment mechanism for adjusting the size of the notch area on the hollow block, the adjustment mechanism includes a bidirectional screw, a slider and a U-shaped block, the bidirectional screw is rotatably connected between the upper and lower sides of the hollow block, the upper and lower sides of the bidirectional screw are threadedly connected to the slider, the sliders are slidably connected to the hollow block, the lower part of the hollow block is connected to the U-shaped block, and the U-shaped block is rotatably connected to the lower part of the bidirectional screw.

[0010] As a further preferred solution, it also includes a circulation mechanism for quickly and evenly distributing argon in the vacuum melting furnace. The circulation mechanism includes a second fixed block, blades, a second rotating rod and a second motor. Two second fixed blocks are connected to the upper left inner part of the vacuum melting furnace, and the two second fixed blocks are respectively located on the front and rear sides of the gas pipe on the right side. A second rotating rod is rotatably connected between the two second fixed blocks, and the rear part of the second rotating rod extends out of the vacuum melting furnace. The second rotating rod and the vacuum melting furnace are rotatably connected. Blades are connected to the second rotating rod, and the blades are located between the two second fixed blocks. The rear part of the vacuum melting furnace is connected to the second motor, and the front part of the second motor output shaft is connected to the rear part of the second rotating rod.

[0011] As a further preferred solution, it also includes a cooling mechanism for cooling the argon gas tank. The cooling mechanism includes a water-cooling device and a support frame. The upper left part of the bracket is connected to the support frame, and the support frame is arranged on the outside of the argon gas tank. The middle part of the support frame is ringed with a water-cooling device.

[0012] As a further preferred solution, an exhaust mechanism for blowing away argon is also included, and the exhaust mechanism includes a rodless cylinder and a fan. A rodless cylinder is provided on the left side of the vacuum melting furnace, and a fan is slidably connected to the rodless cylinder.

[0013] As a further preferred solution, the hollow block is made of rubber.

[0014] The beneficial effects of the present invention are as follows: 1. The present invention detects through a thermal sensor that the temperature in the vacuum melting furnace reaches a set temperature, and automatically starts the first motor so that the valve is automatically opened without the need to manually open the valve. By rotating the first rotating rod, the threaded rod rotates under the action of the transmission wheel and the belt to drive the hollow block to move, so that the hollow block can control the amount of argon gas filled into the vacuum melting furnace. In this way, the accurate amount of argon gas filled into the vacuum melting furnace can be automatically controlled.

[0015] 2. The present invention rotates the bidirectional screw to move the slider, thereby changing the size of the notch on the hollow block, thereby adjusting the total amount of argon gas filled into the vacuum melting furnace.

[0016] 3. The present invention accelerates the speed of uniform argon distribution by adjusting the rotating blades, thereby making the protective effect of argon better and facilitating the smelting work.

[0017] 4. Cool the argon tank with a water cooling device to prevent the argon tank from cracking and exploding due to heat conduction.

[0018] 5. The fan is driven up and down by a rodless cylinder to prevent the argon gas near the quantitative mechanism from being blown away, so as to avoid the argon gas concentration near the quantitative mechanism being too high and affecting the personal safety of the operator. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0020] Figure 2 It is a partial three-dimensional structural schematic diagram of the present invention.

[0021] Figure 3 It is a schematic diagram of the three-dimensional structure of the opening mechanism of the present invention.

[0022] Figure 4 It is a first three-dimensional structural schematic diagram of the quantitative mechanism of the present invention.

[0023] Figure 5 This is a second three-dimensional structural diagram of the quantitative mechanism of the present invention.

[0024] Figure 6 It is a schematic diagram of the three-dimensional structure of the adjustment mechanism of the present invention.

[0025] Figure 7 It is a first three-dimensional structural schematic diagram of the circulation mechanism of the present invention.

[0026] Figure 8 This is a second three-dimensional structural diagram of the circulation mechanism of the present invention.

[0027] Figure 9 It is a schematic diagram of the three-dimensional structure of the cooling mechanism of the present invention.

[0028] Figure 10 It is a schematic diagram of the three-dimensional structure of the exhaust mechanism of the present invention.

[0029] Names and serial numbers of parts in the figure: 1- vacuum melting furnace, 2- bracket, 3- argon tank, 4- valve, 5- slide rail, 6- opening mechanism, 61- thermal sensor, 62- first motor, 63- first rotating rod, 64- fixed rod, 7- quantitative mechanism, 71- hollow block, 72- transmission wheel, 73- belt, 74- threaded rod, 75- first fixed block, 8- adjusting mechanism, 81- bidirectional screw, 82- slider, 83- U-shaped block, 9- circulation mechanism, 91- second fixed block, 92- blade, 93- second rotating rod, 94- second motor, 10- cooling mechanism, 101- water cooling device, 102- support frame, 11- exhaust mechanism, 111- rodless cylinder, 112- fan. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0031] Example 1

[0032] An automatically controllable argon gas feeder for NdFeB machining, such as Figure 1 and Figure 2 As shown, it includes a vacuum melting furnace 1, a bracket 2, an argon tank 3, a valve 4, a slide rail 5, an opening mechanism 6 and a quantitative mechanism 7. The upper right part of the bracket 2 is connected to the vacuum melting furnace 1, the upper left part of the bracket 2 is connected to the argon tank 3, the upper left part of the vacuum melting furnace 1 is connected to the slide rail 5, and the left and right sides of the slide rail 5 are connected to gas pipes. The left part of the left gas pipe is connected to the argon tank 3, and the right part of the right gas pipe is connected to the vacuum melting furnace 1. The upper part of the argon tank 3 is rotatably connected to the valve 4. The upper part of the argon tank 3 is provided with an opening mechanism 6, which is used to automatically open the valve 4. The slide rail 5 is provided with a quantitative mechanism 7, which is used to control the amount of argon gas introduced into the vacuum melting furnace 1 to be a fixed amount.

[0033] like Figure 1 and Figure 3 As shown, the opening mechanism 6 includes a thermal sensor 61, a first motor 62, a first rotating rod 63 and a fixed rod 64. The thermal sensor 61 is connected to the upper left inner part of the vacuum melting furnace 1, and the fixed rods 64 are connected to the front and rear sides of the upper part of the argon tank 3. The first motor 62 is connected between the upper parts of the fixed rods 64. The first motor 62 and the thermal sensor 61 are electrically connected. The first motor 62 is automatically started through the thermal sensor 61. The lower part of the output shaft of the first motor 62 is connected to the first rotating rod 63, and the lower part of the first rotating rod 63 is connected to the valve 4.

[0034] like Figure 1 、 Figure 4 and Figure 5 As shown, the quantitative mechanism 7 includes a hollow block 71, a transmission wheel 72, a belt 73, a threaded rod 74 and a first fixed block 75. The hollow block 71 is slidably connected to the slide rail 5. The hollow block 71 is made of rubber and has a notch in the middle. The rear lower part of the slide rail 5 is connected to the first fixed block 75. The threaded rod 74 is rotatably connected to the first fixed block 75. The threaded rod 74 and the hollow block 71 are threadedly connected. The upper part of the threaded rod 74 is connected to the transmission wheel 72. The upper part of the first rotating rod 63 is connected to the transmission wheel 72. A belt 73 is wound between the two transmission wheels 72. The first rotating rod 63 rotates, so that under the action of the transmission wheel 72 and the belt 73, the threaded rod 74 rotates to drive the hollow block 71 to move, so that the hollow block 71 can control the amount of argon gas filled into the vacuum melting furnace 1.

[0035] Use the automatically controllable argon gas inlet for NdFeB processing to input argon gas, start the thermal sensor 61 first, when the material is poured into the vacuum melting furnace 1, the vacuum melting furnace 1 will first perform vacuum work, and then perform oxygen extraction and heating. At this time, the temperature in the vacuum melting furnace 1 will rise. When the temperature rises to a certain value, it means that the oxygen extraction work is completed. At this time, the thermal sensor 61 senses that the temperature has reached the set temperature, and the thermal sensor 61 therefore starts the first motor 62. The output shaft of the first motor 62 drives the first rotating rod 63 to rotate, thereby causing the valve 4 to rotate. When the first rotating rod 63 rotates, the first rotating rod 63 drives the valve 4 to rotate. The transmission wheel 72 of the belt 73 rotates, and the transmission wheel 72 on the upper part of the threaded rod 74 rotates under the action of the belt 73, thereby rotating the threaded rod 74, and the threaded rod 74 drives the hollow block 71 to move downward. Because the initial state is that the lower part of the hollow block 71 blocks the gas pipe, and the hollow block 71 is made of rubber, it can prevent argon from leaking from the gap, and the gap of the hollow block 71 is located at the upper part of the gas pipe. When the hollow block 71 moves downward, the gap moves downward, so that the argon in the gas pipe can be input into the vacuum melting furnace 1 through the gap. As the hollow block 71 moves downward, the gap passes through the gas pipe, and the gas pipe is now empty. The upper part of the core block 71 is blocked, and argon is no longer filled into the vacuum melting furnace 1. At this time, the argon has been partially filled, causing the temperature in the vacuum melting furnace 1 to rise, thereby causing all the materials to melt. At this time, once the heat sensor 61 detects that the temperature exceeds the set value, it will control the output shaft of the first motor 62 to rotate in the opposite direction, so that under the drive of the first rotating rod 63, the valve 4 is closed. In this process, the first rotating rod 63 drives the adjacent transmission wheel 72 to rotate in the opposite direction, so that under the action of the belt 73 and the other transmission wheel 72, the threaded rod 74 rotates in the opposite direction, causing the hollow block 71 to move upward and reset. When the gap moves to the gas pipe, the argon The argon is filled into the vacuum melting furnace 1 again. When the hollow block 71 is reset, the argon is just filled. The thermal sensor 61 is turned off. The thermal sensor 61 detects that the temperature in the vacuum melting furnace 1 reaches the set temperature, and the first motor 62 is automatically turned on, so that the valve 4 is automatically opened. There is no need to manually open the valve 4. The first rotating rod 63 rotates, and under the action of the transmission wheel 72 and the belt 73, the threaded rod 74 rotates to drive the hollow block 71 to move, so that the hollow block 71 can control the amount of argon filled into the vacuum melting furnace 1. In this way, the accurate amount of argon filled into the vacuum melting furnace 1 can be automatically controlled.

[0036] Example 2

[0037] On the basis of Example 1, Figure 1 and Figure 6As shown, it also includes an adjustment mechanism 8, which includes a bidirectional screw 81, a slider 82 and a U-shaped block 83. The bidirectional screw 81 is rotatably connected between the upper and lower sides of the interior of the hollow block 71, and the upper and lower sides of the bidirectional screw 81 are threadedly connected with sliders 82. The sliders 82 are used to adjust the area of the notch on the hollow block 71. The sliders 82 are slidably connected to the hollow block 71. The lower part of the hollow block 71 is connected to the U-shaped block 83, and the U-shaped block 83 is rotatably connected to the lower part of the bidirectional screw 81.

[0038] like Figure 2 、 Figure 7 and Figure 8 As shown, a circulation mechanism 9 is also included, and the circulation mechanism 9 includes a second fixed block 91, a blade 92, a second rotating rod 93 and a second motor 94. Two second fixed blocks 91 are connected to the upper left inner part of the vacuum melting furnace 1, and the two second fixed blocks 91 are respectively located on the front and rear sides of the gas pipe on the right side. A second rotating rod 93 is rotatably connected between the two second fixed blocks 91, and the rear part of the second rotating rod 93 extends out of the vacuum melting furnace 1. The second rotating rod 93 and the vacuum melting furnace 1 are rotatably connected. A blade 92 is connected to the second rotating rod 93. The blade 92 is used to speed up the uniform distribution of argon in the vacuum melting furnace 1, and the blade 92 is located between the two second fixed blocks 91. The rear part of the vacuum melting furnace 1 is connected to the second motor 94, and the front part of the output shaft of the second motor 94 is connected to the rear part of the second rotating rod 93.

[0039] like Figure 1 and Figure 9 As shown, a cooling mechanism 10 is also included. The cooling mechanism 10 includes a water-cooling device 101 and a support frame 102. The upper left part of the bracket 2 is connected to the support frame 102, and the support frame 102 is sleeved on the outside of the argon tank 3. The middle part of the support frame 102 is ringed with a water-cooling device 101, and the water-cooling device 101 is used to cool the argon tank 3.

[0040] like Figure 1 and Figure 10 As shown, an exhaust mechanism 11 is also included. The exhaust mechanism 11 includes a rodless cylinder 111 and a fan 112. The rodless cylinder 111 is provided on the left side of the vacuum melting furnace 1. The fan 112 is slidingly connected to the rodless cylinder 111. The fan 112 is used to blow away the argon gas near the quantitative mechanism 7.

[0041] People can further control the amount of argon gas filled in by adjusting the size of the notch area on the hollow block 71. By rotating the bidirectional screw 81, the slider 82 moves toward the side in the direction of approaching each other under the drive of the bidirectional screw 81, thereby reducing the area of the notch. At this time, the total amount of argon gas that can be filled into the vacuum melting furnace 1 through the notch is reduced. In order to increase the total amount of argon gas filled into the vacuum melting furnace 1 again, the bidirectional screw 81 is rotated in the opposite direction to move the slider 82 toward the side in the direction of moving away from each other, so that the area of the notch is increased. At this time, the total amount of argon gas that can be filled into the vacuum melting furnace 1 through the notch is increased. By rotating the bidirectional screw 81, the slider 82 moves, thereby changing the size of the notch area on the hollow block 71. In this way, the total amount of argon gas filled into the vacuum melting furnace 1 can be adjusted.

[0042] In order to quickly and evenly distribute the argon in the vacuum melting furnace 1, after the argon is filled, the second motor 94 is started. Under the action of the output shaft of the second motor 94, the second rotating rod 93 rotates. Driven by the second rotating rod 93, the blade 92 rotates, thereby causing the air in the vacuum melting furnace 1 to flow. After the blade 92 rotates for thirty seconds, the second motor 94 is turned off. By rotating the blade 92, the speed of uniform distribution of the argon is accelerated, thereby making the protective effect of the argon better, which is beneficial to the melting work.

[0043] Because when argon encounters high heat, the internal pressure of the container increases, and there is a risk of cracking and explosion, so the water cooling device 101 is started to cool the argon tank 3. When the smelting work is completed, the water cooling device 101 is turned off, and the argon tank 3 is cooled by the water cooling device to prevent the argon tank 3 from cracking and exploding due to the increase in temperature due to heat conduction.

[0044] In order to prevent the argon concentration near the quantitative mechanism 7 from being too high and affecting the personal safety of the operator, the rodless cylinder 111 is started, and the fan 112 is started. The rodless cylinder 111 drives the fan 112 to move up and down. When the argon is filled, the rodless cylinder 111 is closed, and the fan 112 is turned off. The fan 112 is driven up and down by the rodless cylinder 111 to prevent the argon near the quantitative mechanism 7 from being blown away, thereby avoiding the argon concentration near the quantitative mechanism 7 being too high and affecting the personal safety of the operator.

[0045] The above embodiments are provided to persons familiar with the art for implementing or using the present invention. Personnel familiar with the art may make various modifications or changes to the above embodiments without departing from the inventive concept of the present invention. Therefore, the scope of protection of the present invention is not limited to the above embodiments, but should be the maximum scope of the innovative features mentioned in the claims.

Claims

1. An automatically controllable argon gas input device for NdFeB processing, comprising a vacuum melting furnace (1), a bracket (2), an argon gas tank (3), a valve (4) and a slide rail (5), wherein the upper right portion of the bracket (2) is connected to the vacuum melting furnace (1), the upper left portion of the bracket (2) is connected to the argon gas tank (3), the upper left portion of the vacuum melting furnace (1) is connected to the slide rail (5), the left and right sides of the slide rail (5) are connected to gas pipes, the left portion of the left gas pipe is connected to the argon gas tank (3), the right portion of the right gas pipe is connected to the vacuum melting furnace (1), and the upper portion of the argon gas tank (3) is rotatably connected to the valve (4), wherein: It also includes an opening mechanism (6) and a quantitative mechanism (7). The upper part of the argon tank (3) is provided with the opening mechanism (6), and the slide rail (5) is provided with the quantitative mechanism (7). The opening mechanism (6) includes a thermal sensor (61), a first motor (62), a first rotating rod (63) and a fixed rod (64). The upper left part of the vacuum melting furnace (1) is connected to the thermal sensor (61). The upper front and rear sides of the upper part of the argon tank (3) are connected to the fixed rod (64). The upper part of the fixed rod (64) is connected to the first motor (62). The first motor (62) and the thermal sensor (61) are electrically connected. The lower part of the output shaft of the first motor (62) is connected to the first rotating rod (63). The lower part of the first rotating rod (63) is connected to the valve (4). The quantitative mechanism (7) includes a hollow block ( 71), a transmission wheel (72), a belt (73), a threaded rod (74) and a first fixed block (75); a hollow block (71) is slidably connected to the slide rail (5); a notch is opened in the middle of the hollow block (71); a first fixed block (75) is connected to the rear lower part of the slide rail (5); a threaded rod (74) is rotatably connected to the first fixed block (75); the threaded rod (74) and the hollow block (71) are threadedly connected; the upper part of the threaded rod (74) is connected to the transmission wheel (72); the upper part of the first rotating rod (63) is connected to the transmission wheel (72); a belt (73) is wound between the two transmission wheels (72).

2. The automatically controllable argon gas inlet device for NdFeB processing according to claim 1, characterized in that: The hollow block (71) further comprises an adjusting mechanism (8) for adjusting the size of the notch area. The adjusting mechanism (8) comprises a bidirectional screw (81), a slider (82) and a U-shaped block (83). The bidirectional screw (81) is rotatably connected between the upper and lower sides of the hollow block (71). The upper and lower sides of the bidirectional screw (81) are both threadedly connected to the slider (82). The slider (82) is slidably connected to the hollow block (71). The lower part of the hollow block (71) is connected to the U-shaped block (83). The U-shaped block (83) is rotatably connected to the lower part of the bidirectional screw (81).

3. The automatically controllable argon gas inlet device for NdFeB processing according to claim 2, characterized in that: The invention also includes a circulation mechanism (9) for quickly and evenly distributing argon in the vacuum melting furnace (1). The circulation mechanism (9) includes a second fixed block (91), a blade (92), a second rotating rod (93) and a second motor (94). Two second fixed blocks (91) are connected to the upper left portion of the vacuum melting furnace (1), and the two second fixed blocks (91) are respectively located on the front and rear sides of the gas transmission pipe on the right side. A second rotating rod (93) is rotatably connected between the two second fixed blocks (91), and the rear part of the second rotating rod (93) extends out of the vacuum melting furnace (1). The second rotating rod (93) and the vacuum melting furnace (1) are rotatably connected. The second rotating rod (93) is connected to the blade (92), and the blade (92) is located between the two second fixed blocks (91). The rear part of the vacuum melting furnace (1) is connected to the second motor (94), and the front part of the output shaft of the second motor (94) is connected to the rear part of the second rotating rod (93).

4. The automatically controllable argon gas inlet device for NdFeB processing according to claim 3, characterized in that: The apparatus further comprises a cooling mechanism (10) for cooling the argon gas tank (3). The cooling mechanism (10) comprises a water-cooling device (101) and a support frame (102). The upper left portion of the bracket (2) is connected to the support frame (102), and the support frame (102) is sleeved on the outside of the argon gas tank (3). The middle portion of the support frame (102) is provided with a water-cooling device (101).

5. The automatically controllable argon gas inlet device for NdFeB processing according to claim 4, characterized in that: The vacuum melting furnace (1) further comprises an exhaust mechanism (11) for blowing away argon gas. The exhaust mechanism (11) comprises a rodless cylinder (111) and a fan (112). The rodless cylinder (111) is provided on the left side of the vacuum melting furnace (1), and the fan (112) is slidably connected to the rodless cylinder (111).

6. The automatically controllable argon gas inlet device for NdFeB processing according to claim 5, characterized in that: The hollow block (71) is made of rubber.

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