Heat-insulating solid wood composite floor and its processing equipment

Abstract

The present invention discloses a heat-insulating solid wood composite floor and its processing equipment. The floor includes a surface layer, a composite layer and a bottom layer. The composite layer includes a flexible layer, a strengthening layer and a heat-insulating layer arranged in sequence from top to bottom. The flexible layer includes a number of buffer belts that are spliced with each other and are convex upward and concave downward. The strengthening layer includes a number of support skeletons in the shape of a capital "I". The heat-insulating layer is provided with heat-insulating holes filled with heat-insulating materials, and the heat-insulating holes are interconnected through heat-insulating channels filled with moisture-absorbing and heat-generating materials. The processing equipment includes a frame distributed in upper and lower layers. Each layer of the frame is provided with a number of conveying shafts and main grinding rollers. A pressing assembly is provided above each layer of the frame. A transfer elevator is provided on one side of the frame for conveying the floor between the upper layer of the frame and the lower layer of the frame. A flipping assembly is further provided on the lower layer of the frame in front of the conveying of the main grinding roller for flipping the front and back sides of the floor. The present invention has the characteristics of good heat-insulating effect of the floor, not easy to deform, and fast processing.

Description

Technical Field

[0001] The present invention relates to a composite floor, in particular to a heat-insulating solid wood composite floor and its processing equipment. Background Art

[0002] Floors are generally made of wood or other materials. There are many classifications of floors. Classified by structure, there are: solid wood floors, laminate floors, multi-layer solid wood composite floors, bamboo wood floors, anti-corrosion floors, cork floors, etc.; classified by function, there are: anti-static floors, anti-corrosion floors, heat-insulating floors, sound-insulating floors, etc.

[0003] Currently, in interior decoration, due to the cold weather in winter and the low indoor temperature, many families will choose to lay floor heating and heat-insulating floors indoors. For the construction of floor heating in interior decoration, generally, the water heating pipes or electric heating pipes are first laid on the ground, and then the heat-insulating floor is directly laid on the upper part of the water heating pipes or electric heating pipes. Currently, for heat-insulating floors, composite floors or solid wood floors are generally selected, but the composite floors and solid wood floors do not have good heat-insulating effects, and the water heating pipes need to continuously consume heat energy to heat the room, resulting in high energy consumption. Moreover, when the weather is relatively humid, they are prone to absorb moisture and deform, resulting in unstable floor structures, and the water heating pipes are easily trampled and burst.

[0004] Moreover, as the heat-insulating floor indoors, since the soles of the human feet directly contact the floor, the floor not only requires good heat-insulating effect, but also requires all surfaces to be relatively flat and smooth. However, for the current floor grinding technology, only one side of the floor can be ground each time. When the second side of the floor needs to be processed, the floor needs to be manually flipped, resulting in a large amount of manual labor, low overall grinding efficiency, lack of work continuity, and inability to meet the requirements of large-scale and comprehensive floor grinding production. Summary of the Invention

[0005] The purpose of the present invention is to provide a heat-insulating solid wood composite floor and its processing equipment. The present invention has the characteristics of good floor heat-insulating effect, not easy to deform, and fast processing.

[0006] The technical solution of the present invention: The heat-insulating solid wood composite floor includes a surface layer, a composite layer and a bottom layer. The composite layer includes a flexible layer, a strengthening layer and a heat-insulating layer arranged in sequence from top to bottom. The flexible layer includes a plurality of buffer bands that are spliced with each other and are in a convex-up and concave-down shape. The strengthening layer includes a plurality of I-shaped support skeletons. The upper ends of the support skeletons extend into the grooves of the buffer bands, and the lower ends of the support skeletons are connected to each other in sequence. The heat-insulating layer is provided with honeycomb-shaped heat-insulating holes, and the heat-insulating holes are interconnected through heat-insulating channels. Heat-insulating materials are filled in the heat-insulating holes, and moisture-absorbing and heat-generating materials are filled in the heat-insulating channels.

[0007] In the aforementioned heat-insulating solid wood composite floor, a sound-absorbing layer is attached to the convex surface of the buffer strip, and a plurality of air circulation holes are further provided in the flexible layer. One end of the air circulation hole communicates with the sound-absorbing layer, and the other end of the air circulation hole extends into the surface layer.

[0008] In the aforementioned heat-insulating solid wood composite floor, a strengthening cavity is provided between adjacent support skeletons, and a plurality of magnets are filled in the strengthening cavity. The outer periphery of the magnet is coated with a plurality of pig iron particles.

[0009] A processing device for a heat-insulating solid wood composite floor, which is used to process the aforementioned heat-insulating solid wood floor, includes a surface grinding mechanism. The surface grinding mechanism includes a frame distributed in upper and lower layers. Each layer of the frame is provided with a plurality of conveying shafts and main grinding rollers driven by the cooperation of a conveying motor and a conveying chain. A gap is left between adjacent conveying shafts and main grinding rollers, and the main grinding rollers of the upper layer and the main grinding rollers of the lower layer are staggered; a pressing assembly is provided above each layer of the frame, and a transfer lift is provided on one side of the frame for conveying the floor between the upper layer of the frame and the lower layer of the frame; a turning assembly for turning the front and back sides of the floor is further provided on the lower layer of the frame in front of the conveying of the main grinding rollers.

[0010] In the processing device for the aforementioned heat-insulating solid wood composite floor, a fixed frame is provided at the conveying starting end of each layer of the frame. A pushing cylinder vertically distributed is provided on the fixed frame. A pushing frame is provided on the piston rod of the pushing cylinder, and a horizontally distributed first side grinding roller driven by a grinding motor is rotatably connected to the pushing frame.

[0011] In the processing device for the aforementioned heat-insulating solid wood composite floor, the pressing assembly includes a limiting plate located above the corresponding layer of the frame. An adjusting screw is threadedly connected to the limiting plate. The upper end of the adjusting screw is fixedly connected with a rotating wheel. An adjusting plate is rotatably connected to the adjusting screw through a bearing. A plurality of pressing rods passing through the limiting plate are provided on the adjusting plate, and an elastic pressing wheel assembly is provided on the pressing rods.

[0012] In the processing device for the aforementioned heat-insulating solid wood composite floor, the elastic pressing wheel assembly includes a mounting seat fixed at the bottom end of the pressing rod. A ball bearing is provided in the mounting seat, balls are provided in the ball bearing, and a pressing spring connected to the mounting seat is provided at the bottom of the ball bearing.

[0013] In the processing device for the aforementioned heat-insulating solid wood composite floor, a connecting rod is penetrated through the adjusting plate. Both ends of the connecting rod are threaded sections, and threaded sleeves are threadedly connected to the threaded sections. First connecting rod, second connecting rod and third connecting rod distributed in a "Z" shape are provided on the threaded sleeve. Both ends of the second connecting rod are movably connected to the first connecting rod and the third connecting rod respectively. A compression spring is sleeved outside the second connecting rod, and both ends of the compression spring are connected to the first connecting rod and the third connecting rod respectively. A vertically distributed second side grinding roller is rotatably connected to the third connecting rod.

[0014] In the processing equipment for the aforementioned heat-insulating solid wood composite floor, the flipping assembly includes a pair of chassis connected to the frame. A rotating shaft driven by a rotating motor is provided on the chassis. A flipping arm is fixedly connected to the rotating shaft. A telescopic cylinder is connected to the flipping arm through a screw. An automatic suction cup is provided on the telescopic rod of the telescopic cylinder.

[0015] In the processing equipment for the aforementioned heat-insulating solid wood composite floor, a cleaning brush is provided below the main grinding roller. The bristles of the cleaning brush are in contact with the bottom of the main grinding roller. A storage box corresponding to the position of the cleaning brush is provided at the bottom of the frame.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] The present invention divides the floor into a surface layer, a composite layer, and a bottom layer. The composite layer includes a flexible layer, a strengthening layer, and a heat-insulating layer. A number of buffer bands that are convex upward and concave downward and are spliced with each other are arranged in the flexible layer to buffer the force applied to the floor, making the stepping more comfortable. The structural shape of the buffer bands effectively improves the load-bearing and compressive resistance of the floor. An I-shaped support framework is arranged in the strengthening layer, and the strength of the floor is improved by using the support framework, making it not easily deformed. The upper end of the support framework extends into the groove of the buffer band to further stabilize the structure of the flexible layer. A number of heat-insulating holes connected by heat-insulating channels are arranged in the heat-insulating layer. A moisture-absorbing and heat-generating material is filled in the heat-insulating channels, and a heat-insulating material is filled in the heat-insulating holes. The moisture-absorbing and heat-generating material can absorb the moisture in the floor and the air and convert it into heat for indoor needs. Long-term heat insulation can be carried out through the connected heat-insulating materials, and the moisture-absorbing and heat-generating material and the heat-insulating material are interconnected to ensure the uniformity and durability of the heat.

[0018] The present invention is provided with a double-layer frame, and a conveying shaft and a main grinding roller are arranged on each layer of the frame. In cooperation with the conveyor lift and the flipping assembly, the front and back sides of the floor are respectively conveyed and ground on the double-layer frame, realizing fast and comprehensive grinding treatment.

[0019] The present invention also sets a pressing assembly during the conveying process. The pressing assembly stably presses and fits the floor onto the conveying shaft and the main grinding roller, which can not only avoid the gaps generated when the floor is uneven, thereby ensuring the stability of the conveying, but also reduce the grinding gaps, thereby improving the comprehensiveness and integrity of the grinding. Description of the Drawings

[0020] Figure 1 is a schematic structural view of the floor of the present invention;

[0021] Figure 2 is a schematic structural view of the surface grinding mechanism of the present invention;

[0022] Figure 3 is a schematic structural view of the frame;

[0023] Figure 4 It is a schematic structural diagram of an elastic pressing wheel assembly;

[0024] Figure 5 It is a schematic structural diagram of a flipping assembly;

[0025] Figure 6 It is a schematic structural diagram of a second-side grinding roller.

[0026] The reference signs in the drawings are: 1, frame; 11, conveying shaft; 12, main grinding roller; 13, fixing bracket; 14, pushing cylinder; 15, pushing frame; 16, first-side grinding roller; 17, cleaning brush; 18, storage box; 2, pressing assembly; 21, limiting plate; 22, adjusting screw; 23, runner; 24, adjusting plate; 25, pressing rod; 26, elastic pressing wheel assembly; 261, mounting seat; 262, ball bearing; 263, ball; 264, pressing spring; 3, conveyor elevator; 31, lifting base; 32, lifting hydraulic cylinder; 33, lifting platform; 4, flipping assembly; 41, chassis; 42, rotating shaft; 43, flipping arm; 44, telescopic cylinder; 45, automatic suction cup; 51, connecting rod; 52, threaded section; 53, threaded sleeve; 54, first connecting rod; 55, second connecting rod; 56, third connecting rod; 57, compression spring; 58, second-side grinding roller; 61, surface layer; 62, bottom layer; 63, flexible layer; 631, buffer belt; 632, sound-absorbing layer; 633, air flow hole; 64, strengthening layer; 641, support framework; 642, strengthening cavity; 643, magnet; 644, pig iron particles; 65, heat-insulating layer; 651, heat-insulating hole; 652, heat-insulating channel; 653, heat-insulating material; 654, moisture-absorbing and heat-generating material. Detailed implementation manners

[0027] The present invention will be further described below in conjunction with embodiments, but it shall not be used as a basis for limiting the present invention.

[0028] Embodiment:

[0029] As Figure 1As shown, a thermal insulation solid wood composite floor comprises a surface layer 61, a composite layer and a bottom layer 62, wherein the composite layer comprises a flexible layer 63, a reinforcing layer 64 and a thermal insulation layer 65 arranged in sequence from top to bottom, wherein the flexible layer 63 comprises a plurality of mutually spliced ​​buffer strips 631 in an upper convex and lower concave shape, wherein a sound absorbing layer 632 is attached to the upper convex surface of the buffer strip 631, wherein a plurality of air flow holes 633 are also arranged in the flexible layer 63, wherein one end of the air flow hole 633 is connected to the sound absorbing layer 632, and the other end of the air flow hole 633 extends into the surface layer 61. The reinforcing layer 64 comprises a plurality of I-shaped support frames 641, wherein the upper ends of the support frames 641 extend into the grooves of the buffer strip 631, and the lower ends of the support frames 641 are sequentially connected to each other; and a reinforcing cavity 642 is arranged between adjacent support frames 641, wherein the reinforcing cavity 642 is filled with a plurality of magnets 643, and the outer periphery of the magnets 643 is coated with a plurality of cast iron particles 644. The thermal insulation layer 65 is provided with honeycomb-shaped thermal insulation holes 651 , which are interconnected through thermal insulation channels 652 , the thermal insulation holes 651 are filled with thermal insulation materials 653 , and the thermal insulation channels 652 are filled with moisture-absorbing and heat-generating materials 654 .

[0030] The present invention divides the floor into a surface layer 61, a composite layer and a bottom layer 62. A decorative layer can be arranged on the surface layer 61 to form an indoor decorative type of thermal insulation solid wood composite floor, wherein the composite layer includes a flexible layer 63, a reinforcement layer 64 and a thermal insulation layer 65. A plurality of mutually spliced ​​buffer strips 631 in an upper convex and lower concave shape are arranged in the flexible layer 63 to buffer the force applied to the floor, making it more comfortable to step on. The structural shape of the buffer strip 631, on the one hand, improves the load-bearing and pressure-resistant capacity of the floor, and on the other hand, increases the specific surface area of ​​the buffer strip 631. Combined with the arrangement of the sound-absorbing layer 632, the sound-absorbing and noise-reducing capacity of the floor can be enhanced. Air flow holes are also arranged on the upper convex surface of the buffer strip 631. The air flow holes are microporous in design. The air flow holes are used to discharge moisture and prevent bulging and deformation, and can further eliminate aerodynamic noise generated when stepping on.

[0031] An I-shaped support frame 641 is provided in the reinforcement layer 64, and the support frame 641 is used to improve the strength of the floor and make it not easy to deform; and the upper end of the support frame 641 extends into the groove of the buffer belt 631, further stabilizing the structure of the flexible layer 63 and avoiding damage due to excessive deformation; combined with the reinforcement cavity 642 between adjacent support frames 641, a number of pig iron particles 644 are adsorbed by the magnet 643, so as to further improve the strength and hardness of the floor, and the structure is stable and not easy to deform.

[0032] In the heat insulation layer 65, heat insulation holes 651 communicated by a number of heat insulation channels 652 are provided. A moisture-absorbing and heat-generating material 654 is filled in the heat insulation channels 652, and a heat insulation material 653 is filled in the heat insulation holes 651. The moisture-absorbing and heat-generating material 654 can absorb moisture in the floor and the air and convert it into heat required indoors. Through the connected heat insulation material 653, long-term heat insulation can be achieved, and the moisture-absorbing and heat-generating material 654 and the heat insulation material 653 are interconnected to ensure the uniformity and persistence of heat. In addition, for the magnets 643 and cast iron particles 644 in the strengthening layer 64, due to the relatively high specific heat capacity of the cast iron particles 644, heat can be stored for a long time. Even when the heat source stops generating heat, a certain amount of heat can still be maintained for a certain period of time, reducing heat loss. Of course, the cast iron particles 644 can also be other magnetic materials with relatively high specific heat capacities to improve the heat storage capacity and achieve long-term heat release.

[0033] As Figures 2-6 shown, a processing device for heat-insulated solid wood composite floors for processing heat-insulated solid wood composite floors includes a surface grinding mechanism. The surface grinding mechanism includes a frame 1 distributed in upper and lower layers. Each layer of the frame 1 is provided with a number of conveying shafts 11 and main grinding rollers 12 driven in cooperation by a conveying motor and a conveying chain. A gap is left between adjacent conveying shafts 11 and main grinding rollers 12, and the main grinding rollers 12 in the upper layer and the main grinding rollers 12 in the lower layer are staggered. A pressing assembly 2 is provided above each layer of the frame 1, and a transfer elevator 3 for conveying the floor between the upper layer of the frame 1 and the lower layer of the frame 1 is provided on one side of the frame 1. The transfer elevator 3 includes a lifting base 31, a lifting platform 33 driven by a lifting hydraulic cylinder 32 is provided on the lifting base 31, and a conveyor belt is provided on the lifting platform 33. A double-layer conveyor corresponding to the frame 1 is provided on the other side of the frame 1.

[0034] In the present invention, by providing a double-layer frame 1, and providing conveying shafts 11 and main grinding rollers 12 on each layer of the frame 1, and cooperating with the transfer elevator 3 and the flipping assembly 4, the front and back sides of the floor are respectively conveyed and ground on the double-layer frame 1, realizing fast and comprehensive grinding treatment.

[0035] The present invention also provides a pressing assembly 2 during the conveying process. The pressing assembly 2 stably presses and fits the floor onto the conveying shafts 11 and the main grinding rollers 12, which can not only avoid the gaps generated when the floor is uneven, thus ensuring the stability of the conveying, but also reduce the grinding gaps, thereby improving the comprehensiveness and integrity of the grinding.

[0036] At the conveying starting end of each layer of the frame 1, a fixing frame 13 is provided. A pushing cylinder 14 vertically distributed is provided on the fixing frame 13. A pushing frame 15 is provided on the piston rod of the pushing cylinder 14. A horizontally distributed first side grinding roller 16 driven by a grinding motor is rotatably connected to the pushing frame 15.

[0037] The pressing assembly 2 includes a limiting plate 21 located above the frame 1 at the corresponding layer. An adjusting screw 22 is threadedly connected to the limiting plate 21. The upper end of the adjusting screw 22 is fixedly connected to a rotating wheel 23. An adjusting plate 24 is rotatably connected to the adjusting screw 22 through a bearing. A plurality of pressing rods 25 passing through the limiting plate 21 are provided on the adjusting plate 24. An elastic pressing wheel assembly 26 is provided on the pressing rod 25. The elastic pressing wheel assembly 26 includes a mounting seat 261 fixed to the bottom end of the pressing rod 25. A ball bearing 262 is provided in the mounting seat 261. A ball 263 is provided in the ball bearing 262. A pressing spring 264 connected to the mounting seat 261 is provided at the bottom of the ball bearing 262. By rotating the rotating wheel 23, the adjusting screw 22 is driven to rotate, so that the adjusting screw 22 vertically moves on the limiting plate 21, thereby driving the adjusting plate 24 and the elastic pressing wheel assembly 26 to move up and down to stably press floors with different thicknesses, improving the stability of grinding and conveying.

[0038] A connecting rod 51 passes through the adjusting plate 24. Both ends of the connecting rod 51 are threaded sections 52. Threaded sleeves 53 are threadedly connected to the threaded sections 52. First connecting rods 54, second connecting rods 55 and third connecting rods 56 distributed in a "Z" shape are provided on the threaded sleeves 53. Both ends of the second connecting rod 55 are movably connected to the first connecting rod 54 and the third connecting rod 56 respectively. A compression spring 57 is sleeved outside the second connecting rod 55. Both ends of the compression spring 57 are connected to the first connecting rod 54 and the third connecting rod 56 respectively. A second side grinding roller 58 vertically distributed is rotatably connected to the third connecting rod 56. The threaded sleeve 53 is threadedly connected to the threaded section 52, and the position of the threaded sleeve 53 can be adjusted, so as to adjust the distance between the second side grinding roller 58 and the side surface of the floor. With the arrangement of the compression spring 57, it is made to fit the side surface of the floor. As the floor moves driven by the conveying shaft 11, the second side grinding roller 58 is driven to rotate, thereby grinding the left and right side surfaces of the floor.

[0039] On the lower layer of the frame 1, a turning assembly 4 for turning the front and back sides of the floor is also provided on the front side of the conveyance of the main grinding roller 12. The turning assembly 4 includes a pair of chassis 41 connected to the frame 1. A rotating shaft 42 driven by a rotating motor is provided on the chassis 41. A turning arm 43 is fixedly connected to the rotating shaft 42. A telescopic cylinder 44 is connected to the turning arm 43 through a screw. An automatic suction cup 45 is provided on the telescopic rod of the telescopic cylinder 44. The position of the automatic suction cup 45 is adjusted by the screw. The rotating shaft 42 is driven by the rotating motor to rotate, and the rotating shaft 42 drives the turning arm 43 to rotate, so that the automatic suction cup 45 on the telescopic cylinder 44 aligns with the floor, adsorbs the floor, and then turns again, so that the bottom surface of the floor faces the automatic suction cup 45 on the other turning arm 43. The automatic suction cup 45 on the other turning arm 43 adsorbs the bottom surface of the floor. Then the first adsorbed automatic suction cup 45 is released, and the other automatic suction cup 45 turns the floor to the state with the bottom surface facing up. Then, the other side and the left and right sides of the floor are polished by the main grinding roller 12 and the second side grinding roller 58.

[0040] A cleaning brush is provided below the main grinding roller 12. The bristles of the cleaning brush 17 are in contact with the bottom of the main grinding roller 12. A storage box 18 corresponding to the position of the cleaning brush 17 is provided at the bottom of the frame 1. The provided cleaning brush 17 can remove the debris ground out from the main grinding roller 12 and drop it into the storage box 18 through the gap between the conveying shaft 11 and the main grinding roller 12.

[0041] Working principle: The solid wood composite floor first passes through the upper layer of the frame 1 and is first conveyed by the conveying shaft 11 to the first side grinding roller 16. The first side grinding roller 16 descends to block the solid wood composite floor. On the one hand, it adjusts the position of the floor to keep it in a horizontal and correct state, which is convenient for the subsequent accurate grinding of the main grinding roller 12 and the second side grinding roller 58. At the same time, the first side grinding roller 16 also grinds the front side of the floor under the drive of the grinding motor. After the treatment, the first side grinding roller 16 is lifted up so that it passes through the main grinding roller 12 and the second side grinding roller 58 respectively for grinding the bottom surface and the left and right sides.

[0042] After grinding, with the conveyance of the conveying shaft 11, the floor is conveyed to the transfer elevator 3, and the transfer elevator 3 conveys the floor in the reverse direction to the lower layer of the frame 1. The first side grinding roller 16 on the lower layer descends to block the solid wood composite floor, which not only adjusts the position of the floor to facilitate the subsequent accurate turning of the floor by the turning assembly 4, but also grinds the rear side of the floor. After grinding, the floor is conveyed to the turning assembly 4, and the turning assembly 4 turns the front and back sides of the floor. After turning, the floor is conveyed again so that it passes through the main grinding roller 12 and the second side grinding roller 58 in sequence for secondary grinding of the other side and the left and right sides, thus realizing the pipeline processing of comprehensively grinding the six sides of the floor at one time.

[0043] During the grinding process of the main grinding roller 12, the pressing assembly 2 stably presses the floor onto the conveying shaft 11 and the main grinding roller 12, making it fit perfectly. This can avoid the generation of gaps when the floor is uneven, thus ensuring the stability of conveying, and also reduce the grinding gaps, thereby improving the comprehensiveness and integrity of grinding. The pressing assembly 2 is in the form of elastic pressing wheels, which can ensure that the uneven positions in the local area of the floor can also fit with the conveying shaft 11 and the main grinding roller 12, and can move freely along with the conveying of the conveying shaft 11, with free movement.

[0044] During the grinding process of the main grinding roller 12, the cleaning brush 17 at the bottom removes the debris ground out on the main grinding roller 12, and then the debris falls into the storage box 18 through the gap between the conveying shaft 11 and the main grinding roller 12. The debris ground out can also be removed by means of negative pressure adsorption, reducing the pollution in the workshop and improving the grinding quality.

Claims

1. Insulated solid wood composite floor, characterized in that: It includes a surface layer (61), a composite layer and a bottom layer (62). The composite layer includes a flexible layer (63), a strengthening layer (64) and a heat-insulating layer (65) which are arranged in sequence from top to bottom. The flexible layer (63) includes a number of buffer belts (631) that are spliced with each other and have a convex-up and concave-down shape. The strengthening layer (64) includes a number of I-shaped support skeletons (641). The upper ends of the support skeletons (641) extend into the grooves of the buffer belts (631), and the lower ends of the support skeletons (641) are connected to each other in sequence. The heat-insulating layer (65) is provided with honeycomb-shaped heat-insulating holes (651). The heat-insulating holes (651) are interconnected through heat-insulating channels (652). Heat-insulating materials (653) are filled in the heat-insulating holes (651), and moisture-absorbing and heat-generating materials (654) are filled in the heat-insulating channels (652).

2. The heat-insulating solid wood composite floor according to claim 1, wherein: The convex surface of the buffer belt (631) is attached with a sound-absorbing layer (632). A number of air circulation holes (633) are also provided in the flexible layer (63). One end of the air circulation holes (633) is communicated with the sound-absorbing layer (632), and the other end of the air circulation holes (633) extends into the surface layer (61).

3. The heat-insulating solid wood composite floor according to claim 1, characterized in that: Strengthening cavities (642) are provided between adjacent support skeletons (641). A number of magnets (643) are filled in the strengthening cavities (642), and a number of pig iron particles (644) are coated on the outer periphery of the magnets (643).

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