阅读说明：本技术 一种用于工程陶瓷加工的车床 (Lathe for engineering ceramic machining ) 是由 李霞亲 于 2021-01-11 设计创作，主要内容包括：本发明涉及陶瓷车削技术领域,尤其是涉及一种用于工程陶瓷加工的车床,包括机身以及位于所述机身内的工作腔,所述工作腔内可上下移动的设置有工作块,所述工作块内可转动的设置有转动块,所述转动块内设有左右对称且开口向上的夹紧腔,所述夹紧腔内可转动的设置有左右对称且旋向相反的第一螺纹杆,所述第一螺纹杆外表面螺纹配合连接有用于夹固陶瓷件的夹块,本发明提供一种用于工程陶瓷加工的车床,该发明通过在车削的过程中对陶瓷件的表面涂抹硅酸溶液提高其在切削过程中的表面粗糙程度,利用制冷器在切削的过程中喷出冷气减少车刀表面的热量以及损耗,在车削的过程中通过齿条与摇杆的卡和有效减少升降过程中产生的震动,提高了切削的效率。(The invention relates to the technical field of ceramic turning, in particular to a lathe for engineering ceramic processing, which comprises a lathe body and a working cavity positioned in the lathe body, wherein the working cavity can be internally provided with a working block which can move up and down, the working block is rotatably provided with a rotating block, the rotating block is internally provided with clamping cavities which are bilaterally symmetrical and have upward openings, first threaded rods which are bilaterally symmetrical and have opposite rotating directions are rotatably arranged in the clamping cavities, the outer surface of the first threaded rod is in threaded fit connection with a clamping block for clamping a ceramic piece, the invention provides the lathe for engineering ceramic processing, the invention improves the surface roughness of the ceramic piece in the cutting process by smearing silicic acid solution on the surface of the ceramic piece in the turning process, and reduces the heat and the loss of the surface of a turning tool by using a refrigerator to spray cold air in the cutting process, the vibration generated in the lifting process is effectively reduced through the clamping of the rack and the rocker in the turning process, and the cutting efficiency is improved.)

1. A lathe for engineering ceramics processing comprises a lathe body and a working cavity positioned in the lathe body, and is characterized in that: a working block is arranged in the working cavity and can move up and down, a rotating block is rotatably arranged in the working block, clamping cavities which are bilaterally symmetrical and have upward openings are arranged in the rotating block, first threaded rods which are bilaterally symmetrical and have opposite rotating directions are rotatably arranged in the clamping cavities, clamping blocks for clamping ceramic parts are connected to the outer surfaces of the first threaded rods in a threaded fit manner, the first threaded rods are dynamically connected to rotary air cylinders embedded in the middle end walls of the clamping cavities, moving grooves with downward openings are arranged in the lower end walls of the working block, first moving blocks are arranged in the moving grooves and can move left and right, first moving cavities with upward openings are arranged in the lower end walls of the working cavity, second moving blocks are arranged in the first moving cavities and can move left and right, and rocking bars which are symmetrical to each other are hinged and connected between the bottom walls of the first moving blocks and the second moving blocks and the working, the working cavity is internally provided with a processing device which drives the working block to move upwards for processing through the rotation of the rocker, the right side end wall of the working cavity is fixedly provided with a fixed rod, the outer surface of the fixed rod is fixedly connected with a turning tool through a screw, the top end of the working cavity is fixedly provided with a refrigeration block, the refrigeration block is internally provided with a refrigerator for cooling the turning tool and a ceramic piece, the left side end wall of the working cavity is internally provided with a second moving cavity with a right opening, the second moving cavity is internally provided with a water absorption block which can move leftwards and rightwards and is provided with a large amount of silicic acid solution, the second moving cavity is internally provided with a moving device which enables the water absorption block to move rightwards to be contacted with the ceramic piece for smearing through a rotatable screw rod and a fixed key which is fixedly arranged at the bottom end of the second moving cavity and is superposed with the gap of the screw rod when the turning tool starts to, the third moving cavity is internally provided with a rack which can move left and right and is symmetrical up and down and can be superposed with a left notch of the opening of the outer surface of the rocker on the left side, and the third moving cavity is internally provided with a damping device which can increase the stability in the machining process through the superposition of the rack and the notch.

2. The lathe for engineering ceramic machining according to claim 1, wherein: the motor is embedded in the end wall of the right side of the first moving cavity, the motor spindle is connected with the second moving block in a threaded fit mode, the second threaded rod extends rightwards into the first moving cavity, the outer surface of the second threaded rod is fixedly provided with a first worm block, the front side of the first worm block is meshed with a first worm wheel, the end, extending upwards, of the first worm wheel spindle is fixedly provided with a first belt wheel, the second belt wheel is rotatably arranged in the working cavity, the first belt wheel is connected with the second belt wheel in a transmission mode through a first transmission belt, the second belt wheel spindle extends upwards into a cavity with the opening facing left, a spline shaft is connected in a spline fit mode with the outer surface of the spline shaft, a first gear is fixedly arranged on the outer surface of the spline shaft, the rotating block extends downwards into the rotating cavity, and the outer surface of the rotating block is fixedly provided with a second gear meshed with the.

3. The lathe for engineering ceramic machining according to claim 1, wherein: the second threaded rod extends leftwards to pass through the first gear cavity, a third belt wheel is fixedly arranged on the outer surface of the second threaded rod, a fourth belt wheel which is in transmission connection with the third belt wheel through a second transmission belt is rotatably arranged in the second moving cavity, the screw rod is connected with the inner thread of the fourth belt wheel main shaft in a matching way, the second threaded rod extends rightwards into the second transmission cavity, the spline sleeve shaft is connected with the outer surface of the fourth belt wheel main shaft in a spline matching way, the tail end of the spline sleeve shaft is fixedly provided with a sector bevel gear, a transmission shaft is rotatably arranged in the second transmission cavity, a magnet is fixedly arranged at the tail end of the transmission shaft, an electromagnet which can be attracted with the magnet after being electrified is fixedly arranged at the left end of the sector bevel gear, the outer surface of the transmission shaft is fixedly provided with a transmission bevel gear which can be meshed with the fan-shaped bevel gear, and a spring is elastically connected between the left end of the fan-shaped bevel gear and the magnetic block.

4. The lathe for engineering ceramic machining according to claim 1, wherein: the transmission shaft extends upwards to extend through the second gear cavity, the outer surface of the transmission shaft is fixedly provided with a second worm block which is symmetrical up and down and opposite in rotation direction, the front side of the second worm block is engaged with a second worm wheel, the tail end of the second worm wheel main shaft extending rightwards is fixedly provided with an incomplete gear, the middle of the incomplete gear is engaged with a third gear, the third gear main shaft, namely a worm, extends rightwards to a third moving cavity, the damping device comprises a third worm wheel which is symmetrical up and down and engaged with the worm, and the tail end of the third worm wheel main shaft extending backwards is fixedly provided with a fourth gear engaged with the rack.

5. The lathe for engineering ceramic machining according to claim 1, wherein: the transmission shaft extends upwards into a third transmission cavity, belt pulleys which are symmetrical in front and back and are in transmission connection through a third transmission belt are rotatably arranged in the point transmission cavity, the belt pulley at the front side is fixedly arranged at the top end of the transmission shaft, a fifth gear is fixedly arranged on the downward extending outer surface of the main shaft of the belt pulley, a transmission rack is meshed with the front side of the fifth gear, the transmission rack extends rightwards to a third gear cavity which is symmetrical front and back, a sixth gear is meshed at one opposite side, a winding wheel is fixedly arranged on the upward extending outer surface of the sixth gear device, a torsion spring is elastically connected between the main shaft of the winding wheel and the top end of the third gear cavity, a fourth moving cavity with a left opening and a right opening is arranged in the end wall of the middle of the third gear cavity, a sealing block capable of moving back and forth in the fourth moving cavity and preventing silicic acid solution in the water absorption block from leaking is arranged in the fourth moving cavity, and the sealing block is fixedly connected with the winding wheel through a pull rope.

Technical Field

The invention relates to the technical field of ceramic turning, in particular to a lathe for processing engineering ceramics.

Background

Ceramics are inorganic non-metallic materials formed by high-temperature sintering, have many excellent properties such as high temperature resistance, abrasion resistance, corrosion resistance, thermal shock resistance and the like in the aspects of thermal and mechanical properties, and are widely applied to various fields. The preparation process mainly comprises the steps of powder preparation, blank preparation, molding and sintering. The characteristics of high strength, high hardness, high brittleness and the like of the ceramic material can bring great difficulty to finish machining, and the defects of cracks and burns can be generated by careless treatment.

Disclosure of Invention

The invention aims to provide a lathe for processing engineering ceramics, which can overcome the defects in the prior art, thereby improving the practicability of equipment.

The technical scheme adopted by the invention for solving the technical problems is as follows: the invention relates to a lathe for processing engineering ceramics, which comprises a lathe body and a working cavity positioned in the lathe body, wherein the working cavity is internally provided with a working block which can move up and down, the working block is internally rotatably provided with a rotating block, the rotating block is internally provided with clamping cavities which are bilaterally symmetrical and have upward openings, the clamping cavities are rotatably provided with first threaded rods which are bilaterally symmetrical and have opposite rotating directions, the outer surfaces of the first threaded rods are in threaded fit connection with clamping blocks for clamping ceramic pieces, the first threaded rods are in power connection with a rotary cylinder embedded in the middle end wall of the clamping cavities, the lower end wall of the working block is internally provided with a moving groove with a downward opening, the moving groove is internally provided with a first moving block which can move left and right, the lower end wall of the working cavity is internally provided with a first moving cavity with an upward opening, and the first moving block is internally, the first moving block, the second moving block, the bottom wall of the working cavity and rocking bars which are symmetrical to each other are hinged to each other and connected between the working blocks, a processing device which is driven by the rotation of the rocking bars to move the working blocks upwards for processing is arranged in the working cavity, a fixing rod is fixedly arranged at the end wall of the right side of the working cavity, a turning tool is fixedly connected to the outer surface of the fixing rod through screws, a refrigerating block is fixedly arranged at the top end of the working cavity, a refrigerator which is used for cooling the turning tool and a ceramic piece is arranged in the refrigerating block, a second moving cavity with a right opening is arranged in the end wall of the left side of the working cavity, a water absorbing block which contains a large amount of silicic acid solution is arranged in the second moving cavity in a movable mode, and when the turning tool starts to work and cuts the ceramic piece, the water absorbing block is moved to the right side and is contacted with the ceramic piece through a rotatable screw The painting device comprises a moving device, a third moving cavity with a right opening is arranged in the lower side end wall of the second moving cavity, racks which are symmetrical up and down and can coincide with a left opening notch on the outer surface of the rocker on the left side are arranged in the third moving cavity in a left-and-right moving mode, and a damping device which can increase the stability in the machining process through the coincidence of the racks and the notches is arranged in the third moving cavity.

Furthermore, a motor is embedded in the end wall of the right side of the first moving cavity, the outer surface of a main shaft of the motor, namely a second threaded rod, is in threaded fit connection with the second moving block, the second threaded rod extends rightwards into the first transmission cavity, the outer surface is fixedly provided with a first worm block, a first worm wheel is meshed at the front side of the first worm block, a first belt wheel is fixedly arranged at the upward extending tail end of a main shaft of the first worm wheel, a second belt wheel is rotatably arranged in the working cavity, the first belt wheel is in transmission connection with the second belt wheel through a first transmission belt, the second belt wheel main shaft extends upwards to the cavity with the left opening, a spline shaft is connected with the outer surface of the second belt wheel main shaft in a spline fit manner, the outer surface of the spline shaft is fixedly provided with a first gear, the main shaft of the rotating block extends downwards into the rotating cavity, and the outer surface of the rotating block is fixedly provided with a second gear meshed with the first gear.

Furthermore, the second threaded rod extends leftwards to pass through the first gear cavity, a third belt wheel is fixedly arranged on the outer surface, a fourth belt wheel which is in transmission connection with the third belt wheel through a second transmission belt is rotatably arranged in the second moving cavity, the screw rod is connected with the inner thread of the fourth belt wheel main shaft in a matching way, the second threaded rod extends rightwards into the second transmission cavity, the spline sleeve shaft is connected with the outer surface of the fourth belt wheel main shaft in a spline matching way, the tail end of the spline sleeve shaft is fixedly provided with a sector bevel gear, a transmission shaft is rotatably arranged in the second transmission cavity, a magnet is fixedly arranged at the tail end of the transmission shaft, an electromagnet which can be attracted with the magnet after being electrified is fixedly arranged at the left end of the sector bevel gear, the outer surface of the transmission shaft is fixedly provided with a transmission bevel gear which can be meshed with the fan-shaped bevel gear, and a spring is elastically connected between the left end of the fan-shaped bevel gear and the magnetic block.

Furthermore, the transmission shaft extends upwards to extend through the second gear cavity, a second worm block which is symmetrical up and down and opposite in rotation direction is fixedly arranged on the outer surface of the transmission shaft, a second worm wheel is meshed on the front side of the second worm block, an incomplete gear is fixedly arranged at the tail end of a main shaft of the second worm wheel which extends rightwards, a third gear is meshed in the middle of the incomplete gear, the main shaft of the third gear, namely the worm, extends rightwards to the third moving cavity, the damping device comprises a third worm wheel which is symmetrical up and down and meshed with the worm, and a fourth gear meshed with the rack is fixedly arranged at the tail end of the main shaft of the third worm wheel which extends backwards.

Furthermore, the transmission shaft extends upwards into a third transmission cavity, belt pulleys which are symmetrical front and back and are in transmission connection through a third transmission belt are rotatably arranged in the point transmission cavity, the belt pulley on the front side is fixedly arranged at the top end of the transmission shaft, a fifth gear is fixedly arranged on the downward extending outer surface of the main shaft of the belt pulley, a transmission rack is meshed at the front side of the fifth gear, the transmission rack extends rightwards into the third gear cavity which is symmetrical front and back, a sixth gear is meshed at one opposite side, a winding wheel is fixedly arranged on the upward extending outer surface of the sixth gear device, a torsion spring is elastically connected between the main shaft of the winding wheel and the top end of the third gear cavity, a fourth moving cavity with a left opening and a right opening is arranged in the middle end wall of the third gear cavity, and a sealing block which can move back and forth is arranged in the fourth moving cavity and is used for, the sealing block is fixedly connected with the winding wheel through a pull rope.

The invention has the beneficial effects that: the invention provides a lathe for processing engineering ceramics, which improves the surface roughness of a ceramic piece in the cutting process by coating a silicic acid solution on the surface of the ceramic piece in the turning process, reduces the heat and the loss of the surface of a turning tool by using cold air sprayed out by a refrigerator in the cutting process, effectively reduces the vibration generated in the lifting process by clamping a rack and a rocker in the turning process, and improves the cutting efficiency.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

The invention is further illustrated with reference to the following figures and examples.

Fig. 1 is a schematic overall structure diagram of a lathe for engineering ceramic machining according to the present invention.

Fig. 2 is a schematic view of the structure a-a in fig. 1.

FIG. 3 is a schematic diagram of B-B in FIG. 1.

Fig. 4 is a schematic view of the structure of C-C in fig. 1.

Fig. 5 is an enlarged schematic view of the structure at D in fig. 1.

Detailed Description

The invention will now be described in detail with reference to fig. 1-5, wherein for ease of description the orientations described hereinafter are now defined as follows: the up, down, left, right, and front-back directions described below correspond to the up, down, left, right, and front-back directions in the projection relationship of fig. 1 itself.

The lathe for engineering ceramic processing described with reference to fig. 1-5 comprises a machine body 10 and a working chamber 15 located in the machine body 10, wherein a working block 80 is arranged in the working chamber 15 in a vertically movable manner, a rotating block 72 is rotatably arranged in the working block 80, a clamping chamber 71 which is bilaterally symmetrical and has an upward opening is arranged in the rotating block 72, a first threaded rod 73 which is bilaterally symmetrical and has an opposite rotation direction is rotatably arranged in the clamping chamber 71, a clamping block 75 for clamping a ceramic piece is connected to the outer surface of the first threaded rod 72 in a threaded manner, the first threaded rod 73 is dynamically connected to a rotary cylinder 74 embedded in the middle end wall of the clamping chamber 71, a moving groove 79 with a downward opening is arranged in the lower end wall of the working block 80, a first moving block 78 is arranged in the moving groove 79 in a laterally movable manner, a first moving chamber 81 with an upward opening is arranged in the lower end wall of the working chamber 15, a second moving block 56 is arranged in the first moving cavity 81 and can move left and right, rocker arms 69 which are symmetrical to each other are hinged between the bottom wall of the first moving block 78 and the second moving block 56 and between the bottom wall of the working cavity 15 and the working block 80, a processing device 201 which drives the working block 80 to move up for processing is arranged in the working cavity 15 through the rotation of the rocker arms 69, a fixed rod 11 is fixedly arranged at the right end wall of the working cavity 15, a turning tool 13 is fixedly connected to the outer surface of the fixed rod 11 through a screw 12, a refrigerating block 14 is fixedly arranged at the top end of the working cavity 15, a refrigerator 16 used for cooling the turning tool 13 and ceramic pieces is arranged in the refrigerating block 14, a second moving cavity 38 with an opening towards the right is arranged in the left end wall of the working cavity 15, and a water absorption block 40 containing a large amount of silicic acid solution is arranged in, the second moving cavity 38 is internally provided with a moving device 202 which enables the water absorption block 40 to move right to contact with the ceramic piece for smearing through a rotatable screw rod 39 and a fixed key fixedly superposed at the bottom end of the second moving cavity 38 with the gap of the screw rod 39 when the turning tool 13 starts to work for cutting the ceramic piece, the lower side end wall of the second moving cavity 38 is internally provided with a third moving cavity 42 with a right opening, the third moving cavity 42 is internally provided with vertically symmetrical racks 43 which can be superposed with a left gap 70 of the opening of the outer surface of the rocker 69 on the left side in a left-right moving manner, and the third moving cavity 42 is internally provided with a damping device 203 which can increase the stability in the machining process through the superposition of the racks 43 and the gap 70.

Beneficially, a motor 66 is embedded in the right end wall of the first moving cavity 81, a main shaft of the motor 66, namely, an outer surface of a second threaded rod 58, is in threaded fit connection with the second moving block 56, the second threaded rod 58 extends rightwards into a first transmission cavity 57, a first worm block 59 is fixedly arranged on the outer surface, a first worm wheel 60 is engaged on the front side of the first worm block 59, a first belt wheel 61 is fixedly arranged at the upward extending tail end of the main shaft of the first worm wheel 60, a second belt wheel 68 is rotatably arranged in the working cavity 15, the first belt wheel 61 is in transmission connection with the second belt wheel 68 through a first transmission belt 62, the main shaft of the second belt wheel 68 extends upwards into a cavity 63 with a left opening, a spline 65 is in spline fit connection with the outer surface, a first gear 67 is fixedly arranged on the outer surface of the spline 65, and a main shaft of the rotating block 72 extends downwards into a rotating cavity 76, a second gear 77 engaged with the first gear 67 is fixedly provided on the outer surface.

Advantageously, the second threaded rod 58 extends through the first gear cavity 34 leftwards, a third belt wheel 35 is fixedly arranged on the outer surface, a fourth belt wheel 37 in transmission connection with the third belt wheel 35 through a second transmission belt 36 is rotatably arranged in the second moving cavity 38, the helical rod 39 is connected to the inside of the fourth belt wheel main shaft in a threaded fit manner, the second threaded rod 34 extends rightwards into the second transmission cavity 22, a spline sleeve shaft 29 is connected to the outer surface in a spline fit manner, a sector bevel gear 30 is fixedly arranged at the tail end of the spline sleeve shaft 29, a transmission shaft 24 is rotatably arranged in the second transmission cavity 22, a magnetic block 26 is fixedly arranged at the tail end of the transmission shaft 24, an electromagnet 28 which can be attracted with the magnetic block 26 after being electrified is fixedly arranged at the left end of the sector bevel gear 30, a transmission bevel gear 25 which can be meshed with the sector bevel gear 30 is fixedly arranged on the, a spring 27 is elastically connected between the left end of the sector bevel gear 30 and the magnetic block 26.

Advantageously, the transmission shaft 24 extends upwards through the second gear cavity 21, the outer surface is fixedly provided with a second worm block 32 which is symmetrical up and down and has an opposite rotation direction, the front side of the second worm block 32 is engaged with a second worm wheel 33, the right extending end of the main shaft of the second worm wheel 33 is fixedly provided with an incomplete gear 47, the middle of the incomplete gear 47 is engaged with a third gear 44, the main shaft of the third gear 44, namely a worm 86, extends rightwards into the third moving cavity 42, the damping device 203 comprises a third worm wheel 46 which is symmetrical up and down and is engaged with the worm 86, and the rear extending end of the main shaft of the third worm wheel 46 is fixedly provided with a fourth gear 45 which is engaged with the rack 43.

Beneficially, the transmission shaft 24 extends upwards into the third transmission cavity 17, a belt pulley 21 which is symmetrical in front and back and is in transmission connection through a third transmission belt 22 is rotatably arranged in the point transmission cavity 17, the belt pulley 21 at the front side is fixedly arranged at the top end of the transmission shaft 24, a fifth gear 19 is fixedly arranged on the downward extending outer surface of the main shaft of the belt pulley 21, a transmission rack 18 is engaged at the front side of the fifth gear 19, the transmission rack 18 extends rightwards into a third gear cavity 51 which is symmetrical in front and back, a sixth gear 55 is engaged at the opposite side, a winding wheel 53 is fixedly arranged on the upward extending outer surface of the sixth gear 55, a torsion spring 52 is elastically connected between the main shaft of the winding wheel 53 and the top end of the third gear cavity 51, a fourth moving cavity 48 with a left and right opening is arranged in the middle end wall of the third gear cavity 51, a sealing block 50 which can prevent the silicic acid solution in the water absorption block 40 from leaking is arranged in the fourth moving cavity 48, the closing block 50 is fixedly connected with the winding wheel 53 through a pull rope 54.

The fixing and connecting method in this embodiment includes, but is not limited to, bolting, welding, and the like.

Sequence of mechanical actions of the whole device:

when the device of the present invention is in operation, a ceramic piece is put on the rotating block 72, the rotating cylinder 74 is started to drive the first threaded rod 73 to rotate, thereby driving the clamping blocks 75 to move in opposite directions to clamp the ceramic piece, the motor 66 is started to drive the second threaded rod 58 to rotate, thereby driving the second moving block 56 to move right, thereby driving the rocker 69 to rotate, thereby driving the first moving block 78 to move right, thereby driving the lifting block 80 to move up and simultaneously driving the first gear 67 to move up, at this time, the first worm block 59 rotates to drive the first worm wheel 60 to rotate, thereby driving the first belt wheel 61 to rotate, thereby driving the second belt wheel 68 to rotate, thereby driving the first gear 67 to rotate, thereby driving the second gear 77 to rotate, thereby driving the rotating block 72 to rotate, and simultaneously the third belt wheel 35 drives the fourth belt wheel 37 to rotate, thereby driving the screw rod 39 to move right, the bevel gear sector 30 rotates, when the working block 80 rises to a certain height, the electromagnet 28 is powered on and the refrigerator 16 is turned on to start refrigeration, the bevel gear sector 30 is meshed with the bevel gear drive 24 to rotate, thereby driving the second worm block 32 to rotate, thereby driving the second worm 32 to rotate, thereby driving the incomplete gear 47 to rotate, thereby driving the third gear 44 to rotate, thereby driving the third worm gear 46 to rotate, thereby driving the fourth gear 45 to rotate, thereby driving the rack 43 to move right into the notch 70 to coincide and then automatically retract along with the reciprocating forward and reverse rotation of the third gear 44, by coinciding with the notch 70, the vibration during the movement of the lifting block 80 is reduced, the drive shaft 24 drives the belt pulley 21 to rotate, thereby driving the drive rack 18 to move right, thereby driving the sixth gear 55 to rotate, thereby driving the winding wheel 53 to rotate and tighten the pull rope 54 to make the closing block 50 move oppositely and release the opening so that the water absorption block 40 passes through, the turning tool contacts the surface of the ceramic piece on the other side with the water absorption block 40 in the process of cutting the ceramic piece and coats silicic acid solution to make the ceramic piece not easy to crack and increase the surface roughness of the ceramic piece, meanwhile, the loss of the turning tool caused by overheating is reduced under the action of the refrigerator 16, the processing stability is improved, and the motor 66 is reversed after the processing is finished to reset the device.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.