A crystal resonator patch device

Abstract

The invention discloses a crystal resonator patch device, comprising: a shell, which is arranged in a patch machine, and the top of the shell is an open end; a tray, which is used to place the crystal resonator, and the tray comprises: a frame, which is provided with a plurality of notches, and rubber grooves are arranged in the notches, and the rubber grooves are used to store the crystal resonator; a feeding assembly, which is arranged in the shell, and the feeding assembly comprises: a chain, which is provided with at least two groups, and both ends of the chain are provided with driving teeth, and driving rods are fixedly connected in the driving teeth, and both ends of the driving rods are rotatably connected to the inner wall of the shell, and connecting pieces are arranged in an array on the chain, and the connecting pieces move synchronously with the chain, and clamping blocks are fixedly connected to the connecting pieces, and the trays are placed between the clamping blocks, and clamping plates are fixedly connected between the clamping blocks and the clamping blocks on the adjacent chains; a pushing mechanism, which is arranged on the upper side of the shell, and the pushing mechanism is used to push the empty tray out of the shell.

Description

Technical Field

[0001] The invention relates to the technical field of resonator patches, in particular to a crystal resonator patch device. Background Art

[0002] In the existing automated surface mount (SMT) technology, crystal resonators usually need to be surface mounted by a placement machine. Crystal resonators are electronic components for stable frequencies and are widely used in communications, computers, automotive electronics and other fields. Due to the small size and high precision requirements of crystal resonators, they must be mounted using precision automated equipment. At present, the common surface mounting process of crystal resonators is to arrange the crystal resonators neatly in a tray, and each tray usually holds multiple crystal resonators. The grooves inside the tray are used to accurately locate and place the crystal resonators to ensure the stability of the components during transportation and feeding. During operation, the staff needs to place the tray filled with crystal resonators into the feeding position of the placement machine. The feeding device takes out the crystal resonators in the tray one by one through the suction cup system and places them accurately on the predetermined pad position;

[0003] The specific steps of the process are as follows:

[0004] Pallet loading: The staff first puts the pallet with the crystal resonator into the slot in the placement machine feeder;

[0005] Suction cup material collection: The feeding device takes out the crystal resonators from the tray one by one through the suction cup. The suction cup system extracts the crystal resonator from the tray and accurately places it on the pad on the PCB.

[0006] Tray replacement process: When all crystal resonators in the tray are taken out, the staff needs to manually remove the empty tray and put the new full tray into the feeding position;

[0007] At this point, the SMT machine will stop for tray change and wait for the new tray to be loaded;

[0008] The pallet changing process in the prior art requires downtime, which reduces the effective working time of the production line and affects the overall production efficiency. The pallet changing operation usually takes a certain amount of time to remove the empty pallet and load the full pallet, which not only increases labor costs but also reduces the level of automation.

[0009] To this end, we propose a crystal resonator patch device. Summary of the invention

[0010] The purpose of the present invention is to provide a crystal resonator patch device to solve the problems raised in the above background technology. To achieve the above purpose, the present invention provides the following technical solutions: a crystal resonator patch device, comprising:

[0011] A housing, wherein the housing is arranged in the placement machine, and the top of the housing is an open end;

[0012] A tray, the tray is used to place a crystal resonator, and the tray comprises:

[0013] A frame, wherein a plurality of notches are formed on the frame, wherein rubber grooves are provided in the notches, and wherein the rubber grooves are used to store the crystal resonator;

[0014] A feeding assembly, the feeding assembly is arranged in the housing, and the feeding assembly comprises:

[0015] A chain, wherein at least two groups of chains are provided, both ends of the chain are provided with driving teeth, a driving rod is fixedly connected inside the driving teeth, both ends of the driving rod are rotatably connected to the inner wall of the shell, a connecting piece is arranged in an array on the chain, the connecting piece moves synchronously with the chain, a clamping block is fixedly connected to the connecting piece, a tray is placed between the clamping blocks, and a clamping plate is fixedly connected between the clamping block and the clamping block on the adjacent chain;

[0016] The ejection mechanism is arranged on the upper side of the shell and is used to push the empty tray out of the shell; the ejection mechanism includes:

[0017] A gear, wherein a ejection housing is provided on one side of the gear;

[0018] An ejection assembly, the ejection assembly is arranged on the ejection mechanism, and the ejection assembly is used to cooperate with the ejection mechanism to eject the crystal resonator in the tray groove; the ejection assembly includes:

[0019] A hollow rod, wherein an array of folding airbags is arranged on the hollow rod, wherein the folding airbags are arranged directly below the rubber groove, wherein an L-shaped rod is fixedly connected to the hollow rod, wherein an air pump is arranged on the ejection shell, wherein an air pipe is connected to the bottom of the folding airbag, wherein the air pipes are arranged in the hollow rod and the L-shaped rod, wherein an electromagnetic valve is arranged in the air pipe.

[0020] Preferably, a pulley is rotatably connected to the clamping block, the pulley is in contact with the tray, and a rubber layer is provided on the surface of the pulley.

[0021] Preferably, the gear is arranged at the bottom of the tray, tooth grooves are opened on both sides of the bottom of the tray, a connecting rod 1 is fixedly connected to the inner wall of the gear, the connecting rod 1 is rotatably connected to the ejection shell, and the gear is symmetrically arranged about the connecting rod 1.

[0022] Preferably, one end of the connecting rod is fixedly connected to bevel gear one, one side of the bevel gear one is meshed with bevel gear two, one side of the bevel gear two is fixedly connected to connecting rod two, the end of the connecting rod two away from bevel gear two is fixedly connected to roller one, a servo motor one is provided on the ejection shell, the end of the internal rotating shaft of the servo motor one is fixedly connected to roller two, and roller one and roller two are connected by a driving belt.

[0023] Preferably, a special-shaped rod is fixedly connected to the top of the ejection shell, two special-shaped rods are symmetrically arranged about the tray, round rods are fixedly connected between the special-shaped rods, scraper rods are arranged in an array on the round rods, and the scraper rods have the same number of rubber grooves transverse to the tray.

[0024] Preferably, pressure rollers are arranged in an array on the round rod, the number of the pressure rollers is equal to the number of the scraping rods, and the pressure rollers are rotatably connected to the round rod.

[0025] Preferably, roller three is provided at one end of the driving rod, roller four is provided on one side of roller three, a connecting belt is provided between roller three and roller four, servo motor two is provided at one end of roller four, and the end of the internal rotating shaft of servo motor two is fixedly connected to roller four.

[0026] The present invention has at least the following beneficial effects:

[0027] By opening the door of the placement machine's feeding bin, the operator can put the tray filled with crystal resonators between the clamps. After the placement machine is started, the suction cup system will take out the crystal resonators on the top tray, and then the push-out mechanism will push the top tray out of the shell. The drive rod drives the clamps on the chain to rotate, and then the tray moves up one station to complete the automatic replacement of the tray. This process can be repeated, thereby reducing the cycle of manual loading, effectively shortening downtime, and improving production efficiency.

[0028] When the suction cup moves to the top of the crystal resonator on the tray and contacts the surface of the crystal resonator, the ejector assembly takes out the crystal resonator and the suction cup from the bottom of the rubber groove. The use of the ejector assembly can effectively avoid excessive friction between the rubber groove and the crystal resonator, ensuring that the suction cup can smoothly suck out the crystal resonator.

[0029] It is worth noting that the tray is driven by the gear to move outward one station at a time, and the crystal resonator on the station can be taken out with the suction cup in cooperation with the ejection component. This process does not require manual operation, and the empty tray can be collected.

[0030] The gear is driven to rotate by a connecting rod, and the gear is meshed with a tooth groove at the bottom of the tray. The gear drives the tray to move out of the shell, so that the next tray full of crystal resonators can be moved up. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 It is a structural schematic diagram of another viewing angle of the present invention;

[0033] Figure 3 It is a side view structural schematic diagram of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of the launching mechanism of the present invention;

[0035] Figure 5 This is a structural schematic diagram of a connecting rod of the present invention;

[0036] Figure 6 This is a schematic diagram of the scraper structure of the present invention;

[0037] Figure 7 It is a schematic diagram of the structure of the ejection assembly of the present invention;

[0038] Figure 8 This is a structural schematic diagram of the servo motor 2 of the present invention;

[0039] Fig. 9 For the present invention Figure 3 A schematic diagram of the enlarged structure of part A.

[0040] In the figure: 10, shell; 20, feeding assembly; 21, chain; 22, driving teeth; 23, driving rod; 24, connecting piece; 25, clamping block; 26, clamping plate; 30, ejection mechanism; 40, ejection assembly; 251, pulley; 31, gear; 32, tooth groove; 33, ejection shell; 34, connecting rod one; 35, bevel gear one; 36, bevel gear two; 37, connecting rod two; 38, servo motor one; 51, special-shaped rod; 52, round rod; 53, scraper rod; 54, pressure roller; 41, hollow rod; 42, folding airbag; 43, L-shaped rod; 44, air pump; 45, air pipe; 233, servo motor two; 231, roller three; 232, roller four. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Embodiment 1: First, most of the existing loading methods are introduced. The existing manual loading tray operation is that the staff manually puts the tray containing components such as crystal resonators into the feeding position of the placement machine. The components in the tray are usually arranged in sequence, and the feeding system takes out the components one by one through the suction cup system and places them on the PCB pads. When the components in the tray are used up, the staff needs to take out the empty tray and replace it with a new tray.

[0043] See also Figure 1-9 The present invention provides a technical solution: a crystal resonator patch device, comprising:

[0044] A housing 10, wherein the housing 10 is disposed in the placement machine, and the top of the housing 10 is an open end, and the open end of the top of the housing 10 facilitates the suction cup to remove the crystal resonator on the tray at the top of the housing 10;

[0045] A tray, the tray is used to place a crystal resonator, and the tray comprises:

[0046] A frame, wherein a plurality of notches are formed on the frame, wherein rubber grooves are formed in the notches, wherein the rubber grooves are used to store the crystal resonator. By adopting a tray with rubber grooves, the friction between the crystal resonator and the rubber grooves can be increased, and thus, the crystal resonator is not easily displaced in the rubber grooves during handling or up and down transportation, thereby avoiding dislocation and making the suction of the suction cup more stable;

[0047] A feeding assembly 20, which is disposed in the housing 10, and includes:

[0048] The chain 21 is provided with at least two groups, and driving teeth 22 are provided at both ends of the chain 21. A driving rod 23 is fixedly connected inside the driving teeth 22. Both ends of the driving rod 23 are rotatably connected to the inner wall of the housing 10. Connectors 24 are arranged in an array on the chain 21. The connecting members 24 move synchronously with the chain 21. Clamping blocks 25 are fixedly connected to the connecting members 24. Trays are placed between the clamping blocks 25. Clamping plates 26 are fixedly connected between the clamping blocks 25 and the clamping blocks 25 on the adjacent chains 21.

[0049] It should be noted that by opening the door of the placement machine's feed bin, the operator can place a tray filled with crystal resonators between the clamps 25. After the placement machine is started, the suction cup system will take out the crystal resonators on the top tray, and then the ejection mechanism 30 will push the top tray out of the shell 10. The drive rod 23 drives the clamp 25 on the chain 21 to rotate, thereby moving the tray up one station to complete the automatic replacement of the tray. This process can be repeated, thereby reducing the cycle of manual loading, effectively shortening downtime, and improving production efficiency.

[0050] An ejection mechanism 30, which is disposed on the upper side of the housing 10 and is used to eject the empty tray out of the housing 10;

[0051] An ejection assembly 40, wherein the ejection assembly 40 is disposed on the ejection mechanism 30, and the ejection assembly 40 is used to cooperate with the ejection mechanism 30 to eject the crystal resonator in the tray groove;

[0052] It should be noted that when the suction cup moves to the top of the crystal resonator on the tray and contacts the surface of the crystal resonator, the ejection component 40 removes the crystal resonator together with the suction cup from the bottom of the rubber groove. The use of the ejection component 40 can effectively avoid excessive friction between the rubber groove and the crystal resonator, ensuring that the suction cup can smoothly suck out the crystal resonator.

[0053] Further Fig. 9 As shown, it is worth to explain in detail that the clamping block 25 is rotatably connected with a pulley 251, the pulley 251 is in contact with the tray, and a rubber layer is provided on the surface of the pulley 251;

[0054] It should be noted that when the tray is placed, the surface of the tray can slide on the pulley 251 , thereby reducing the friction on the surface of the tray and making it easier for the operator to insert the tray between the clamping blocks 25 .

[0055] Further Figure 4 and Figure 5 As shown, it is worth to explain in detail that the ejection mechanism 30 includes:

[0056] Gear 31, the gear 31 is arranged at the bottom of the tray, tooth grooves 32 are opened on both sides of the bottom of the tray, an ejection shell 33 is arranged on one side of the gear 31, a connecting rod 1 34 is fixedly connected to the inner wall of the gear 31, the connecting rod 1 34 is rotatably connected to the ejection shell 33, and the gear 31 is symmetrically arranged about the connecting rod 1 34;

[0057] It should be noted that the gear 31 is driven to rotate by the connecting rod 1 34, and the gear 31 is meshed with the tooth groove 32 at the bottom of the tray, and the gear 31 drives the tray to move out of the housing 10, so that the next tray full of crystal resonators can be moved up;

[0058] It is worth noting that each time the tray is moved outward one station by the gear 31, the crystal resonator on the station can be taken out in cooperation with the suction cup by cooperating with the ejection assembly 40. This process does not require manual operation and the empty tray can be collected.

[0059] Further Figure 4As shown, it is worth specifically explaining that the end of the connecting rod 1 34 is fixedly connected to a bevel gear 1 35, one side of the bevel gear 1 35 is meshed with a bevel gear 2 36, the bevel gear 1 35 and the bevel gear 2 36 are both rotatably connected to the ejection shell 33, one side of the bevel gear 2 36 is fixedly connected to a connecting rod 2 37, the end of the connecting rod 2 37 away from the bevel gear 2 36 is fixedly connected to a roller 1, the ejection shell 33 is provided with a servo motor 1 38, the end of the internal rotating shaft of the servo motor 1 38 is fixedly connected to the roller 2, and the rollers 1 and 2 are connected by a driving belt;

[0060] It should be noted that the servo motor 1 38 drives the roller 2 to rotate, the roller 2 drives the roller 1 to rotate through the driving belt, the roller 1 drives the bevel gear 2 36 to rotate through the connecting rod 2 37, and then drives the bevel gear 1 35 to rotate, the bevel gear 1 35 drives the gears 31 on both sides of the connecting rod 1 34 to rotate, and then drives the tray to move in the clamping block 25.

[0061] Further Figure 6 As shown, it is worth to explain in detail that the top of the ejection shell 33 is fixedly connected with a special-shaped rod 51, and two special-shaped rods 51 are symmetrically arranged about the tray, and a round rod 52 is fixedly connected between the special-shaped rods 51, and a scraper rod 53 is arranged in an array on the round rod 52, and the scraper rod 53 is equal to the number of the rubber grooves in the horizontal direction of the tray;

[0062] It should be noted that when the ejection assembly 40 ejects the crystal resonator in the rubber groove from the bottom of the tray, the rubber groove may be flipped out of the tray due to the action of force. When the tray is moved by the gear 31, the scraper rod 53 on the round rod 52 can effectively scrape the flipped rubber groove back into the tray to ensure that it is restored to its original state. This not only avoids damage to the rubber groove, but also ensures that it maintains good function in subsequent use, making it easy to reuse.

[0063] Further Figure 6 As shown, it is worth to explain in detail that the round rod 52 is provided with pressure rollers 54 in an array, the number of the pressure rollers 54 is equal to the number of the scraping rods 53, and the pressure rollers 54 are rotatably connected to the round rod 52;

[0064] It should be noted that when the tray is driven to move by the gear 31, the pressure roller 54 on the round rod 52 can directly act on the surface of the crystal resonator, and can press the crystal resonator with errors into the rubber groove to make its surface as parallel as possible, so as to facilitate the removal of the suction cup.

[0065] In summary: the crystal resonator patch device includes a shell 10, a tray, a feeding component 20, an ejection mechanism 30 and an ejection component 40, wherein the shell 10 is arranged in the patch machine, and the top open end is convenient for the suction cup to take out the crystal resonator. The rubber groove in the tray is used to store the crystal resonator, and the stability of the component is ensured by increasing the friction to avoid displacement. The feeding component 20 includes a chain 21 and a clamping block 25, which automatically drives the tray to move according to the work station, reduces the manual loading cycle and improves production efficiency. The ejection mechanism 30 drives the tray to move out through the gear 31, and the ejection component 40 cooperates with the suction cup to smoothly take out the crystal resonator. The clamping block 25 is provided with a pulley 251 to reduce friction and facilitate the placement of the tray. The gear 31 system drives the tray to move and combines with the ejection component 40 to complete the removal of the component, further improving the degree of automation, and the scraper rod 53 and the pressure roller 54 ensure that the rubber groove in the tray is restored to its original state, optimizing the removal process of the crystal resonator.

[0066] In the second embodiment, the ejection assembly 40 comprises:

[0067] A hollow rod 41, on which a folding airbag 42 is arranged in an array, and the folding airbag 42 is arranged just below the rubber groove, an L-shaped rod 43 is fixedly connected to the hollow rod 41, an air pump 44 is arranged on the ejection shell 33, and an air pipe 45 is connected to the bottom of the folding airbag 42, and the air pipe 45 is arranged in the hollow rod 41 and the L-shaped rod 43, and a solenoid valve is arranged in the air pipe 45;

[0068] It should be noted that when the suction cup needs to take out multiple crystal resonators from the tray, if it is necessary to take out multiple components in the same row at one time, the solenoid valve at the corresponding position can be opened to connect the air pipe 45 with the air pump 44. The air pump 44 transports the gas through the air pipe 45 to the folded airbag 42, thereby causing the folded airbag 42 to expand and lift up, thereby ejecting the crystal resonator at the corresponding position from the rubber groove. Subsequently, the suction cup cooperates with the ejection component 40 to take out these crystal resonators together, thereby realizing the simultaneous material removal of multiple crystal resonators. This process not only improves the material removal efficiency It can also ensure the synchronous removal of multiple components during multi-suction cup operation, further improving the automation level and operation efficiency of the production line. The top of the folding airbag 42 is a hard plane. By inflating the folding airbag 42, the crystal resonator in the rubber groove can be pushed up at an angle parallel to the suction cup mouth, thereby assisting the suction cup to remove the crystal resonator from the rubber groove with a certain pre-tightening force. At the same time, the folding airbag 42 pushes the crystal resonator upward in the horizontal direction to ensure that it will not be misaligned when it contacts the suction cup, so that the suction cup can more accurately drive the crystal resonator to complete the patch operation.

[0069] Further Figure 8As shown, it is worth specifically explaining that a third roller 231 is provided at one end of the driving rod 23, a fourth roller 232 is provided on one side of the third roller 231, a connecting belt is provided between the third roller 231 and the fourth roller 232, a servo motor 233 is provided at one end of the fourth roller 232, and the end of the internal rotating shaft of the servo motor 233 is fixedly connected to the fourth roller 232;

[0070] It should be noted that the servo motor 233 drives the roller 4 232 to rotate, and the roller 4 232 drives the roller 3 231 to rotate through the connecting belt, thereby driving the driving rod 23 to rotate, and the driving rod 23 drives the chain 21 to rotate through the driving teeth 22 at both ends.

[0071] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0072] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A crystal resonator patch device, characterized in that: include: A housing (10), the housing (10) being arranged in a chip mounter, and the top of the housing (10) being an open end; A tray, the tray is used to place a crystal resonator, and the tray comprises: A frame, wherein a plurality of notches are formed on the frame, wherein rubber grooves are provided in the notches, and wherein the rubber grooves are used to store the crystal resonator; A material supply assembly (20), wherein the material supply assembly (20) is arranged in the housing (10), and the material supply assembly (20) comprises: A chain (21), wherein at least two groups of the chain (21) are provided, both ends of the chain (21) are provided with driving teeth (22), a driving rod (23) is fixedly connected inside the driving teeth (22), both ends of the driving rod (23) are rotatably connected to the inner wall of the housing (10), a connecting piece (24) is arranged in an array on the chain (21), the connecting piece (24) moves synchronously with the chain (21), a clamping block (25) is fixedly connected to the connecting piece (24), a tray is placed between the clamping blocks (25), and a clamping plate (26) is fixedly connected between the clamping block (25) and the clamping block (25) on the adjacent chain (21); An ejection mechanism (30), the ejection mechanism (30) being arranged on the upper side of the shell (10), the ejection mechanism (30) being used to eject the empty tray out of the shell (10); the ejection mechanism (30) comprising: A gear (31), wherein an ejection housing (33) is provided on one side of the gear (31); An ejection assembly (40), the ejection assembly (40) being arranged on the ejection mechanism (30), the ejection assembly (40) being used to cooperate with the ejection mechanism (30) to eject the crystal resonator in the tray groove, the ejection assembly (40) comprising: A hollow rod (41), wherein an array of folded airbags (42) are arranged on the hollow rod (41), wherein the top plane of the folded airbags (42) is flush with the bottom of the rubber groove, wherein the folded airbags (42) are arranged directly below the rubber groove, and wherein the folded airbags (42) are used to lift up the crystal resonator in the rubber groove at an angle parallel to the suction cup opening, wherein an L-shaped rod (43) is fixedly connected to the hollow rod (41), and an air pump (44) is arranged on the ejection shell (33), wherein the bottom of the folded airbags (42) is connected to an air pipe (45), wherein the air pipe (45) is arranged in the hollow rod (41) and the L-shaped rod (43), and wherein an electromagnetic valve is arranged in the air pipe (45).

2. A crystal resonator patch device according to claim 1, characterized in that: The clamping block (25) is rotatably connected to a pulley (251), the pulley (251) is in contact with the tray, and a rubber layer is provided on the surface of the pulley (251).

3. A crystal resonator patch device according to any one of claims 1 or 2, characterized in that: The gear (31) is arranged at the bottom of the tray, and tooth grooves (32) are provided on both sides of the bottom of the tray. A connecting rod (34) is fixedly connected to the inner wall of the gear (31), and the connecting rod (34) is rotatably connected to the ejection shell (33). The gear (31) is symmetrically arranged with respect to the connecting rod (34).

4. A crystal resonator patch device according to claim 3, characterized in that: The end of the connecting rod 1 (34) is fixedly connected to a bevel gear 1 (35), one side of the bevel gear 1 (35) is meshed with a bevel gear 2 (36), one side of the bevel gear 2 (36) is fixedly connected to a connecting rod 2 (37), one end of the connecting rod 2 (37) away from the bevel gear 2 (36) is fixedly connected to a roller 1, a servo motor 1 (38) is provided on the ejection housing (33), the end of the internal rotating shaft of the servo motor 1 (38) is fixedly connected to the roller 2, and the rollers 1 and 2 are connected via a driving belt.

5. A crystal resonator patch device according to claim 4, characterized in that: A special-shaped rod (51) is fixedly connected to the top of the ejection shell (33), two special-shaped rods (51) are symmetrically arranged about the tray, a round rod (52) is fixedly connected between the special-shaped rods (51), and scraping rods (53) are arranged in an array on the round rods (52), and the scraping rods (53) have the same number as the rubber grooves in the transverse direction of the tray.

6. A crystal resonator patch device according to claim 5, characterized in that: The round rod (52) is provided with pressure rollers (54) in an array, the number of the pressure rollers (54) being equal to the number of the scraping rods (53), and the pressure rollers (54) are rotatably connected to the round rod (52).

7. The crystal resonator patch device according to claim 1, characterized in that: A third roller (231) is disposed at one end of the driving rod (23), a fourth roller (232) is disposed at one side of the third roller (231), a connecting belt is disposed between the third roller (231) and the fourth roller (232), a servo motor (233) is disposed at one end of the fourth roller (232), and an end of an internal rotating shaft of the servo motor (233) is fixedly connected to the fourth roller (232).

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