Binding equipment for wood

By designing automatic bundling equipment, the automatic limit fixation and release of wood is achieved by using telescopic push rods and limit pressure plates, the problem of low manual limit fixation efficiency in the prior art is solved and the efficiency of wood bundling processing is improved.

CN222347378UActive Publication Date: 2025-01-14HUBEI YISEN WOOD IND CO LTD
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Patent Information

Application Number
CN202420398532.4
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2024-02-29
Publication Date
2025-01-14
Estimated Expiration
2034-02-28

AI Technical Summary

Technical Problem

During use, existing wood bundling equipment requires users to manually fix the limits, resulting in inefficiency and inconvenience, and cannot fully meet the usage needs.

Method used

An automatic bundling device is designed, including an automatic bundling machine body, a walking wheel, a U-shaped gantry and a limit module. The automatic limit fixation and release of wood through telescopic push rods and limit pressure plates is achieved, and the efficiency of bundling processing is improved.

Benefits of technology

It realizes rapid and efficient limit fixation and removal of wood, improves bundling processing efficiency, simplifies the use process, and meets higher usage needs.

✦ Generated by Eureka AI based on patent content.

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Abstract

The utility model provides binding equipment for wood, which comprises an automatic binding machine body, walking wheels arranged at the bottom of the automatic binding machine body, a U-shaped portal frame arranged at the top of the automatic binding machine body in the left-right direction, and a limiting module comprising a first fixing frame arranged at the front end of the top of the automatic binding machine body in the left-right direction, and a second fixing frame arranged at the front end of the top of the automatic binding machine body in the left-right direction. A first telescopic push rod, a first limiting pressing plate, a second telescopic push rod, a second limiting pressing plate, a second fixing frame, a third telescopic push rod, a third limiting pressing plate, a fourth telescopic push rod and a fourth limiting pressing plate. According to the bundling equipment for the wood, the basic requirement for bundling treatment of the wood can be met, the wood to be bundled can be automatically limited and fixed, limiting and fixing of the bundled wood can be automatically relieved, and therefore the efficiency of bundling processing of the wood is improved.
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Description

Technical Field

[0001] The utility model belongs to the technical field of wood bundling processing, in particular to a wood bundling device. Background Art

[0002] In the process of processing wood, it is necessary to bundle the wood. Although the existing wood bundling equipment can meet the basic needs of automatic wood bundling, it often requires users to spend time and effort to limit and fix the wood during use, which not only brings great inconvenience to people's use, but also affects the overall efficiency of wood bundling, and cannot fully meet people's use needs. Utility Model Content

[0003] In view of this, the utility model aims to solve the shortcomings of the prior art and provide a bundling device for wood, which can not only meet the basic needs of bundling wood, but also automatically limit and fix the wood to be bundled and automatically release the limit and fixation of the wood that has been bundled, thereby improving the efficiency of bundling wood.

[0004] In order to solve the above technical problems, the technical solution adopted by the utility model is: a wood bundling device, comprising an automatic bundling machine body, a walking wheel is arranged at the bottom of the automatic bundling machine body, a U-shaped door frame at the top of the automatic bundling machine body is arranged along the left and right directions, a limiting module for limiting and fixing the wood is arranged at the top of the automatic bundling machine body, the limiting module comprises a first fixing frame arranged at the front end of the top of the automatic bundling machine body along the left and right directions, first telescopic push rods are respectively arranged laterally at the rear sides of the left and right side ends of the first fixing frame, and first telescopic push rods are respectively arranged at the ends of the output shafts of the two first telescopic push rods. A limiting pressure plate, a second telescopic push rod located in front of the first telescopic push rod is vertically arranged on the top of the first fixed frame, a second limiting pressure plate is arranged at the lower end of the output shaft of the second telescopic push rod, a second fixed frame is also arranged in the left and right directions at the top rear end of the automatic strapping machine body, third telescopic push rods are respectively arranged laterally at the front ends of the left and right sides of the second fixed frame, third limiting pressure plates are respectively arranged at the ends of the output shafts of the two third telescopic push rods, a fourth telescopic push rod located at the rear side of the third telescopic push rod is also vertically arranged on the top of the second fixed frame, and a fourth limiting pressure plate is arranged at the lower end of the output shaft of the fourth telescopic push rod.

[0005] As a further improvement of the utility model, first guide slots with openings at both ends and adapted to the second limit pressure plate are vertically arranged on the inner side walls of the left and right side ends of the first fixing frame, and first guide slide blocks adapted to the corresponding first guide slots are respectively arranged at the left and right side ends of the second limit pressure plate. The spacing between the top of the first guide slot and the top bottom wall of the first fixing frame is greater than the thickness of the first guide slide block, and the spacing between the bottom of the first guide slot and the bottom of the first fixing frame is greater than the thickness of the first guide slide block.

[0006] As a further improvement of the utility model, second guide slots with openings at both ends and adapted to the fourth limit pressure plate are vertically arranged on the inner side walls of the left and right side ends of the first fixed frame, and second guide slide blocks adapted to the corresponding second guide slots are respectively arranged on the left and right side ends of the fourth limit pressure plate. The spacing between the top of the first guide slot and the top bottom wall of the first fixed frame is greater than the thickness of the first guide slide block, and the spacing between the bottom of the first guide slot and the bottom of the first fixed frame is greater than the thickness of the first guide slide block.

[0007] As a further improvement of the utility model, the cross-sections of the sliding hole of the first guide sliding groove and the first guide sliding block are T-shaped, and the cross-sections of the sliding hole of the second guide sliding groove and the second guide sliding block are T-shaped.

[0008] As a further improvement of the utility model, the first limiting pressure plate is also provided with a first connecting tube which is clamped and fixed with the output shaft of the first telescopic push rod, the first connecting tube is also provided with a first connecting bolt for threadedly fixing the output shaft of the first telescopic push rod, and the output shaft of the first telescopic push rod is provided with a first threaded connecting hole which is compatible with the first connecting bolt.

[0009] As a further improvement of the utility model, the second limiting pressure plate is also provided with a second connecting tube which is clamped and fixed with the output shaft of the second telescopic push rod, the second connecting tube is also provided with a second connecting bolt for threadedly fixing the output shaft of the second telescopic push rod, and the output shaft of the second telescopic push rod is provided with a second threaded connecting hole which is compatible with the second connecting bolt.

[0010] As a further improvement of the utility model, the third limiting pressure plate is also provided with a third connecting tube which is clamped and fixed with the output shaft of the third telescopic push rod; the third connecting tube is also provided with a third connecting bolt for threadedly fixing the output shaft of the third telescopic push rod; the output shaft of the third telescopic push rod is provided with a third threaded connecting hole which is compatible with the third connecting bolt.

[0011] As a further improvement of the utility model, the fourth limiting pressure plate is also provided with a fourth connecting tube which is clamped and fixed with the output shaft of the fourth telescopic push rod, the fourth connecting tube is also provided with a fourth connecting bolt for threadedly fixing the output shaft of the fourth telescopic push rod, and the output shaft of the fourth telescopic push rod is provided with a fourth threaded connecting hole which is compatible with the fourth connecting bolt.

[0012] Compared with the prior art, the beneficial effects of the utility model are as follows:

[0013] First, after placing the bundled wood on the top of the automatic strapping machine, the front and rear parts of the wood at the strapping position can be laterally squeezed and fixed by the two first telescopic push rods, the two first limit pressing plates, the two third telescopic push rods, and the two third limit pressing plates. Then, the front and rear parts of the wood at the strapping position can be vertically squeezed and fixed by the second telescopic push rod, the second limit pressing plate, the fourth telescopic push rod, and the fourth limit pressing plate, so as to quickly and efficiently achieve the limit fixation of the wood to be bundled, and then the automatic strapping machine can be used to bundle the wood, and then the two first telescopic push rods drive the two first limit pressing plates to reset, the second telescopic push rod drives the second limit pressing plate to reset, the two third telescopic push rods drive the two third limit pressing plates to reset, and the fourth telescopic push rod drives the fourth limit pressing plate to reset, so as to release the limit fixation of the bundled wood, and then the bundled wood can be taken away from the top of the automatic strapping machine.

[0014] Secondly, because the cross-sections of the slide hole of the first guide slot and the first guide slider are T-shaped, the first guide slider can be prevented from being laterally offset relative to the first guide slot, thereby guiding the second limit pressure plate more smoothly.

[0015] Thirdly, because the cross-sections of the slide hole of the second guide slot and the second guide slider are T-shaped, the second guide slider can be prevented from being laterally offset relative to the second guide slider, thereby guiding the fourth limiting pressure plate more smoothly.

[0016] Fourthly, through the cooperation of the first connecting tube, the first connecting bolt and the first threaded connecting hole, the output shaft of the first telescopic push rod and the first limiting pressure plate can be flexibly fixed; through the cooperation of the second connecting tube, the second connecting bolt and the second threaded connecting hole, the output shaft of the second telescopic push rod and the second limiting pressure plate can be flexibly fixed; through the cooperation of the third connecting tube, the third connecting bolt and the third threaded connecting hole, the output shaft of the third telescopic push rod and the third limiting pressure plate can be flexibly fixed; through the cooperation of the fourth connecting tube, the fourth connecting bolt and the fourth threaded connecting hole, the output shaft of the fourth telescopic push rod and the fourth limiting pressure plate can be flexibly fixed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0018] Figure 1 It is a front structural schematic diagram of the utility model;

[0019] Figure 2 It is a rear view structural schematic diagram of the utility model;

[0020] Figure 3 It is a structural schematic diagram of the first fixing frame, the first telescopic push rod, the first limiting pressure plate, the second telescopic push rod, the second limiting pressure plate, the first connecting tube, the first connecting bolt, the second connecting tube, the second connecting bolt, the first guide slide groove, and the first guide slide block of the utility model;

[0021] Figure 4 It is a structural schematic diagram of the second fixing frame, the third telescopic push rod, the first limiting pressure plate, the fourth telescopic push rod, the fourth limiting pressure plate, the third connecting tube, the third connecting bolt, the fourth connecting tube, the fourth connecting bolt, the second guide slide groove, and the second guide slide block of the utility model.

[0022] In the figure: 101, automatic strapping machine body; 102, walking wheel; 201, first fixed frame; 202, first telescopic push rod; 203, first limit pressure plate; 204, second telescopic push rod; 205, second limit pressure plate; 206, second fixed frame; 207, third telescopic push rod; 208, third limit pressure plate; 209, fourth telescopic push rod; 210, fourth limit pressure plate; 211, first connecting tube; 212, first connecting bolt; 213, second connecting tube; 214, second connecting bolt; 215, third connecting tube; 216, third connecting bolt; 217, fourth connecting tube; 218, fourth connecting bolt; 301, first guide slide; 302, first guide slider; 303, second guide slide; 304, second guide slider. DETAILED DESCRIPTION

[0023] In order to better understand the present invention, the content of the present invention is further clearly described below in conjunction with the embodiments, but the protection content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0024] like Figure 1 , 2As shown in , 3 and 4, a wood bundling device comprises an automatic bundling machine body 101, a walking wheel 102 is arranged at the bottom of the automatic bundling machine body 101, a U-shaped door frame is arranged along the left-right direction at the top of the automatic bundling machine body 101, a limiting module for limiting and fixing the wood is arranged at the top of the automatic bundling machine body 101, the limiting module comprises a first fixing frame 201 arranged at the front end of the top of the automatic bundling machine body 101 along the left-right direction, first telescopic push rods 202 are respectively arranged laterally at the rear sides of the left and right side ends of the first fixing frame 201, first limiting pressing plates 203 are respectively arranged at the ends of the output shafts of the two first telescopic push rods 202, and the top of the first fixing frame 201 A second telescopic push rod 204 is also vertically arranged in front of the first telescopic push rod 202, and a second limiting pressing plate 205 is arranged at the lower end of the output shaft of the second telescopic push rod 204. A second fixing frame 206 is also arranged in the left and right directions at the top rear end of the automatic strapping machine body 101, and third telescopic push rods 207 are respectively arranged laterally at the front ends of the left and right side ends of the second fixing frame 206, and third limiting pressing plates 208 are respectively arranged at the ends of the output shafts of the two third telescopic push rods 207. A fourth telescopic push rod 209 is also vertically arranged on the top of the second fixing frame 206 and is located at the rear side of the third telescopic push rod 207, and a fourth limiting pressing plate 210 is arranged at the lower end of the output shaft of the fourth telescopic push rod 209.

[0025] After placing the bundled wood on the top of the automatic strapping machine, the output shafts of the two first telescopic push rods 202 can be extended by a certain length first, so that the two first limit pressing plates 203 can laterally squeeze and fix the front part of the wood at the strapping position; the output shafts of the two third telescopic push rods can be extended by a certain length, so that the two third limit pressing plates 208 can laterally squeeze and fix the rear part of the wood at the strapping position; the output shaft of the second telescopic push rod 204 can be extended downward by a certain length, so that the second limit pressing plate 205 can vertically squeeze and fix the front part of the wood at the strapping position; the output shaft of the fourth telescopic push rod 209 can be extended downward by a certain length, so that the fourth limit pressing plate 210 can vertically squeeze and fix the front part of the wood at the strapping position; thereby, the limit fixation of the wood to be strapped can be achieved quickly and efficiently, and then the automatic strapping machine can be used to strap the wood.

[0026] Then, the two first telescopic push rods 202 drive the two first limit pressing plates 203 to reset, the second telescopic push rod 204 drives the second limit pressing plate 205 to reset, the two third telescopic push rods 207 drive the two third limit pressing plates 208 to reset, and the fourth telescopic push rod 209 drives the fourth limit pressing plate 210 to reset, so as to release the limit fixation of the bundled wood, and then the bundled wood can be taken away from the top of the automatic strapping machine.

[0027] According to another embodiment of the present invention, Figure 1 , 3 As shown, the first guide slots 301 with both upper and lower ends open and matched with the second limiting pressure plate 205 are also vertically arranged on the inner side walls of the left and right side ends of the first fixing frame 201, and the first guide sliders 302 matched with the corresponding first guide slots 301 are respectively arranged on the left and right side ends of the second limiting pressure plate 205. The cross-sections of the slide hole of the first guide slot 301 and the first guide slider 302 are T-shaped. Through the cooperation of the first guide slot 301 and the first guide slider 302, the second limiting pressure plate 205 can be moved vertically more smoothly. Because the cross-sections of the slide hole of the first guide slot 301 and the first guide slider 302 are T-shaped, the first guide slider 302 can be prevented from being laterally offset relative to the first guide slot 301, thereby guiding the second limiting pressure plate 205 more smoothly. The distance between the top of the first guide slot 301 and the top and bottom walls of the first fixing frame 201 is greater than the thickness of the first guide slider 302, and the distance between the bottom of the first guide slot 301 and the bottom of the first fixing frame 201 is greater than the thickness of the first guide slider 302. The distance between the top of the second guide slot 303 and the top and bottom walls of the second fixing frame 206 is greater than the thickness of the second guide slider 304, and the distance between the bottom of the second guide slot 303 and the bottom of the second fixing frame 206 is greater than the thickness of the second guide slider 304.

[0028] According to another embodiment of the present invention, Figure 2 , 4 As shown, the inner side walls of the left and right side ends of the first fixing frame 201 are also vertically provided with second guide slots 303 with both upper and lower ends opened and adapted to the fourth limiting pressure plate 210, and the left and right side ends of the fourth limiting pressure plate 210 are respectively provided with second guide sliders 304 adapted to the corresponding second guide slots 303. Through the cooperation of the second guide slots 303 and the second guide sliders 304, the fourth limiting pressure plate 210 can be moved vertically more smoothly. The sliding hole of the second guide slot 303 and the cross section of the second guide slider 304 are T-shaped. Because the sliding hole of the second guide slot 303 and the cross section of the second guide slider 304 are T-shaped, the second guide slider 304 can be prevented from being laterally offset relative to the second guide slider 304, thereby guiding the fourth limiting pressure plate 210 more smoothly. The distance between the top of the second guide slot 303 and the top bottom wall of the second fixing frame 206 is greater than the thickness of the second guide slider 304 , and the distance between the bottom of the second guide slot 303 and the bottom of the second fixing frame 206 is greater than the thickness of the second guide slider 304 .

[0029] According to another embodiment of the present invention, Figure 3As shown, the first limiting pressure plate 203 is also provided with a first connecting tube 211 which is clamped and fixed with the output shaft of the first telescopic push rod 202, and the first connecting tube 211 is also provided with a first connecting bolt 212 for threadedly fixing the output shaft of the first telescopic push rod 202, and the output shaft of the first telescopic push rod 202 is provided with a first threaded connecting hole which is compatible with the first connecting bolt 212.

[0030] like Figure 3 As shown, the second limiting pressure plate 205 is also provided with a second connecting tube 213 which is clamped and fixed with the output shaft of the second telescopic push rod 204, and the second connecting tube 213 is also provided with a second connecting bolt 214 for threadedly fixing the output shaft of the second telescopic push rod 204, and the output shaft of the second telescopic push rod 204 is provided with a second threaded connecting hole which is compatible with the second connecting bolt 214.

[0031] like Figure 4 As shown, the third limiting pressure plate 208 is also provided with a third connecting cylinder 215 which is clamped and fixed with the output shaft of the third telescopic push rod 207. The third connecting cylinder 215 is also provided with a third connecting bolt 216 for threadedly fixing the output shaft of the third telescopic push rod 207. The output shaft of the third telescopic push rod 207 is provided with a third threaded connecting hole which is compatible with the third connecting bolt 216.

[0032] like Figure 4 As shown, the fourth limiting pressure plate 210 is also provided with a fourth connecting tube 217 which is clamped and fixed with the output shaft of the fourth telescopic push rod 209, and the fourth connecting tube 217 is also provided with a fourth connecting bolt 218 for threadedly fixing the output shaft of the fourth telescopic push rod 209, and the output shaft of the fourth telescopic push rod 209 is provided with a fourth threaded connecting hole which is compatible with the fourth connecting bolt 218.

[0033] The output shaft of the first telescopic push rod 202 can be flexibly fixed to the first limit plate 203 by simply clamping and fixing the first connecting tube 211 with the output shaft of the first telescopic push rod 202, and then passing the first connecting bolt 212 through the side wall of the first connecting tube 211 and screwing and fixing it with the first threaded connecting hole; the output shaft of the second telescopic push rod 204 can be flexibly fixed to the second limit plate 205 by simply clamping and fixing the second connecting tube 213 with the output shaft of the second telescopic push rod 204, and then passing the second connecting bolt 214 through the side wall of the first connecting tube 211 and screwing and fixing it with the second threaded connecting hole; The output shaft of the third telescopic push rod 207 and the third limit pressing plate 208 can be flexibly fixed by only making the third connecting cylinder 215 and the output shaft of the third telescopic push rod 207 clamped and fixed, and then making the third connecting bolt 216 pass through the side wall of the third connecting cylinder 215 and screw-fixed with the second threaded connection hole, so as to realize the flexible fixation of the output shaft of the third telescopic push rod 207 and the third limit pressing plate 208; the output shaft of the fourth telescopic push rod 209 and the fourth limit pressing plate 210 can be flexibly fixed by only making the fourth connecting cylinder 217 and the output shaft of the fourth telescopic push rod 209 clamped and fixed, and then making the fourth connecting bolt 218 pass through the side wall of the fourth connecting cylinder 217 and screw-fixed with the second threaded connection hole. Therefore, the worn first limit pressing plate 203 and the third limit pressing plate 208 can be conveniently replaced, the worn second limit pressing plate 205 and the first guide slider 302 can be conveniently replaced together, and the worn fourth limit pressing plate 210 and the second guide slider 304 can be conveniently replaced together.

[0034] The above are preferred implementations of the present utility model. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present utility model. These improvements and modifications should also be regarded as the protection scope of the present utility model.

Claims

1. A wood bundling device, comprising an automatic bundling machine body (101), a running wheel (102) is arranged at the bottom of the automatic bundling machine body (101), a U-shaped door frame at the top of the automatic bundling machine body (101) is arranged in the left and right directions, and a limiting module for limiting and fixing the wood is arranged at the top of the automatic bundling machine body (101), characterized in that: The limiting module comprises a first fixing frame (201) arranged at the front end of the top of the automatic strapping machine body (101) in the left-right direction, first telescopic push rods (202) are respectively arranged transversely on the rear sides of the left and right side ends of the first fixing frame (201), the ends of the output shafts of the two first telescopic push rods (202) are respectively provided with first limiting pressure plates (203), and a second telescopic push rod (204) located in front of the first telescopic push rod (202) is also vertically arranged on the top of the first fixing frame (201), and a second limiting pressure plate (203) is arranged at the lower end of the output shaft of the second telescopic push rod (204). 5), a second fixing frame (206) is also arranged at the top rear end of the automatic strapping machine body (101) along the left-right direction, and third telescopic push rods (207) are respectively arranged transversely at the front ends of the left and right side ends of the second fixing frame (206), and the ends of the output shafts of the two third telescopic push rods (207) are respectively arranged with third limiting pressure plates (208), and a fourth telescopic push rod (209) is also vertically arranged at the top of the second fixing frame (206) and is located at the rear side of the third telescopic push rod (207), and a fourth limiting pressure plate (210) is arranged at the lower end of the output shaft of the fourth telescopic push rod (209).

2. The wood bundling device according to claim 1, characterized in that: The first guide slot (301) with openings at both ends and matched with the second limiting pressure plate (205) is also vertically arranged on the inner side walls of the left and right side ends of the first fixed frame (201), and the left and right side ends of the second limiting pressure plate (205) are respectively provided with first guide slide blocks (302) matched with the corresponding first guide slot (301), and the distance between the top of the first guide slot (301) and the top bottom wall of the first fixed frame (201) is greater than the thickness of the first guide slide block (302), and the distance between the bottom of the first guide slot (301) and the bottom of the first fixed frame (201) is greater than the thickness of the first guide slide block (302).

3. The wood bundling device according to claim 2, characterized in that: A second guide slot (303) with openings at both ends and matched with the fourth limiting pressure plate (210) is also vertically arranged on the inner side walls of the left and right side ends of the first fixed frame (201); the left and right side ends of the fourth limiting pressure plate (210) are respectively provided with a second guide slider (304) matched with the corresponding second guide slot (303); the distance between the top of the second guide slot (303) and the top and bottom walls of the second fixed frame (206) is greater than the thickness of the second guide slider (304); the distance between the bottom of the second guide slot (303) and the bottom of the second fixed frame (206) is greater than the thickness of the second guide slider (304).

4. The wood bundling device according to claim 3, characterized in that: The cross-sections of the sliding hole of the first guide sliding groove (301) and the first guide sliding block (302) are T-shaped, and the cross-sections of the sliding hole of the second guide sliding groove (303) and the second guide sliding block (304) are T-shaped.

5. The wood bundling device according to claim 4, characterized in that: The first limiting pressure plate (203) is also provided with a first connecting tube (211) which is clamped and fixed to the output shaft of the first telescopic push rod (202); the first connecting tube (211) is also provided with a first connecting bolt (212) for threadedly fixing the output shaft of the first telescopic push rod (202); and the output shaft of the first telescopic push rod (202) is provided with a first threaded connecting hole which is compatible with the first connecting bolt (212).

6. The wood bundling device according to claim 5, characterized in that: The second limiting pressure plate (205) is also provided with a second connecting tube (213) which is clamped and fixed to the output shaft of the second telescopic push rod (204); the second connecting tube (213) is also provided with a second connecting bolt (214) for threadedly fixing the output shaft of the second telescopic push rod (204); and the output shaft of the second telescopic push rod (204) is provided with a second threaded connecting hole which is compatible with the second connecting bolt (214).

7. The wood bundling device according to claim 6, characterized in that: The third limiting pressure plate (208) is also provided with a third connecting tube (215) which is clamped and fixed to the output shaft of the third telescopic push rod (207); the third connecting tube (215) is also provided with a third connecting bolt (216) for threading and fixing the output shaft of the third telescopic push rod (207); and the output shaft of the third telescopic push rod (207) is provided with a third threaded connecting hole which is compatible with the third connecting bolt (216).

8. The wood bundling device according to claim 7, characterized in that: The fourth limiting pressure plate (210) is also provided with a fourth connecting tube (217) which is clamped and fixed to the output shaft of the fourth telescopic push rod (209); the fourth connecting tube (217) is also provided with a fourth connecting bolt (218) for threadedly fixing the output shaft of the fourth telescopic push rod (209); and the output shaft of the fourth telescopic push rod (209) is provided with a fourth threaded connecting hole which is compatible with the fourth connecting bolt (218).