Anti-fracture structure of injection molding machine pull rod

Abstract

The application discloses a kind of anti-fracture structure of injection molding machine pull rod, including cylinder, piston and pull rod, characterized in that the front end of pull rod is provided with external thread section, pull rod nut is screw-connected and installed on external thread section, piston is sleeved on pull rod, piston is fixedly connected with pull rod nut, cylinder has inner cavity for piston to move forward and backward, piston includes push part and guide part, which are coaxially arranged from front to back, the outer diameter of push part is greater than that of guide part, push part is movably arranged in inner cavity, the front end of push part protrudes out of cylinder, and the front end surface of push part is in close contact with the rear end surface of pull rod nut, a guide cavity is connected to the rear of inner cavity, the guide cavity is coaxial with pull rod, and the guide part is movably inserted into the guide cavity.The advantage is simple structure, low cost, which can effectively prevent the pull rod of injection molding machine from breaking.

Description

Technical Field

[0001] The invention relates to a pull rod of an injection molding machine, in particular to an anti-breaking structure of the pull rod of an injection molding machine. Background Art

[0002] The injection molding machine tie rod, also known as the clamping tie rod or the coring rod, is an accessory component used to guide the movable platen and lock it to the fixed platen in the injection molding machine. It plays a very important role in the injection molding process of the injection molding machine.

[0003] Chinese invention patent No. 201611248433.4 discloses a tie rod for an injection molding machine, comprising a tie rod body, a stressed externally threaded section disposed in the middle of the tie rod body, a piston sleeved on the tie rod body and threadably connected to the externally threaded section, and a piston locating member disposed between the tie rod body and the piston to position the piston. When the tie rod of the above structure is used in an injection molding machine, the movable mold plate will slightly deform during mold closing, causing the tie rod body and the piston to also be compressed and deformed during mold closing. In order to thread the piston onto the tie rod body, the tie rod of the above structure is provided with an externally threaded section on the tie rod body. When the tie rod body and the piston are compressed and deformed, stress is concentrated on the externally threaded section. The externally threaded section is subjected to concentrated stress for a long time and is prone to breakage, seriously affecting the service life of the tie rod of the injection molding machine.

[0004] Based on the above problems, the Chinese invention patent with patent number 201721434877.7 discloses an integrated injection molding machine tie rod, that is, the piston and the tie rod are made into an integral part, thereby reducing the risk of the tie rod breaking. The advantage of this type of tie rod is that it eliminates the risk of the threaded section of the above-mentioned split tie rod breaking, but this type of tie rod still has the risk of breaking near the arc section, because the tie rod will still produce stress deformation that causes breaking after being deformed by the overload, and thus the risk of the tie rod breaking still exists. In addition, this type of tie rod usually needs to use special-shaped forging materials. For large-tonnage injection molding machines, this type of material is less common in the market, so it is more expensive than ordinary standard cylindrical blanks, and the manufacturing time is also longer. For large-tonnage injection molding machines, the difference in material costs for the four tie rods is at least tens of thousands, resulting in higher manufacturing costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an anti-breaking structure for a tie rod of an injection molding machine, which has a simple structure and low cost, can effectively prevent the tie rod of the injection molding machine from breaking, and ensure its service life.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] The cam is fixedly mounted on the front end of the piston rod and is provided with a push rod nut, the push rod nut being fixedly mounted on the front end of the piston rod and the piston being connected to the piston rod nut.

[0008] The cylinder body includes a cylinder barrel, the front end of which is recessed rearward to form the inner cavity, the rear end of which is provided with the guide cavity, and a cylinder head mounted on the front end of the cylinder barrel. The cylinder head has an extension cavity extending front to back through which the front end of the pusher portion extends. The front end of the pusher portion can movably pass through the extension cavity so that the front end of the pusher portion is in contact with the rear end of the tie rod nut. The cylinder body has a simple structure and low manufacturing cost.

[0009] The cylinder body has two oil inlets, and the cylinder head includes a front cover portion and a rear mounting portion, arranged sequentially from front to rear. The front cover portion is provided to seal the front end of the cylinder barrel, while the rear mounting portion extends into and is sealed within the inner cavity. A front sealing member is provided between the push portion and the extension cavity, and a rear sealing member is provided between the guide portion and the guide cavity. This structure ensures stable operation of the cylinder body. Sealing rings are typically used for the front and rear sealing members, resulting in a simple structure, easy installation, and low cost.

[0010] An annular limit guide protrudes from the rear outer wall of the pusher portion. The guide cooperates with the inner cavity and is movably disposed therein. A sealing structure is provided between the guide and the inner cavity. The guide cooperates with the rear mounting portion to limit the piston's travel. The guide also cooperates with the inner cavity to guide the piston's movement, ensuring that the force applied to the pull rod and piston remains consistent.

[0011] The front end of the pusher is recessed and provided with a positioning groove, and the rear end of the tie rod nut is protruding and provided with an annular positioning portion that cooperates with the positioning groove. The annular positioning portion is embedded in the positioning groove. The cooperation between the positioning groove and the annular positioning portion effectively ensures that the front end of the pusher and the rear end of the tie rod nut can be stably and securely mounted.

[0012] The annular positioning portion is an annular truncated cone with an outer diameter gradually decreasing from front to back, which is convenient for installation.

[0013] The pull rod is provided with an anti-rotation mechanism for preventing the pull rod nut from rotating relative to the pull rod. The anti-rotation mechanism can effectively prevent the pull rod nut from rotating relative to the pull rod when subjected to force.

[0014] The anti-rotation mechanism includes a nut end cap fixedly mounted on the front end face of the pull rod, the rear end face of the nut end cap being fitted against the front end face of the pull rod, and the nut end cap being fixedly connected to the pull rod nut via a connecting member. The anti-rotation mechanism has a simple structure, low cost, and good anti-rotation effect.

[0015] The front end surface of the tie rod nut is provided with a connecting screw hole, and the nut end cap is provided with a connecting hole that passes through the front and back and matches the connecting screw hole. The connecting member is a connecting screw or connecting bolt that matches the connecting screw hole. The connecting screw or connecting bolt passes through the connecting hole and is screwed into the connecting screw hole at the corresponding position to achieve the fixed installation between the nut end cap and the tie rod nut. The structure is simple, the cost is low, and the installation and disassembly are convenient.

[0016] The rear end face of the pull rod nut and the front end face of the push portion are flat end faces, ensuring that the two are stably fitted and that the force transmitted from the piston to the pull rod is in the same direction.

[0017] The pull rod nut and the piston are fixedly connected by bolts or screws.

[0018] Compared with the prior art, the advantages of the present invention are: the pull rod is installed on it through the piston sleeve and cooperates with the cylinder body to form a support guide for the pull rod, the guide section on the piston cooperates with the guide cavity on the cylinder body to form a support guide for the piston and the pull rod, and at the same time, the front end face of the piston push part is in surface contact with the rear end face of the pull rod nut installed on the external threaded section of the pull rod, ensuring that the force transmitted to the pull rod by the piston is in the same direction and will not cause deviation, effectively avoiding the pull rod from breaking due to unbalanced load, simple structure, low manufacturing cost, and more effective anti-breakage effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is a schematic diagram of the overall cross-sectional structure of the present invention;

[0020] Figure 2 Schematic diagram of the cross-sectional structure of the piston in the present invention;

[0021] Figure 3 It is a schematic diagram of the decomposition structure of the present invention;

[0022] Figure 4 It is a schematic cross-sectional structural diagram of the cylinder body in the present invention. DETAILED DESCRIPTION

[0023] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0024] As shown in the figure, an anti-breaking structure of the tie rod of an injection molding machine includes a cylinder body 1, a piston 2 and a tie rod 3. The front end of the tie rod 3 is provided with an external thread section 301, and a tie rod nut 4 is screwed on the external thread section 301. The piston 2 is sleeved on the tie rod 3 and is located behind the tie rod nut 4. The piston 2 is fixedly connected to the tie rod nut 4. The cylinder body 1 is fixedly installed on the fixed template of the injection molding machine. The cylinder body 1 has an inner cavity 11 for the piston 2 to move forward and backward. The piston 2 includes a plurality of holes 11 arranged coaxially from front to back. The outer diameter of the pushing part 21 is larger than the outer diameter of the guide part 22. The pushing part 21 can be movably arranged in the inner cavity 11 forward and backward. The front end of the pushing part 21 extends forward from the cylinder body 1 and the front end face of the pushing part 21 fits with the rear end face of the pull rod nut 4. The rear of the inner cavity 11 is connected to a guide cavity 12 that penetrates front and back and cooperates with the guide part 22. The guide cavity 12 is coaxial with the pull rod 3, and the guide part 22 can be movably extended into the guide cavity 12 forward and backward.

[0025] In this embodiment, the cylinder body 1 includes a cylinder barrel 101, the front end of which is recessed rearward to form an inner cavity 11. The rear end of the cylinder barrel 101 is provided with a guide cavity 12. A cylinder head 102 is mounted on the front end of the cylinder barrel 101. The cylinder head 102 has a through-hole 13 for extending the front end of the pusher 21. The front end of the pusher 21 can move forward and backward through the extension cavity 13 so that the front end of the pusher 21 is in contact with the rear end of the tie rod nut 4. The cylinder body 1 has a simple structure and low manufacturing cost.

[0026] In this embodiment, the cylinder body 1 has two oil inlets 14. The cylinder head 102 includes a front cover portion 15 and a rear mounting portion 16, arranged sequentially from front to rear. The front cover portion 15 seals the front end of the cylinder barrel 101, while the rear mounting portion 16 extends into and is sealed within the inner cavity 11. A front sealing member is provided between the push portion 21 and the extension cavity 13, and a rear sealing member is provided between the guide portion 22 and the guide cavity 12. This structure ensures stable operation of the cylinder body 1. The front and rear sealing members are typically formed of sealing rings 10, which are simple in structure, easy to install, and low in cost.

[0027] In this embodiment, an annular limiting guide 23 is protruded from the rear outer wall of the push portion 21. This guide 23 cooperates with the inner cavity 11 and is disposed therein for forward and backward movement. A sealing structure is provided between the guide 23 and the inner cavity 11. The guide 23 cooperates with the rear mounting portion 16 to limit the travel of the piston 2. Furthermore, the guide 23 cooperates with the inner cavity 11 to guide the movement of the piston 2, ensuring that the force applied to the pull rod 3 and the piston 2 remain aligned. A sealing ring 10 is typically used as the sealing structure.

[0028] In this specific embodiment, the front end of the push portion 21 is recessed rearwardly and provided with a positioning groove 211. The rear end of the tie rod nut 4 is protruding rearwardly and provided with an annular positioning portion 41 that cooperates with the positioning groove 211. The annular positioning portion 41 is embedded in the positioning groove 211. The cooperation between the positioning groove 211 and the annular positioning portion 41 effectively ensures that the front end of the push portion 21 and the rear end of the tie rod nut 4 can be stably and securely mounted.

[0029] In this embodiment, the annular positioning portion 41 is an annular frustum with an outer diameter gradually decreasing from front to back, which is convenient for installation.

[0030] In this specific embodiment, the pull rod 3 is provided with an anti-rotation mechanism for preventing the pull rod nut 4 from rotating relative to the pull rod 3. The anti-rotation mechanism can effectively prevent the pull rod nut 4 from rotating relative to the pull rod 3 when subjected to force.

[0031] In this embodiment, the anti-rotation mechanism includes a nut end cap 5 fixedly mounted on the front end face of the tie rod 3. The rear end face of the nut end cap 5 is mounted in contact with the front end face of the tie rod 3. The nut end cap 5 is fixedly connected to the tie rod nut 4 via a connecting member 6. The anti-rotation mechanism has a simple structure, low cost, and good anti-rotation effect.

[0032] In this specific embodiment, the front end surface of the tie rod nut 4 is provided with a connecting screw hole 42, and the nut end cap 5 is provided with a connecting hole 52 that is through and matches the connecting screw hole 42. The connecting member 6 is a connecting screw or connecting bolt that matches the connecting screw hole 42. The connecting screw or connecting bolt passes through the connecting hole 52 and is screwed into the connecting screw hole 42 at the corresponding position to achieve the fixed installation between the nut end cap 5 and the tie rod nut 4. The structure is simple, the cost is low, and the installation and disassembly are convenient.

[0033] In this embodiment, the rear end surface of the pull rod nut 4 and the front end surface of the push portion 21 are flat end surfaces, ensuring that the two are stably fitted and that the force transmitted from the piston 2 to the pull rod 3 is in the same direction.

[0034] In this specific embodiment, the tie rod nut 4 and the piston 2 are fixedly connected by a bolt or screw 7. A fixed mounting hole 71 is provided on the tie rod nut 4 and passes through the front and back. A fixed screw hole 72 that cooperates with the bolt or screw 7 is provided at a position corresponding to the fixed mounting hole 71 on the piston 2. The fixed connection between the tie rod nut 4 and the piston 2 is achieved by passing the bolt or screw 7 through the fixed mounting hole 71 and screwing it into the fixed screw hole 72 at the corresponding position.

Claims

1. An anti-fracture structure for a tie rod of an injection molding machine, comprising a cylinder, a piston and a tie rod, characterized in that The front end of the pull rod is provided with an external threaded section, and a pull rod nut is threadedly installed on the external threaded section. The piston is sleeved on the pull rod and is located behind the pull rod nut. The piston is fixedly connected to the pull rod nut. The cylinder body is fixedly installed on the fixed template of the injection molding machine. The cylinder body has an inner cavity for the piston to move back and forth. The piston includes a pushing part and a guide part which are coaxially arranged in sequence from front to back. The outer diameter of the pushing part is larger than the outer diameter of the guide part. The pushing part can be movably arranged in the inner cavity front and back. The front end of the pushing part extends forward from the cylinder body and the front end face of the pushing part fits with the rear end face of the pull rod nut. The rear of the inner cavity is connected to a guide cavity which is through and matched with the guide part. The guide cavity is coaxial with the pull rod, and the guide part can be movably extended into the guide cavity set in the guide cavity front and back. The cylinder body includes a cylinder barrel, the front end of which is recessed rearward to form the inner cavity, the rear end of which is provided with the guide cavity, the front end of which is mounted with a cylinder cover, the cylinder cover having an extension cavity extending front to back for the front end of the pusher to extend, the front end of the pusher being able to movably pass through the extension cavity so that the front end of the pusher is in contact with the rear end of the tie rod nut; The cylinder body is provided with two oil inlets, and the cylinder head includes a front cover portion and a rear mounting portion arranged in sequence from front to rear, the front cover portion being provided to cover the front end surface of the cylinder barrel, the rear mounting portion being inserted into and installed in the inner cavity and being sealed therewith, a front sealing member being provided between the pushing portion and the extending cavity, and a rear sealing member being provided between the guide portion and the guide cavity; An annular limiting guide portion is provided on a protruding portion of the rear outer wall of the pushing portion. The annular limiting guide portion cooperates with the inner cavity and is movably arranged in the inner cavity. A sealing structure is provided between the annular limiting guide portion and the inner cavity. The front end of the pushing portion is recessed rearwardly and provided with a positioning groove, and the rear end of the pull rod nut is protruding rearwardly and provided with an annular positioning portion that matches the positioning groove, and the annular positioning portion is embedded in the positioning groove.

2. The anti-breaking structure of the tie rod of an injection molding machine according to claim 1, characterized in that The annular positioning portion is an annular frustum with an outer diameter gradually decreasing from front to back.

3. The anti-breaking structure of the tie rod of an injection molding machine according to claim 1, characterized in that The pull rod is provided with an anti-rotation mechanism for preventing the pull rod nut from rotating relative to the pull rod.

4. The anti-breaking structure of the tie rod of an injection molding machine according to claim 3, characterized in that The anti-rotation mechanism includes a nut end cover fixedly arranged on the front end face of the pull rod, the rear end face of the nut end cover is fitted with the front end face of the pull rod, and the nut end cover is fixedly connected to the pull rod nut via a connecting member.

5. The anti-breaking structure of the tie rod of an injection molding machine according to claim 4, characterized in that The front end face of the pull rod nut is provided with a connecting screw hole, and the nut end cover is provided with a front-to-back through-connecting hole matching the connecting screw hole. The connecting component is a connecting screw or a connecting bolt matching the connecting screw hole. The connecting screw or the connecting bolt passes through the connecting hole and is screwed into the connecting screw hole at the corresponding position to achieve fixed installation between the nut end cover and the pull rod nut.

6. The anti-breaking structure of the tie rod of an injection molding machine according to claim 1, characterized in that The rear end surface of the pull rod nut and the front end surface of the pushing portion are flat end surfaces.

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