A self-locking plunger injection structure

Abstract

The application discloses a self-locking plunger injection structure, which comprises an injection mechanism arranged on a machine table, wherein the injection mechanism comprises a plunger storage part used for storing glue for waiting for injection, a plunger injection oil cylinder part used for pushing the plunger in the plunger storage part to inject the glue into a mold, and a self-locking hinge shaft mechanism used for connecting the plunger storage part and the plunger injection oil cylinder part. The self-locking hinge shaft mechanism absorbs the backward movement of the plunger during feeding and locks the plunger during injection. The self-locking hinge shaft mechanism can set an upper limit for the reaction force through a mechanical mechanism during feeding, and can self-lock the injection mechanism 1 during injection, so that the reaction force does not interfere with the oil cylinder pushing, thereby keeping stable injection pressure and improving product quality.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of injection molding machine manufacturing, and in particular to a self-locking plunger injection structure. BACKGROUND

[0002] The plunger injection molding machine is a common injection molding equipment, which is used for completing the molding process of plastic products by means of the following steps: the molten plastic is pressed into an injection cylinder by a plunger pump, and then is injected into a mold through a nozzle.

[0003] The plunger injection molding machine mainly comprises a plunger pump, an injection cylinder, a mold, a heater, a control system and the like. The plunger pump is a core component of the injection molding machine, which sends the glue, i.e. the molten plastic, into the injection cylinder through the up-down movement of the plunger, and injects the glue into the mold under a certain pressure. The injection cylinder is a container for storing and heating the plastic, which is usually controlled by a heater and a temperature controller to ensure the melting temperature and stability of the plastic. When the glue is sent to the injection cylinder, the reaction force generated by the glue will push the plunger in the injection cylinder backward while the glue is filling the injection cylinder, and the reaction force is proportional to the feeding pressure, which will cause the preset position of the plunger to change and the injection pressure to decrease, thereby interfering with the injection action and affecting the injection molding quality. At present, the only way to solve this problem is to fix the plunger, but this way will affect the adjustment and control of the injection pressure, and is not an ideal solution.

[0004] For example, the Chinese patent with the application number CN202210765582.7 discloses a locking nozzle for an injection molding machine and a molding method. The locking nozzle comprises a nozzle transition body, a nozzle head, a nozzle valve core, a nozzle barrel, a limit switch and a nozzle oil cylinder. The nozzle transition body is located in front of the injection cylinder of the injection molding machine and is fixedly connected with the nozzle head through the nozzle barrel. The nozzle valve core is fixedly connected with the piston rod of the nozzle oil cylinder, and is sleeved on the nozzle transition body and finally on the nozzle head. The starting position, the midpoint of the stroke and the terminal position of the piston rod on the nozzle oil cylinder are respectively provided with three limit switches that can sense the corresponding positions. The working condition of the nozzle is transmitted to the controller in a digital input mode.

[0005] The above-mentioned scheme can effectively open and close the nozzle head, adapt to large equivalent injection conditions, ensure that enough back pressure can be generated in the nozzle when it is closed, and ensure the molding pressure. However, the reaction force generated when the glue is injected into the injection cylinder cannot be avoided by only controlling the opening and closing of the nozzle, and this problem has not been properly solved. The only way to resist or control the reaction force is to pressurize again, which is actually not ideal. SUMMARY

[0006] The prior art injection molding machine in the background art has the problem that the reaction force generated by the material is proportional to the injection pressure during the injection molding process, so an additional structure is needed to maintain the injection pressure, resulting in a complex device structure and difficulty in improving the injection pressure.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] A self-locking plunger injection structure, comprising an injection mechanism arranged on a machine table, the injection mechanism comprising:

[0009] A plunger storage part for storing material for injection;

[0010] A plunger injection cylinder part for pushing the plunger in the plunger storage part to inject the material into the mold;

[0011] A self-locking hinge shaft mechanism for connecting the plunger storage part and the plunger injection cylinder part;

[0012] The self-locking hinge shaft mechanism absorbs the backward movement of the plunger during feeding and locks the plunger during injection. The plunger injection cylinder part pushes the plunger arranged in the plunger storage part to inject the stored molten material into the mold. When the plunger enters the storage cavity from the feeding port of the plunger storage part, the feeding pressure will be converted into a reaction force on the plunger. This reaction force will cause the oil pressure of the plunger injection cylinder part to be unstable or lost after acting on the plunger injection cylinder part. The size of this reaction force will change according to the feeding pressure, so it is difficult to adjust the holding pressure of the plunger injection cylinder part according to the size of the reaction force before injection molding, which may affect product quality due to unstable oil pressure. The self-locking hinge shaft mechanism can set an upper limit for the reaction force through a mechanical mechanism during feeding, and self-lock the injection mechanism during injection, avoiding the interference of the reaction force on the oil cylinder advancement, so as to obtain stable injection pressure and improve product quality.

[0013] Further, the plunger storage part and the plunger injection cylinder part are connected by a support rod group, the plunger storage part includes a base plate slidably connected to the machine table, and the support rod group penetrates the base plate; the plunger tail part is arranged on the base plate and is inserted into the plunger storage part, and the two ends of the self-locking hinge shaft mechanism are respectively hinged to the base plate and the plunger injection cylinder part. The plunger storage part is arranged by the base plate, which ensures that the plunger can run smoothly in the injection cylinder combined with the mold, and the support rod group ensures that the self-locking hinge shaft mechanism runs smoothly between the plunger storage part and the plunger injection cylinder part, thereby realizing the cooperative work of the self-locking hinge shaft mechanism and the plunger. When feeding, the plunger moves backward, and the self-locking hinge shaft mechanism absorbs the backward movement of the plunger without changing the distance between the plunger storage part and the plunger injection cylinder part. When the feeding is completed, the hinge shaft mechanism deforms to a self-locking state under the action of the feeding reaction force; then, when the plunger injection cylinder part starts to push the plunger for injection, the plunger is kept stable feeding by the dead point formed by the plunger injection cylinder part.

[0014] As a preferred, the self-locking hinge shaft mechanism includes a hinge transition piece, the hinge transition piece includes a side plate slidably connected to the support rod group, and the side plate is provided with a transition joint; the telescopic rod arranged on the plunger injection cylinder part is connected to the transition joint; the front side and the rear side of the transition joint are respectively hinged to a front arm and a rear arm, the front arm is hinged to the base plate, and the rear arm is hinged to the plunger injection cylinder. The hinge transition piece includes a transition joint that can slide on the support rod group through the side plate, the transition joint transitions the front arm and the rear arm, and cooperates with them to move forward and backward, which can not only absorb the displacement of the plunger backward movement by deformation, but also can limit and lock the plunger by using the absorbed form to keep the pressure stable during the plunger feeding, and the transition joint structure is simple, only assembled between the plunger storage part and the plunger injection cylinder part, without occupying extra space, and the actual use effect is ideal.

[0015] As a preferred, the transition joint includes at least two groups of center twist points, the center twist points are hinged to adjust arms, one end of the adjust arms away from the center twist points is provided with a link twist point, and the front arm and the rear arm are hinged through the link twist point. The transition joint controls the position of the link twist point through the adjust arm, thereby controlling the posture of the front arm and the rear arm, and at least two groups of center twist points are arranged on the transition joint. When the transition joint moves, the adjust arms arranged on the center twist points of each group move synchronously, thereby realizing the movement and deformation of the self-locking hinge shaft mechanism with the entire transition joint.

[0016] As a preferred, each group of center twist points on the transition joint is arranged in a central symmetry. Each group of center twist points represents a group of multi-link self-locking mechanisms, and the pressure is uniformly dispersed through the plurality of groups of multi-link self-locking mechanisms arranged in a central symmetry, which can ensure that the entire self-locking hinge shaft mechanism has sufficient structural strength to withstand the reaction force of the plunger and the injection pressure of the plunger injection cylinder part, thereby ensuring that the injection work of the injection mechanism 1 is smoothly completed.

[0017] As preferred, the plunger injection cylinder part comprises a cylinder body and the telescopic rod, when the telescopic rod is extended to the maximum position, the front arm and the rear arm are collinear. The telescopic rod serves as an execution member for outputting the cylinder pressure of the plunger injection cylinder part, when the injection action is performed, with the telescopic rod advancing, the front arm and the rear arm in the self-locking hinge shaft mechanism gradually reach the same straight line with the movement of the adjusting arm, after the front arm and the rear arm are collinear, a dead point is formed, at this time, the axial pressure in the injection mechanism is all applied to the "straight shaft" composed of the front arm, the rear arm and the connecting twist point, and no radial component force is generated, and through the self-locking structure, the high stability of the pressure maintaining process is realized.

[0018] As preferred, the length of the adjusting arm is less than the length of the rear arm. The adjusting arm is shorter than the rear arm, which can ensure that the adjusting arm is folded at the back of the rear arm after the telescopic rod is retracted, and ensure that the entire self-locking hinge shaft mechanism is kept inside the frame composed of the support rod group in the folded state. This state can ensure that the deformation range of the self-locking hinge shaft mechanism is limited during the plunger feeding injection, and the entire deformation process avoids unnecessary actions, thereby ensuring stable deformation and self-locking.

[0019] A bottom plate is arranged between the plunger storage part and the plunger injection cylinder part, and the bottom plate is slidingly arranged on the machine table. The relative position between the plunger storage part and the plunger injection cylinder part is kept unchanged, but the entire injection mechanism 1 can adjust the axial position on the machine table through the bottom plate according to the position of the mold.

[0020] Therefore, the present application has the following beneficial effects:

[0021] 1) The self-locking hinge shaft mechanism can set an upper limit for the reaction force through a mechanical mechanism during feeding, and self-lock the injection mechanism 1 during injection, thereby avoiding the interference of the reaction force with the cylinder advancement, maintaining stable injection pressure, and improving product quality.

[0022] 2) The self-locking hinge shaft mechanism is used for pressure maintaining, so that the injection mechanism can withstand higher injection pressure, thereby improving the applicable pressure range of the injection mechanism 1 and improving the universality of the device.

[0023] 3) The several groups of multi-link self-locking mechanisms arranged in a central symmetric manner can uniformly disperse the pressure, so that the entire self-locking hinge shaft mechanism has sufficient structural strength to withstand the reaction force of the plunger and the injection pressure of the plunger injection cylinder part. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is an installation schematic diagram of the present application.

[0025] Figure 2 It is an axial side view of the present application before self-locking.

[0026] Figure 3Axonometric view of the self-locking mechanism of the present invention.

[0027] Figure 4 for Figure 2 Side sectional view of the present invention before self-locking.

[0028] Figure 5 for Figure 3 Side sectional view of the self-locking mechanism of the present invention.

[0029] Figure Labels

[0030] 1. Injection mechanism; 11. Plunger storage section; 111. Base plate; 12. Plunger; 13. Feed port; 14. Plunger cavity; 2. Plunger injection cylinder section; 21. Telescopic rod; 22. Cylinder body; 23. Rodless cavity; 3. Self-locking hinge mechanism; 31. Side plate; 32. Front arm; 33. Rear arm; 4. Support rod assembly; 5. Transition section; 51. Center pivot point; 52. Adjusting arm; 53. Connecting pivot point; 6. Base plate; 7. Feed hopper; 8. Mold; 9. Machine base; 10. Plunger pump; 11. Heater. Detailed Implementation

[0031] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] like Figure 1 As shown, the injection mechanism 1 is mounted on the machine base 9. The injection mechanism 1 includes: a plunger storage section 11 for storing rubber material for injection; a plunger injection cylinder section 2 for pushing the plunger 12 in the plunger storage section 11 to inject the rubber material into the mold; and a self-locking hinge mechanism 3 for connecting the plunger storage section 11 and the plunger injection cylinder section 2. The self-locking hinge mechanism 3 absorbs the backward movement of the plunger 12 during the feeding process and locks the plunger 12 during the injection process.

[0034] The injection molding machine used in this embodiment is a plunger pre-plasticizing type injection molding machine. The plasticizing and ejection part melts and heats the injection material to a colloidal state and outputs it to the injection part. The injection part keeps heating and controls the material within a preset temperature range to ensure smooth output injection. The plunger injection cylinder part 2 pushes the plunger arranged in the plunger storage part 11 to inject the stored molten glue into the mold. When the plunger enters its plunger cavity 14 from the feed port 13 of the plunger storage part 11, the feed pressure will be converted into a reaction force on the plunger. This reaction force will cause the oil pressure of the plunger injection cylinder part 2 to be unstable or lost. The size of this reaction force will change according to the feed pressure. Therefore, it is difficult to adjust the holding pressure of the plunger injection cylinder part 2 according to the size of the reaction force before injection. The product quality may be affected due to the instability of the oil pressure. The self-locking hinge shaft mechanism 3 can set an upper limit for the reaction force through a mechanical mechanism during feeding, and self-lock the injection mechanism 1 during injection to avoid the reaction force interfering with the cylinder advance, thereby obtaining stable injection pressure and improving product quality.

[0035] As shown in Figure 2 、 3 , the plunger storage part 11 and the plunger injection cylinder part 2 are connected by a support rod group 4. The plunger storage part 11 includes a base plate 111 slidingly connected to the machine table 9, and the support rod group 4 is connected through the base plate 111. The plunger tail is arranged on the base plate 111 and is inserted into the plunger storage part 11. The self-locking hinge shaft mechanism 3 is hingedly connected to the base plate 111 and the plunger injection cylinder part 2 at both ends. The self-locking hinge shaft mechanism 3 includes a hinge transition piece. The hinge transition piece is an I-shaped structure, including a side plate 31 slidingly connected to the support rod group 4, and a transition joint 5 arranged on the side plate 31. The telescopic rod 21 arranged on the plunger injection cylinder part 2 is connected to the transition joint 5. The front side and the rear side of the transition joint 5 are respectively hingedly connected to a front arm 32 and a rear arm 33. The front arm 32 is hingedly connected to the base plate 111, and the rear arm 33 is hingedly connected to the plunger injection cylinder.

[0036] The plunger storage part 11 arranges the plunger through the base plate 111 to ensure that the plunger can run smoothly in the injection cylinder engaged with the mold. The support rod group 4 ensures that the self-locking hinge shaft mechanism 3 runs smoothly between the plunger storage part 11 and the plunger injection cylinder part 2, thereby realizing the cooperative work of the self-locking hinge shaft mechanism 3 and the plunger. When feeding, the plunger moves backward, and the self-locking hinge shaft mechanism 3 absorbs the backward movement of the plunger without changing the distance between the plunger storage part 11 and the plunger injection cylinder part 2. When the feeding is completed, the hinge shaft mechanism deforms to a self-locking state relying on the feeding reaction force. Then, when the plunger injection cylinder part 2 starts to push the plunger for injection, it keeps the plunger stably fed by the plunger injection cylinder part 2 through the formation of a dead point.

[0037] As shown in Figure 4 、 5As shown, the articulated transition piece comprises a transition joint 5 which can slide on the support rod group 4 through the side plate 31, the transition joint 5 connects the front arm 32 and the rear arm 33 and moves cooperatively with them when moving forward and backward, can absorb the displacement amount of the plunger retraction through deformation, and can use the deformed form to lock the plunger, can keep the pressure of the plunger stable when the plunger feeds, and the transition joint 5 is simple in structure and is only assembled between the plunger storage part 11 and the plunger injection cylinder part 2, does not occupy extra space, and has ideal actual use effect.

[0038] The transition joint 5 comprises at least two groups of central hinge points 51, the adjusting arm 52 is hingedly arranged on the central hinge point 51, the adjusting arm 52 is provided with the connecting hinge point 53 at one end away from the central hinge point 51, and the front arm 32 and the rear arm 33 are hingedly connected through the connecting hinge point 53. Each group of central hinge points 51 on the transition joint 5 is centrally symmetrically arranged. The plunger injection cylinder part 2 comprises the cylinder body 22 and the telescopic rod 21, when the telescopic rod 21 is elongated to the maximum position, the front arm 32 and the rear arm 33 are collinear. The length of the adjusting arm 52 is less than the length of the rear arm 33.

[0039] The transition joint 5 controls the position of the connecting hinge point 53 through the adjusting arm 52, thereby controlling the posture of the front arm 32 and the rear arm 33, at least two groups of central hinge points 51 are arranged on the transition joint 5, and the adjusting arm 52 arranged on each group of central hinge points 51 moves synchronously when the transition joint 5 moves, so that the self-locking hinge shaft mechanism 3 moves and deforms with the entire transition joint 5.

[0040] Each group of central hinge points 51 represents a group of multi-link self-locking mechanisms, a plurality of groups of multi-link self-locking mechanisms arranged in central symmetry uniformly disperse pressure, can ensure that the entire self-locking hinge shaft mechanism 3 has sufficient structural strength to withstand the reaction force of the plunger and the injection pressure of the plunger injection cylinder part 2, thereby ensuring that the injection mechanism 1 can smoothly complete the injection molding work. The telescopic rod 21 is an execution member for outputting the cylinder pressure to the plunger injection cylinder part 2, when the injection action is performed, as the telescopic rod 21 advances, the front arm 32 and the rear arm 33 in the self-locking hinge shaft mechanism 3 gradually reach the same straight line with the movement of the adjusting arm 52, after the front arm 32 and the rear arm 33 are collinear, a dead point is formed, at this time, the axial pressure in the injection mechanism acts on the “straight shaft” composed of the front arm 32, the rear arm 33 and the connecting hinge point 53, no longer generates radial component force, and through this self-locking structure, the pressure maintaining process is highly stable. The adjusting arm 52 is shorter than the rear arm 33, can ensure that the adjusting arm 52 is folded at the back of the rear arm 33 after the telescopic rod 21 is retracted, and ensures that the entire self-locking hinge shaft mechanism 3 is kept inside the frame composed of the support rod group 4 in the folded state, this state can ensure that the deformation range of the self-locking hinge shaft mechanism 3 is limited when the plunger feeds and injects, the entire deformation process avoids unnecessary actions, thereby ensuring stable deformation to complete self-locking.

[0041] The plunger storage part 11 and the plunger injection oil cylinder part 2 are connected with the bottom plate 6, which is slidingly arranged on the machine table 9. The plunger storage part 11 and the plunger injection oil cylinder part 2 keep the relative position unchanged, but the entire injection mechanism 1 can adjust the axial position on the machine table 9 through the bottom plate 6 according to the position of the mold. In this embodiment, the bottom of the bottom plate is provided with a clamp, which is clamped and slidingly connected with the machine table.

[0042] In this embodiment,

[0043] The injection mechanism 1 in this embodiment is a core component of the plunger injection molding machine, which mainly consists of a plunger pump 10, an injection structure, a mold 8, a heater 11, a control system, etc. Among them, the plunger pump is the core component of the injection molding machine, which sends the molten plastic into the injection cylinder through the up and down movement of the plunger, and injects it into the mold under a certain pressure. The injection cylinder is a container for storing and heating plastic, which is usually controlled by a heater and a temperature controller to ensure the melting temperature and stability of the plastic. The injection mechanism 1 in this application corresponds to the injection cylinder, and by adding a self-locking hinge shaft mechanism 3 inside the injection mechanism 1, the internal pressure of the injection mechanism 1 can be controlled: in actual production, the raw materials enter the plasticizing and ejecting component through the feeding hopper 7, are transported by the rotating plasticizing component, and after passing through the heating component, the uniform rubber is sent to the plunger cavity 14 of the injection mechanism 1. While filling the plunger cavity 14, the counterforce generated by the rubber moves the plunger to the set position, at which time the self-locking hinge shaft component is in the open state, and the hinge transition piece is folded and deformed under the counterforce until the required amount of rubber for injection is reached. At this time, the molten glue device stops the molten glue action, and the self-locking hinge shaft component is folded; then the injection action starts, the rodless cavity 23 of the plunger injection oil cylinder part 2 is filled with oil to drive the telescopic rod 21 to feed the plunger, and at the same time drive the hinge shaft mechanism to axially displace and expand, so as to quickly inject the rubber in the plunger cavity 14 into the mold. At this time, the self-locking hinge shaft mechanism 3 is in the straight self-locking state, and the holding pressure from the plunger injection oil cylinder part 2 is self-locked by the "dead point" formed by the self-locking hinge shaft mechanism 3. At this time, the rubber in the mold has not been completely filled, and is filled by the plasticizing and ejecting component under high pressure, and after the holding action, the rubber cools down and the product is taken out from the mold. The self-locking hinge shaft mechanism 3 ensures that the holding pressure remains unchanged by controlling the position of the plunger. After the injection molding work is completed, the position of the telescopic rod 21 of the plunger injection oil cylinder part 2 is adjusted, and the "dead point" state is broken by adjusting the arm 52 to fold back, so that the self-locking hinge shaft mechanism 3 restores to the open state, and the connecting point moves down to realize the inward folding of the front arm and the rear arm, waiting for the next self-locking scene.

[0044] This machine is for multi-cavity, large weight PET tube embryo products, mainly packaging tube embryo, according to the characteristics of PET, using plunger pump + plunger injection cylinder part 2 double-stage injection, solve the low pressure fast injection, high pressure holding, the influence of cycle, with side taking mechanical hand for mold cooling, can be small type production of large weight PET products and greatly shorten the molding cycle.

Claims

1. A self-locking plunger injection structure, comprising an injection mechanism arranged on a machine table, characterized in that, The injection mechanism comprises: A plunger storage part for storing rubber material to be injected; A plunger injection cylinder part for pushing the plunger in the plunger storage part to inject rubber material into a mold; A self-locking hinge shaft mechanism for connecting the plunger storage part and the plunger injection cylinder part; The self-locking hinge shaft mechanism absorbs the backward movement of the plunger during feeding and locks the plunger during injection. The self-locking hinge shaft mechanism comprises a hinge transition piece that is slidingly connected to a support rod group. The hinge transition piece comprises a side plate that is slidingly connected to the support rod group, and a transition joint is arranged on the side plate; an extension rod arranged on the plunger injection cylinder part is connected to the transition joint; a front arm and a rear arm are respectively hingedly connected to the front side and the rear side of the transition joint; the front arm is hingedly connected to a base plate, and the rear arm is hingedly connected to the plunger injection cylinder part.

2. A self-locking plunger injection structure according to claim 1, wherein A support rod group is arranged between the plunger storage part and the plunger injection cylinder part; the plunger storage part comprises a base plate that is slidingly connected to a machine table, and the support rod group penetrates the base plate; a plunger tail is arranged on the base plate and is inserted into the plunger storage part; the self-locking hinge shaft mechanism is hingedly connected to the base plate and the plunger injection cylinder part at both ends.

3. A self-locking plunger injection structure according to claim 2, wherein The hinge transition piece comprises a transition joint that can slide on the support rod group through the side plate; the transition joint transitionally connects the front arm and the rear arm and cooperatively moves with them when moving forward and backward, thereby absorbing the displacement of the backward movement of the plunger and limiting and locking the plunger in the absorbed state.

4. A self-locking plunger injection structure according to claim 3, wherein The transition joint comprises at least two groups of center twist points, and an adjusting arm is hingedly arranged on each center twist point; an end of the adjusting arm away from the center twist point is provided with a linking twist point; the front arm and the rear arm are hingedly connected through the linking twist point.

5. A self-locking plunger injection structure according to claim 4, wherein The center twist points on the transition joint are centrally symmetrically arranged.

6. A self-locking plunger injection structure according to claim 3, wherein The plunger injection cylinder part comprises a cylinder body and the extension rod; when the extension rod is extended to the maximum position, the front arm and the rear arm are collinear.

7. A self-locking plunger injection structure according to claim 4, wherein The length of the adjusting arm is less than the length of the rear arm.

8. A self-locking plunger injection structure according to any one of claims 1-7, wherein, A bottom plate is arranged between the plunger storage part and the plunger injection cylinder part, and the bottom plate is slidingly arranged on the machine table.

Images