Precise plunger screw head

Abstract

The invention relates to a precise plunger screw head which is fixedly installed at the front end of a screw, the screw is coaxially arranged in a material conveying channel of a material pipe, an injection assembly is arranged at the front end of the material pipe, a plunger sealing part is arranged at the front end of the plunger screw head, and the plunger sealing part is arranged at the front end of the plunger screw head. And a plunger sealing channel matched with the plunger sealing part in a grinding manner is arranged in the injection assembly. The plunger structure is ingeniously integrated into the screw, the integration degree is high, original equipment can be transformed, new equipment does not need to be purchased, and therefore repeated investment is saved, after the precise plunger screw head is adopted, the injection pressure can be increased, the injection weight can be reduced, the phenomena of plastic carbonization and degradation can be reduced, the quality can be improved, and the production cost can be reduced. And the purpose of precise injection molding is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of injection molding, and in particular to a precision plunger screw head. Background Art

[0002] Injection molding is an important part of modern industry. With the continuous improvement of product refinement, the requirements for injection molding precision are also getting higher and higher. In order to achieve precision injection molding, the common practice on the market is to use Sodick's plunger screw, which has a structure like Figure 1 As shown, it mainly includes two parts, one is the screw and the other is the plunger, which are arranged in a V shape. The screw melts the material, pressurizes it and then delivers it to the plunger cavity, and then controls the injection volume by controlling the movement distance of the piston in the plunger. However, the structure volume of the V-shaped plunger screw is large, and the installation space is large. The price of purchasing a new machine is very expensive, and the price of replacing the V-shaped structure injection unit is expensive. Because the raw material is diverted from the upper end to the injection plug tube, the plastic cannot be first in first out, and the plastic at the front end of the injection plug rod stays, resulting in carbonization, black spots and yellowing, and the existing old equipment cannot use the V-shaped structure injection mechanism, and the purchase of a new opportunity will lead to repeated investment.

[0003] Therefore, this field urgently needs a product with higher integration and greater injection pressure. Summary of the invention

[0004] The purpose of the present invention is to provide a precision plunger screw head in order to overcome the defects of the prior art.

[0005] In order to achieve the purpose of the present invention, this application provides the following technical solutions.

[0006] In the first aspect, the present application provides a precision plunger screw head, the precision plunger screw head is fixedly mounted on the front end of the screw, the screw is coaxially arranged in the feeding channel of the material pipe, the front end of the material pipe is provided with an injection assembly, characterized in that the front end of the plunger screw head is provided with a plunger sealing part, and the injection assembly is provided with a plunger sealing channel that is ground with the plunger sealing part. The present application fixes the injection assembly at the front end of the material pipe. As the material enters the injection assembly and gradually fills the injection assembly, the material continues to be fed, and the material will push the screw as a whole to move backward. At this time, the screw is pushed forward by an external force, so that the plunger sealing part enters the plunger channel. Due to the grinding between the plunger channel and the plunger sealing part (that is, the tolerance between the two is very small, when the two slide relative to each other, the material cannot leak out from the gap between the two), at this time, the injection assembly and the plunger screw head form a cavity and a piston structure, and the injection amount of the material can be controlled by controlling the forward distance of the plunger screw head to achieve the purpose of precision injection. Moreover, the present application does not need to provide an additional plunger structure as in the prior art, and the overall volume is roughly the same as that of the existing common screw.

[0007] In one embodiment of the first aspect, a weight-reducing portion is coaxially provided on the top of the plunger sealing portion, the weight-reducing portion is cylindrical, and the outer diameter of the weight-reducing portion is smaller than the outer diameter of the plunger sealing portion. As is well known, in the field of injection molding screws, the cross-sectional area of ​​the screw is inversely proportional to the injection pressure, and the cross-sectional area of ​​the screw is proportional to the injection weight. In the present application, there are two purposes for setting the weight-reducing portion. The first is to reduce the weight of the injection molding to achieve the purpose of lightweight, reduce the residence time of the material in the material pipe, and reduce the occurrence of carbonization. The purpose of setting the plunger sealing portion is first to fine sealant, and the second is to increase the injection pressure.

[0008] In one implementation of the first aspect, a ratio of an outer diameter of the lightening portion to an outer diameter of the plunger sealing portion is 0.1 to 0.9:1.

[0009] In one embodiment of the first aspect, the ratio of the outer diameter of the plunger seal to the outer diameter of the screw is 0.1 to 0.9: 1. The diameter of the plunger seal is preferably from 1D to 100D, and more preferably, the diameter of the plunger seal is 1D to 22D. Of course, it is necessary to ensure that the diameter of the plunger seal is smaller than the diameter of the screw, so as to achieve the function of reducing weight and increasing pressure.

[0010] In one embodiment of the first aspect, a guide portion, a sealing portion and a guide groove portion are sequentially provided between the connecting thread of the plunger screw head and the plunger sealing portion, a meson is fixed on the outside of the guide portion, a check ring is sleeved on the outside of the sealing portion, and the outer diameter of the check ring is ground with the inner diameter of the material pipe feeding channel. The meson, the check ring and the guide groove portion are common structures of existing screws. This is a form of plunger screw head used in this application, which adopts the formation of the meson and the check ring. The check ring and the meson can form a sealing surface when they abut, forming a sealing structure.

[0011] In an implementation of the first aspect, the check ring includes any one of a fork-type check ring and a ring-type check ring, wherein the fork-type check ring is more suitable for scenarios with higher melting speeds.

[0012] In one embodiment of the first aspect, the plunger screw head includes a plunger unit, a conjoined check ring and a marble, the front end of the plunger unit is provided with a plunger sealing portion, the rear end of the plunger unit is provided with a mounting cavity, the front end of the mounting cavity is provided with a plurality of second material transfer channels that are connected inside and outside, and the inner wall of the mounting cavity is provided with an internal thread; the outer wall of the front end of the conjoined check ring is provided with an external thread that matches the internal thread, and is fixedly installed at the rear end of the plunger unit; the axis of the front end of the conjoined check ring is provided with a receiving cavity, the inner wall of the rear end of the receiving cavity is spherical, and the inner wall of the rear end is provided with a first material transfer channel that is connected inside and outside, the inner diameter of the middle part of the receiving cavity is constant, and the opening diameter of the front end of the receiving cavity becomes larger, the marble is placed in the receiving cavity, and the diameter of the marble is the same as the diameter of the inner wall of the rear end of the receiving cavity; the rear end of the conjoined check ring is provided with a connecting screw thread, and is fixed to the front end axis of the screw through the connecting screw thread. This is the second form of the plunger screw head of the present application, which uses the forward and backward movement of the marble to achieve the switching between sealing and feeding.

[0013] In one embodiment of the first aspect, the injection assembly includes a plunger cylinder and a nozzle, a plunger sealing channel is provided at the axis of the plunger cylinder, the plunger cylinder is fixedly mounted at the front end of the material tube, and the nozzle is fixedly mounted at the front end of the plunger cylinder.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) The plunger structure is cleverly integrated into the screw, with a high degree of integration, and the volume and weight of the plunger screw are greatly reduced;

[0016] (2) It is suitable for injection molding of different dosages, and by controlling the stroke of the plunger screw head, the extrusion amount of the material is controlled to achieve the purpose of precision injection molding;

[0017] (3) It can increase the injection pressure of the material; at the same time, it can reduce the residence time of the material in the material pipe and reduce the occurrence of carbonization. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a general schematic diagram of a plunger screw of Sodick in the prior art;

[0019] Figure 2 The overall assembly diagram for installing the precision screw head assembly onto the screw;

[0020] Figure 3 It is a structural schematic diagram of the plunger screw head assembly in Example 1;

[0021] Figure 4 It is a partial enlarged schematic diagram of the plunger screw head during the glue injection process;

[0022] Figure 5This is a partial enlarged schematic diagram of the screw head group at the beginning of injection molding;

[0023] Figure 6 It is a partial enlarged schematic diagram of the screw head assembly when the screw continues to push forward;

[0024] Figure 7 This is a partial enlarged schematic diagram of the screw head assembly when the screw restarts to feed glue;

[0025] Figure 8 It is the structural schematic diagram of the plunger cylinder;

[0026] Fig. 9 This is a schematic diagram of the overall structure of the plunger screw head in Example 2;

[0027] Fig.10 for Figure 3 Structural schematic diagram of the middle plunger unit;

[0028] Fig.11 for Figure 3 Structural schematic diagram of the middle joint check ring;

[0029] Fig.12 This is a schematic diagram of the structure of the plunger screw head when it is sealed with glue in Example 2;

[0030] Fig.13 It is a schematic diagram of the structure when the plunger screw head and the plunger cylinder are sealed with glue.

[0031] In the accompanying drawings, 1 is a material pipe, 11 is a feed port, 2 is a screw, 3 is a plunger cylinder, 31 is a connecting channel, 32 is a plunger sealing channel, 33 is an installation channel, 4 is a plunger screw head, 41 is a weight reduction portion, 42 is a plunger sealing portion, 43 is a connecting portion, 431 is a first feed channel, 432 is a mounting cavity, 433 is an internal thread, 44 is a connected check ring, 441 is a second feed channel, 442 is a connecting thread, 443 is a accommodating cavity, 444 is an external thread, 45 is a marble, 46 is a guide groove portion, 47 is a sealing portion, 48 is a guide portion, 49 is a connecting thread, 5 is a nozzle, 6 is a check ring, and 7 is a meson. DETAILED DESCRIPTION

[0032] Unless otherwise defined, the technical or scientific terms used in this specification and claims shall have the ordinary meanings understood by persons having ordinary skills in the technical field to which the present invention belongs. All the values ​​from the lowest value to the highest value listed herein refer to all the values ​​obtained by incrementing one unit between the lowest value and the highest value when the difference between the lowest value and the highest value is more than two units.

[0033] The specific embodiments of the present invention will be described below. It should be noted that in the specific description of these embodiments, for the sake of concise description, it is impossible for this specification to describe all the features of the actual embodiments in detail. Without departing from the spirit and scope of the present invention, those skilled in the art may modify and replace the embodiments of the present invention, and the resulting embodiments are also within the scope of protection of the present invention.

[0034] Example

[0035] The embodiments of the present invention will be described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0036] Example 1

[0037] A precision screw head assembly, after being assembled on an injection molding machine, has a structure as follows Figure 2 The precision screw head assembly includes a plunger screw head 4 and a plunger cylinder 3, wherein the plunger cylinder 3 is fixedly connected to the top of a material pipe 1 of an injection molding machine, a nozzle 5 is fixed to the front end of the plunger cylinder 3, the plunger screw head 4 is fixedly installed on the top of the screw 2, and a feed port 11 is provided on the material pipe 1.

[0038] The structure of the plunger screw head group is as follows Figure 3 As shown, in this embodiment, the so-called plunger screw head assembly refers to the name after the plunger screw head 4 is assembled into a whole with the check ring 6 and the meson 7. Among them, the plunger screw head 4 is an integrated structure, which includes a weight reduction portion 41, a plunger sealing portion 42, a guide groove portion 46, a sealing portion 47, a guide portion 48 and a connecting screw 49 from the head to the back, wherein the connecting screw 49 is fixed at the front end center of the screw 2, and the plunger screw head 4 and the screw 2 are fixed by a thread. The diameter of the plunger sealing portion 42 is smaller than the diameter of the screw 2, which has the effect of reducing weight and increasing pressure. At the same time, the diameter of the weight reduction portion 41 is smaller than the diameter of the plunger sealing portion 42, which further has the effect of reducing weight and increasing pressure. The meson 7 is fixed on the outside of the guide portion 48, and the two are fixed by threaded connection. Four guide grooves are opened on the periphery of the guide groove portion 46 and are glued. The check ring 6 is sleeved on the outside of the sealing part 47, and the axial length of the sealing part 47 is greater than the axial length of the check ring 6, that is, the relative position of the check ring 6 and the plunger screw head 4 is that the front end face of the check ring 6 abuts against the tail end face of the guide groove part 46, and the rear end face of the check ring 6 abuts against the front end face of the meson 7. The check ring can be a ring-type check ring or a fork-type check ring, both of which are existing technologies. The outer diameter of the check ring 6 is ground with the inner wall of the material tube 1, as shown in FIG. Figures 4 to 7 shown.

[0039] The structure of the plunger cylinder 3 is as follows Figure 8 As shown, its structure is similar to the flange in the ordinary screw 2, and it is fixed to the front end of the material tube 1 by several bolts. A through channel is provided at the axis of the plunger cylinder 3, and from the front end to the rear end, there are the installation channel 33, the plunger sealing channel 32 and the connecting channel 31. Among them, the inner diameter of the connecting channel 31 is the same as the inner diameter of the material tube 1, and they are interpenetrating without gaps. The inner diameter of the plunger sealing channel 32 and the outer diameter of the plunger sealing part 42 are precisely ground (that is, the tolerance between the two is less than 0.01mm, but relative sliding can occur between the two). The axial length of the plunger sealing channel 32 is greater than the axial length of the plunger sealing part 42. The inner wall of the installation channel 33 is provided with threads, and the nozzle 5 is fixedly installed in the installation channel 33. When the plunger sealing part 42 begins to be inserted into the plunger sealing channel 32, at this time, the material is cut off by the plunger sealing part 42, which has the effect of sealing. At this time, as long as the forward distance of the plunger sealing part 42 is controlled, the volume of the material ejected from the nozzle 5 can be controlled, which has the effect of precision injection molding.

[0040] The whole working process is as follows:

[0041] During injection, as the screw 2 rotates, the molten material flows forward. At this time, the check ring 6 is located at the front end, that is, the front end of the check ring 6 abuts against the rear end of the guide groove 46, and the plunger sealing portion 42 is not inserted into the plunger sealing channel 32. Figure 4 As shown. The flow path of the material is: the gap between the screw 2 and the inner wall of the material tube 1 → the gap between the meson 7 and the inner wall of the material tube 1 → the gap between the inner wall of the check ring 6 and the outer wall of the sealing part 47 → the guide groove → the channel of the plunger cylinder 3 → the channel of the nozzle 5. Because the mold is in contact with the nozzle 5, the cold glue port in the mold prevents the material from flowing out from the front end of the nozzle 5, and the material will gradually be stored in the channel of the nozzle 5. After the stored material fills the channel of the nozzle 5 and the plunger cylinder 3, when the material continues to be fed, the volume of the material in the metering chamber gradually increases, and a reverse thrust is generated, and the screw and the plunger screw head 4 will gradually move backward.

[0042] When the injection molding starts, the outlet at the front end of the nozzle 5 is opened first, and then the screw 2 is pushed forward by the driving device. At this time, the screw 2, the entire plunger screw head 4 and the meson 7 will move forward. Since the check ring 6 is only sleeved on the outside of the sealing portion 47, that is, it is not fixed, the check ring 6 will not move forward at this time until the front end of the meson 7 on the plunger screw head 4 abuts against the rear end of the check ring 6. Figure 5 As shown. In this way, the check ring 6 and the meson 7 cut off the flow channel of the molten material, that is, the new material cannot flow forward, and the material originally stored in the nozzle 5 and the plunger cylinder 3 cannot flow backward, which plays a sealing effect.

[0043] The driving device drives the screw to continue to move forward. At this time, the screw 2, the plunger screw head 4, the check ring 6, and the meson 7 will move forward together until the plunger sealing portion 42 enters the plunger sealing channel 32. Figure 6 As shown. Since the tolerance between the plunger seal 42 and the plunger seal channel 32 is very small, a structure similar to a syringe and a piston is formed. When the screw 2 continues to move forward, the plunger seal 42 can push the material forward, thereby ejecting the material from the nozzle. Since the diameter of the plunger seal channel 32 is fixed, the injection volume of the material can be accurately controlled by controlling the forward length of the plunger seal 42 (i.e., the stroke of the screw).

[0044] When the injection molding is completed, the melt driving device starts to rotate, and the material is pushed from the discharge port to the metering chamber by the thrust generated by the screw edge angle. When the material is pushed to the tail end of the check ring 6, the material pushes the check ring 6 to move forward until the front end of the check ring 6 abuts against the tail end of the guide groove 46. In this way, the flow channel of the molten material is reopened. Figure 7 As the volume of the material in the metering chamber does not increase and the material cannot flow out from the front hole of the nozzle 5, the material will generate a reverse thrust to push the plunger screw assembly to continue to move backward until the plunger sealing portion 42 is completely pulled out of the plunger sealing channel 32, and then it returns to the state as shown in FIG. Figure 4 In the state shown, the next injection molding can be continued.

[0045] Example 2

[0046] The material pipe, screw, plunger cylinder and nozzle similar to those in Example 1 are used, except that a different form of plunger screw head is used, as described below.

[0047] In this embodiment, the structure of the plunger screw head 4 is as follows: Figures 9 to 13As shown, it mainly includes two detachable parts. The front part is a plunger unit, which includes a weight reduction part 41, a plunger sealing part 42 and a connecting part 43 in sequence. The three are an integrated structure. A mounting cavity 432 is provided at the axis of the tail end of the connecting part 43. The inner wall of the rear end of the mounting cavity 432 is provided with an internal thread 433. The front end of the mounting cavity 432 is provided with a first material transfer channel 431 that penetrates inside and outside. The rear part of the plunger screw head 4 is a conjoined check ring 44. A receiving cavity 443 is provided at the axis of the front end of the conjoined check ring 44. The inner wall of the tail end of the receiving cavity 443 is spherical, and the inner wall of the tail end is provided with a second material transfer channel 441 that penetrates inside and outside. The opening diameter of the front end of the receiving cavity 443 becomes larger. An external thread 444 is provided at the outer wall of the front end of the conjoined check ring 44. The external thread 444 is meshed with the internal thread 433 at the axis of the connecting part 43, so that the plunger screw head 4 is fixed front and back as a whole. The outer diameter of the joint of the check ring 44 and the connecting part 43 is ground to the inner diameter of the material tube 1. A connecting thread 442 is provided on the outer wall of the tail end of the check ring 44, and the entire plunger screw head 4 is fixed to the front end of the screw 2 through the connecting thread 442. A marble 45 is provided in the accommodating chamber 443, and the diameter of the marble 45 is the same as the diameter of the inner wall of the tail end of the accommodating chamber 443. The marble 45 can roll back and forth in the accommodating chamber 443, and when the marble 45 abuts against the side wall of the tail end of the accommodating chamber 443, the marble 45 can block the entire second material transfer channel 441, playing the role of sealing; when the marble 45 is separated from the tail end of the accommodating chamber 443, the material can pass through the second material transfer channel 441, the accommodating chamber 443, the installation cavity 432, the first material transfer channel 431 in sequence, and finally reach the plunger cylinder 3.

[0048] The specific process is as follows:

[0049] When feeding the glue, the material enters the material pipe 1 from the feed port 11. Under the conveyance of the screw 2, the material melts and becomes a colloid. It moves forward from the rear end of the material pipe 1. When it reaches the integral check ring 44 of the plunger screw head 4, since the integral check ring 44 and the inner wall of the material pipe 1 are in a grinding state, the material can only enter from the second feed channel 441, and then pass through the accommodating cavity 443, the installation cavity 432, the first feed channel 431, and the plunger cylinder 3 in turn, and finally reach the nozzle 5. The nozzle 5 is controlled not to discharge the material, and the material is gradually stored in the channel of the nozzle 5. After the stored material fills the channels of the nozzle 5 and the plunger cylinder 3, when feeding continues, the screw 2 and the plunger screw head 4 will gradually move backwards.

[0050] When starting injection molding, first open the outlet at the front end of the nozzle 5, then push the screw 2 forward, and the entire plunger screw head 4 will move forward together. Due to the existence of inertia, the forward speed of the accommodating chamber 443 must be greater than the marble 45, so the marble 45 will gradually retreat relative to the accommodating chamber 443 until it abuts against the inner wall of the rear end of the accommodating chamber 443. In this way, the marble 45 will completely block all the second material transfer channels 441, forming a sealed state, such as Fig.12 As shown, new material cannot flow forward, and the material originally stored in the nozzle 5 and the plunger cylinder 3 cannot flow backward.

[0051] Continue to push the screw 2 forward until the plunger sealing portion 42 begins to enter the plunger sealing channel 32. Fig.13 As shown. Since the tolerance between the plunger seal 42 and the plunger seal channel 32 is very small, a structure similar to a syringe and a piston is formed. When the screw 2 continues to move forward, the plunger seal 42 can push the material forward, thereby ejecting the material from the nozzle. Since the diameter of the plunger seal channel 32 is fixed, the injection volume of the material can be accurately controlled by controlling the forward length of the plunger seal 42 (i.e., the stroke of the screw 2).

[0052] When the injection molding is completed, the control screw 2 moves backward as a whole, the marble 45 first disengages from the tail end of the accommodating chamber 443, the second material transfer channel 441 is reopened, and new material can be injected forward; then the plunger sealing part 42 also disengages from the plunger sealing channel 32, and the material can enter the plunger cylinder 3 and the nozzle 5.

[0053] The above description of the embodiments is to facilitate those of ordinary skill in the art to understand and apply the present application. It is obvious that those familiar with the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without having to pay creative labor. Therefore, the present application is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the contents disclosed in the present application without departing from the scope and spirit of the present application are within the scope of the present application.

Claims

1. A precision plunger screw head, wherein the precision plunger screw head is fixedly mounted at the front end of the screw, the screw is coaxially arranged in the feeding channel of the material pipe, and the front end of the material pipe is provided with an injection assembly, characterized in that: A plunger sealing portion is provided at the front end of the plunger screw head, and a plunger sealing channel which is ground with the plunger sealing portion is provided in the injection assembly.

2. The precision plunger screw head according to claim 1, characterized in that: A weight-reducing portion is coaxially arranged on the top of the plunger sealing portion. The weight-reducing portion is cylindrical, and the outer diameter of the weight-reducing portion is smaller than the outer diameter of the plunger sealing portion.

3. The precision plunger screw head according to claim 2, characterized in that: The ratio of the outer diameter of the weight-reducing portion to the outer diameter of the plunger sealing portion is 0.1 to 0.9:

1.

4. The precision plunger screw head according to claim 1, characterized in that: The ratio of the outer diameter of the plunger sealing portion to the outer diameter of the screw is 0.1 to 0.9:

1.

5. The precision plunger screw head according to claim 1, characterized in that: A guide portion, a sealing portion and a guide groove portion are sequentially arranged between the connecting thread of the plunger screw head and the plunger sealing portion, a pion is fixed on the outer side of the guide portion, a check ring is sleeved on the outer side of the sealing portion, and the outer diameter of the check ring is ground to the inner diameter of the material pipe feeding channel.

6. The precision plunger screw head according to claim 5, characterized in that: The check ring includes any one of a fork-type check ring and a ring-type check ring.

7. The precision plunger screw head according to claim 1, characterized in that: The plunger screw head includes a plunger unit, a connected check ring and a marble. The front end of the plunger unit is provided with a plunger sealing portion, and the rear end of the plunger unit is provided with an installation cavity. The front end of the installation cavity is provided with a plurality of second material transfer channels that pass through inside and outside, and the inner wall of the installation cavity is provided with an internal thread; the outer wall of the front end of the connected check ring is provided with an external thread matching the internal thread, and is fixedly installed on the rear end of the plunger unit; an accommodating cavity is provided at the axis center of the front end of the connected check ring, the inner wall of the rear end of the accommodating cavity is spherical, and the inner wall of the rear end is provided with a first material transfer channel that passes through inside and outside, the inner diameter of the middle part of the accommodating cavity is constant, and the diameter of the opening of the front end of the accommodating cavity becomes larger, the marble is placed in the accommodating cavity, and the diameter of the marble is the same as the diameter of the inner wall of the rear end of the accommodating cavity; the rear end of the connected check ring is provided with a connecting screw thread, and is fixed to the front end axis center of the screw through the connecting screw thread.

8. The precision plunger screw head according to claim 1, characterized in that: The injection assembly comprises a plunger cylinder and a nozzle. A plunger sealing channel is provided at the axis of the plunger cylinder. The plunger cylinder is fixedly mounted at the front end of the material tube, and the nozzle is fixedly mounted at the front end of the plunger cylinder.

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