Process for producing packaging tubes

Method for producing packaging tube

The invention relates to a method for producing a packaging tube.

A tube body made of single-layer or multi-layer laminated plastic, together with a tube head made of plastic, constitutes a packaging tube. The name of the multi-layer laminated plastic also includes laminated plastic with a metal (aluminum) barrier layer. . The manufacturing of packaging tubes is basically dominated by two technologies. The difference between the two is that for the first item, the prefabricated tube head is connected to the tube body (hereinafter also referred to as "prefabricated tube head technology"); As for the other item, when the tube head is formed, the tube head is connected with the tube body (hereinafter also referred to as "integral molding technology"). The invention belongs to the previous field, that is, to the technical field of prefabricated pipe heads.

In the tube industry, prefabricated tube head technology has been widely promoted. The reason is that, compared with the integral molding technology, higher packaging tube output per unit time (tube body with tube head) can be obtained. In addition, the operation of the machine when assembling the pipe body and the pipe head is simple, and the investment cost of connecting the pipe body and the pipe head is relatively low, and this method can also be extended, that is, after the pipe body and the pipe head are connected, the pipe body is directly installed. Upper closure and so on. The disadvantage of the prefabricated tube head technology is that both the tube body and the tube head require very strict manufacturing tolerances. In addition, it is necessary to precisely adjust the material compatibility between the inner layer material of the tube body and the material of the tube head, and the inner layer is the key part to maintain a good connection between the tube body and the tube head. For example, a polyethylene pipe body, or a pipe body with a polyethylene inner layer, is difficult to connect with a pipe head of the same material on the inner circumference. In order to solve this difficulty, the shoulder of the pipe head is from the pipe body to the nozzle The connection is configured with a barrier layer. This critical material compatibility hinders the full utilization of the technical advantages of the prefabricated tube head. Although the tube body and tube head of different materials can be prefabricated and positioned, they cannot be combined freely in order to meet the requirements of different packaging items.

Starting from the current state of the art, the task of the present invention is to improve the technology of prefabricated tube heads, so as to maintain its advantages and avoid its shortcomings, and propose a new method for producing packaging tubes.

The method of coupling the pipe body and the prefabricated pipe head according to the present invention has the following advantages correspondingly. In the current state of technology, the strict tolerances required for the tube body and the tube head can be significantly relaxed, thus making the manufacturing simpler and faster, that is, the shrinkage deformation during the production of the tube head and the diameter deviation during the production of the tube body are no longer waste products The root cause. The relatively small material portion is squeezed toward the shoulder of the tube, while the circumferential section on the open end of the tube body is embedded in the material portion. The method according to the present invention can be operated with a relatively small extrusion force and a relatively low tool temperature, so that the technical structure of the extrusion tool is greatly simplified compared with the current structure. Relatively low extrusion temperature and simplified extrusion tools, (it is enough to design the extrusion die rod as a ring). It can process the tube heads that are completely customized in batches, and these tube heads have been provided with diaphragms that rotate into a folding closure and close the discharge port. A lining disc for preventing diffusion installed on the side of the shoulder facing the inside of the tube body, etc. This makes it possible to eliminate the known individual processing steps attached to the extrusion process when processing batches of customized tube heads, such as installing closures after extrusion. Therefore, with the help of the method of the present invention, each unit Compared with the current technical method, the output of packaging tubes within a period of time is once again significantly improved. That is to say, the output of packaging tubes can be increased to 200 to 300 packaging tubes per minute without major investment in equipment when implementing this method. However, the existing methods and equipment using prefabricated tube head technology are impossible to achieve. The material compatibility problem that hinders the full utilization of the technical advantages of the prefabricated pipe head is overcome to a large extent by using the method of the present invention. As mentioned earlier, the connection between the shoulder (the part of the tube head) and the tube body is critical, that is, the quality of the connection determines the quality of the packaging tube itself. Because the material suitable for injection molding or extrusion molding of the tube head, that is, the number of plastics, is limited, and the inner layer material of the tube body must be adjusted directly according to this for the purpose of connection, thus restricting the freedom to choose the tube The body is constructed of plastic material. Using the method according to the invention, the part made of plastic-based coupling and packaging material is used for coupling the pipe body and the pipe head, which eliminates the direct compatibility that is known in the state of the art and is necessary there. In this way, for each packaged item, the materials used for the shoulder and the tube body can be individually optimized according to the requirements of the packaged item.

From the following description of the preferred embodiment and the illustrations attached to the embodiment, other advantages, features and details of the present invention can be derived, as shown in the figure: Figure 1: In Figures 1a, 1b, 1c, 1d, 1e, Shows the first method, first put the tube head on the core rod. Then put the part of the connecting material on the pipe head (press down the part).

Figure 2: Figures 2a, 2b, 2c, 2d, 2e show the second method, that is, first put the part of the connecting material on the core rod, and then put the tube head on the core rod with the material part (upward Press material part).

Figure 3: In Figure 3a, a simplified diagram shows a molding space around the core rod near the transition from the core rod circumference to the core rod slope. Figure 3b shows a slope as the outer circumference of the shoulder, which can also be a graded slope.

Fig. 1a schematically shows a circular core rod 10, which is sleeved into a tube body 11 on its axially extending circumferential surface. The upper free end of the core rod 10, that is, its end surface is designed as follows (indicated by the outline), so that the inner surface of the tube head 12 is completely attached to the end surface. The tube head 12 is composed of a disc-shaped shoulder 13, and a hollow cylindrical discharge port 14 protrudes outward from the shoulder 13. Among them, there is a core rod shoulder 15 that is concentric with the core rod 10 and protrudes outwards. The discharge ports 14 are engaged so that the tube head 12 is accurately centered on the free end of the contour of the core rod 10. According to Figure 1a, in the axial direction of the core rod 10, the annular section 16 of the tube body 11 exceeds the transition section 17, or end face, from the inclined surface 18 of the core rod to the outer circumference 19 of the core rod 10. The axial extension length of the annular section 16 depends on At distance A, viewed from the direction of the axis M of the tube head, the free surrounding edge 20 of the ring section 16 should be arranged at this distance A.

According to the present invention, the transition section 17 from the core rod inclined surface 18 to the outer circumference 19 of the core rod 10 is suitable to arrange the graded inclined surface 21 around the core rod 10. It is more reasonable for the graded inclined plane 21 to include two stages 21a and 21b. The first stage 21a starts from the outer circumference of the core rod 10 and transitions to the second stage 21b in the form of an inclined plane in the direction of the axis M. The second stage 21b and the core The rod slope 18 meets. In this case, the diameter of the confluence near the axis M, that is, the size of the circumference of the second stage 21b should be such that the circumference is covered by the outer circumference of the shoulder 13 of the tube head 12, so that the core rod 10 is equipped with a tube When the head 12, the stage 21b and the shoulder 13 together form a notch surface 22 located in the end surface. When viewed in the axial direction, the first stage 21a and the inner circumferential surface of the section 16 of the tube body 11, and the tube head 12 The outer circumference of the shoulder 13 is connected to form an annular space 23 that is open toward the shoulder 13 and extends axially toward the core rod 10. As shown in FIG. 1c, by means of the second stage 21b engaged with the shoulder 13 from below, and the annular space 23 (first stage) connected with the second stage 21b, a molding space F is formed. The material portion 26 made of the connecting material, that is, plastic, which has plasticity by heating, is pressed into the molding space F.

Figures 1b and 1c show the opposite side of an outer circumferential surface (not shown) extending parallel to the axis of the tube head, preferably a circumferential surface designed as a slope (Figure 3b) or a graded slope 25 (Figure 3c). A portion of the coupling material that is placed on the outer surface of the shoulder 13 is indicated by 26. The portion 26 is preferably completely the same ring-shaped, preferably circular, with the lens forming a drop-shaped cross-section, which is suitable for tightly abutting the inner surface of the section 16 covering the annular space 23.

Figures 1d and 1e show a method for joining the pipe body 11 and the pipe head 12. In Fig. 1d, 30 is a ring-shaped female mold. The core rod 10 carries the tube head 12, the tube body 13 and the material part 26 placed on it upwards into the female mold 30, that is, at the beginning of the extrusion process Before; and Figure 1e shows that the extrusion process has ended. The female mold 30 (shown in diagrams only) includes an inner ring 31 that can be pushed in the direction of movement of the core rod 10, preferably pretensioned by a spring, and the inner ring 31 is used as the pressure of the tube head 12 on the core rod. A tight ring, and its outer diameter is used as a molding wall surface of the molding profile of the female mold 30 that can be pushed axially. The molding contour of the female mold 30 is composed of a cylindrical section 32 and a circular arc-shaped contour section 33 in the above case. The section 33 connects the cylindrical section 32 and the outer wall surface of the inner ring 31 together. The inner diameter of the cylindrical section 32 is equivalent to the outer diameter of the core rod 10 plus twice the wall thickness of the selected tube 11. The arc-shaped section 33 is dimensioned in such a way that it forms a transition section with a predetermined size between the tube body 11 and the tube head 12 or between the outer circumference of the shoulder 13 and the tube body 11.

In FIGS. 2a to 2e, the same reference symbols are used to indicate the same parts as in FIGS. 1a to 1e, and at the same time, these parts also perform the same functions. For the method according to FIGS. 2a to 2e, compared with the case according to the method shown in FIGS. 1a to 1e, the fundamental difference is that for the method according to FIGS. 2a to 2e, the material part 26 is first placed in The core rod 10 is placed on the core rod slope 18 on the end surface of the core rod 10, and then the tube head 12 is stacked on the core rod 10, that is, the opposite method is used as shown in FIGS. 1a to 1e. order. The latter is called downward pressure, and the former is called upward pressure (determined according to the extrusion flow direction of part 26 material respectively).

The method according to the invention described in Figures 1a to 1e and 2a to 2e basically comprises six sub-steps. The first sub-step shown in Figures 1a and 2a is to install the tube body 11 on the core rod 10. The installation method is to make the section 16 of the tube body 11 extend beyond the inclined surface 18 of the core rod and the outer circumferential surface 19 of the core rod 10. The formation of the transition section 17. In the second sub-step of the first implementation method shown in Figure 1b, the prefabricated tube head 12 is placed on the core rod 10, through the tube head 12 at the outlet 14 and the core rod shoulder 15, the tube head is It is located concentrically on the core rod 10 and is surrounded by segments 16. When adopting the second implementation method, we first place the material part 26 on the inclined surface 18 of the core rod as a second substep according to Fig. 2b, and surround the inner circumference of the segment 16. That is to say, it is placed on the transition section 17 formed by the inclined surface of the core rod 18 and the outer circumference 19 of the core rod 10. On this basis, according to Figure 2c as the third sub-step, the tube head 12 is stacked concentrically, so , The material part is basically located below the tube head 12. Figure 1c, as the third sub-step of the first implementation method, shows that the connecting material portion 26 has been placed on the side of the shoulder 13 away from the core rod slope 18, that is, on the outside of the shoulder 13, preferably tightly. The inner circumference of the sticker section 16 and extends along the inner circumference. The part 26 can be prefabricated and then embedded, or squeezed into a ring shape and then placed on the shoulder 13 or the inclined surface 18 of the core rod. The core rod 10 loaded in this way enters the fixed, downwardly open annular female mold 30 as shown in the fourth sub-step of Figs. 1d and 2d. In this case, the annular end face of the inner ring 31 and The outer surface of the shoulder 13 of the tube body 12 engages. Figures 1e and 2e show the fifth sub-step, more specifically, the inner surface of the section 16 and the shoulder 12 of the tube body 12 form a closed connection by means of a part 26 made of a plastic connection material. Preferably, under heating and pressurizing, the loaded core rod 10 vertically enters the fixed female mold 30 for extrusion. During the entry process, the inner ring 31 is pushed onto the core rod 10 along the entry direction under the simultaneous compression of the tube head 12, and the material portion 26 is opposite to the direction of movement of the core rod 10 by means of the arc-shaped segment 33 , For example, is squeezed into the annular space 23 and the notch surface 22, and the geometric size of the segment 16 corresponding to the arc shape of the segment 33 is changed in shape, until for example, the free end of the front of the segment 16 and the inclined surface 24 at the shoulder 13 Or the step 25 enters the occluding state. The inclined surface 24 and the graded inclined surface 25 technically have the advantage of enlarging the connection area. Aesthetically, they have the following beneficial effects:

For the second implementation process, the material portion 26 is squeezed upward toward the female mold 30 along the moving direction of the core rod 10. In order to close the shape, in the case of forming a rounded (arc-shaped) transition section between the tube body 11 and the tube head 12, the tube body 11 and the tube head 12 are connected. The connecting material is connected with the material in the annular space 23, and is close to the material inside the section 16, thus strengthening the connection at the inner side of the packaging tube. In addition to strengthening this connection, a very defect-free connection between the tube head 12 and the tube body 11 is also achieved. During the extrusion process, the outer circumference of the inner ring is connected with the pressing function, which also makes the coupling material on the outer surface of the shoulder 13, such as plastic plastic, unable to move or squeeze to flow toward the discharge port 14, so the appearance is A precisely defined flow slit is formed on the shoulder 13. Compared with the current state of the art, the method of directly welding the inner material of the pipe body on the outer circumference of the prefabricated pipe head, or compared to the method of forming the pipe head at the same time when connecting the pipe head and the pipe body In other words, according to the method of the present invention, since the portion 26 is relatively small, the very low heat used for plasticizing and fusing the tube body 11 and the tube head 12 with pressure is sufficient, thus increasing the weld seam and also In other words, even if the cooling time is shortened, a surrounding weld is formed. In principle, according to the present invention, it is possible to use the plastic material part 26 when the female mold 30 is not heated or moderately heated, or in connection with the female mold 30 of the material part 26 heated and plasticized during extrusion, using The material part 26 that is not plastic. The advantage of low heat is that compared with the methods known in the current state of the art, it has a higher processing speed and solves the problem of crystallization of the material part in the female mold before the extrusion process is started and the shoulder plastic is contaminated. In addition, the annular female mold 30 is associated with a relatively small amount of heat used, which allows a fully customized tube head (tube head with a closure diaphragm, rotating or folding closure, etc.) to be connected to the tube body. In this way, the internal annular space of the female mold 30 uses the space for accommodating the various components of the tube head during the extrusion process. After the annular weld formed according to the present invention is cooled, for the sixth sub-step (not shown in the drawing) that is the same for both implementation methods, the core rod 10 is unloaded by removing the tube body 11 and the tube head 12. The mechanical tools of the machine for starting and stopping the method steps outlined above have many forms and will not be introduced here.