Mouth mold and machine head for double-wall corrugated pipe production

Abstract

The utility model discloses a mouth mold and a machine head for producing a double-wall corrugated pipe, which belong to the technical field of corrugated pipe forming equipment, the mouth mold for producing the double-wall corrugated pipe comprises an inner-layer core mold, an inner-layer mouth mold and an outer-layer mouth mold which are sequentially sleeved from inside to outside, a gap between the inner-layer core mold and the inner-layer mouth mold forms an inner-layer discharging channel, and a gap between the outer-layer mouth mold and the inner-layer core mold forms an outer-layer discharging channel. A gap between the outer-layer opening mold and the inner-layer opening mold forms an outer-layer discharging channel, and the shape of a discharging port of the inner-layer discharging channel and the shape of a discharging port of the outer-layer discharging channel are matched with the shapes of the inner wall and the outer wall of the corrugated pipe respectively; the outlines of the sides, close to the die body, of the inner-layer core die and the inner-layer mouth die are gradually in inclined transition from the peripheral edges to the central axis of the die body and are connected with the die body; and a first tangent plane and a second tangent plane corresponding to the discharge port are respectively arranged at four corners of one side, close to the die body, of the inner-layer core die and the inner-layer mouth die. The forming materials at the four corners of the corrugated pipe are supplemented through the first tangent planes and the second tangent planes, and therefore the problem that the wall thickness of the positions is small is solved.

Description

Technical Field

[0001] This utility model relates to the technical field of corrugated pipe production equipment, specifically to a die and die head for producing double-wall corrugated pipes. Background Technology

[0002] Currently, the pipes used in power cables, communication sheaths, and other fields are generally made of polypropylene and HDPE double-wall corrugated pipes, mostly in a circular shape. These pipes are a new type of structural wall material manufactured using high-strength corrugated design and processing technology. They offer a series of advantages, including novel structure, high pressure resistance, rapid and convenient construction, high temperature resistance, flame retardancy, earthquake resistance, and long service life. However, due to their circular structure, circular double-wall corrugated pipes have relatively weak vertical bearing capacity, resulting in poor compressive strength.

[0003] To improve the compressive strength of double-walled corrugated pipes, a corrugated pipe structure with an approximately square outer wall has emerged on the market. For example, the German patent with publication number DE19817109C2 has an arc-shaped top and bottom on the inner and outer walls, while the sides are straight. Although this structure improves the ring stiffness, the arc-shaped bottom makes it easy for voids to exist under the pipe during construction and burial, which cannot provide effective support. This can lead to the pipe tilting and deformation under pressure during long-term use.

[0004] In view of this, the applicant designed a special double-wall corrugated pipe with an inner wall cross-section that is curved at the top and bottom and straight on both sides, while the outer wall cross-section is straight at the top and bottom and curved on both sides. This effectively solved the problem of the pipe body being prone to tilting and deformation under pressure in the above-mentioned scheme. However, this design scheme of the applicant has brought new technical problems to the production, namely, the wall thickness at the intersection of the curved and straight sides of the inner and outer walls of the corrugated pipe is uneven, which makes the compressive strength unable to meet the standard.

[0005] In the aforementioned German patent with publication number DE19817109C2, a relatively long outer nozzle 100, inner nozzle 200, and conveying or flowing channel 400 for extruding the compound are designed. This allows the molten raw material to gradually adapt to the shape of the outer nozzle 100 and inner nozzle 200 in the long conveying channel, and the material is extruded uniformly at the outlet. The Chinese patent with publication number CN218876220U also uses this relatively long die to accommodate the processing of irregularly shaped corrugated pipes, thereby ensuring uniform wall thickness processing of the corrugated pipes. However, this design results in higher mold costs due to the longer irregularly shaped die. Utility Model Content

[0006] The purpose of this utility model is to provide a die and die head for producing double-wall corrugated pipes, which solves the problem that uneven wall thickness is easy to occur during the processing of irregularly shaped corrugated pipes of a specific shape mentioned in this application, and that the traditional irregularly shaped die has a long overall structure, resulting in high mold cost.

[0007] To achieve the above objectives, this utility model provides a die for producing double-walled corrugated pipes, comprising an inner core die, an inner die, and an outer die arranged sequentially from the inside out. The outer die is connected to the die body. The gap between the inner core die and the inner die forms an inner discharge channel, the discharge port of which has upper and lower arc-shaped edges and straight edges on the left and right sides. The gap between the outer die and the inner die forms an outer discharge channel, the discharge port of which also has upper and lower arc-shaped edges and straight edges on the left and right sides. The contours of the inner core die and the inner die near the die body gradually slope from the periphery towards the central axis of the die body and are connected to the die body. The four corners of the inner core die and the inner die near the die body are respectively provided with a first slit and a second slit corresponding to the discharge port. For irregular double-wall corrugated pipes with an inner wall cross-section that is curved at the top and bottom and straight on both sides, while the outer wall cross-section is straight at the top and bottom and curved on both sides, the wall thickness is often thinner at the intersection of the curved and straight walls at the four corners during the production process. By setting a first tangent and a second tangent on the inner core mold and the inner die, the molten polymer material can be diverted, that is, the molding material at that point can be replenished, thereby achieving a uniform wall thickness for both the inner and outer walls of the corrugated pipe.

[0008] Furthermore, the outlets of the inner and outer discharge channels are uniformly sized, allowing for the extrusion of a corrugated pipe with uniform wall thickness when the outlet pressure is consistent. The mold body is equipped with a first and a second feeding channel, respectively connected to the inner and outer discharge channels, facilitating separate control of the material supply to the inner and outer walls of the corrugated pipe. The vertical cross-sections of both the first and second feeding channels are annular, making them suitable for the production of circular double-walled corrugated pipes.

[0009] Furthermore, both the first and second cut surfaces are elliptical cut surfaces; the extended lines of the major axes of the first and second cut surfaces correspond to the intersections of the arc-shaped and straight edges of the inner and outer discharge channels, respectively, and are used to replenish material at the thinner sections of the wall at the intersections of the arc-shaped and straight edges on the inner and outer walls of the corrugated pipe.

[0010] Furthermore, the minor axis radius and major axis radius of the first cross-section are both smaller than the minor axis radius a and major axis radius b of the second cross-section, wherein a≤1 / 2b, guiding the molten material to flow from the center to the intersection of the arc-shaped edge and the straight edge of the discharge port.

[0011] Furthermore, the value of a is greater than or equal to 5mm, and the larger the specification of the irregular corrugated pipe, the greater the value of a.

[0012] Further, the inner edge of the inner core mold is circular. One side of the long axis of the first section plane is connected to the circular inner edge of the inner core mold, and the circular inner edge of the inner core mold is used to correspond to the first feeding channel of the circular mold body.

[0013] Further, a flow splitting end face is arranged on one side of the inner die head close to the mold body. The inner edge of the flow splitting end face is circular, and its outer edge protrudes from the mold body mounting surface and has the same shape as the outlet of the outer discharge channel. That is, the outer edge of the flow splitting end face protrudes from the bottom surface of the second feeding channel, and further mixing can be carried out before the material is extruded.

[0014] Further, one side of the long axis of the second section plane is connected to the outer edge of the flow splitting end face, and the distance c between the connection point and the center of the second section plane satisfies 1 / 2b ≤ c < b. Since the outer edge of the flow splitting end face protrudes from the bottom surface of the second feeding channel, at this time, more materials tend to flow through the second section plane to the outlet, which is beneficial to the realization of uniform wall thickness. The inner edge of the flow splitting end face is used to connect with the mold body.

[0015] Further, the distance from the first section plane to the outlet of the inner discharge channel and the distance from the second section plane to the outlet of the outer discharge channel are both greater than or equal to 30 mm. At the outlets of the inner discharge channel and the outer discharge channel, an outlet channel with a length of at least 30 mm is formed by using the inner core mold, the inner die head and the outer die head, so as to balance the pressure at the outlet, which is beneficial to the realization of uniform wall thickness of the overall corrugated pipe.

[0016] The present invention also provides a die head for producing a double-wall corrugated pipe, including the above-mentioned die head for producing a double-wall corrugated pipe.

[0017] Obviously, the elements or features described in the above single embodiment can be used alone or in combination in other embodiments.

[0018] By arranging the first section plane and the second section plane corresponding to the intersections of the arc edges and straight edges on the inner and outer walls of the special-shaped corrugated pipe at the four corners of the inner core mold and the inner die head, the present invention can specifically guide the molten polymer material, that is, supplement the formed material at the intersections of the arc edges and straight edges, so as to solve the problem of thinner wall thickness at this place. And the solution to this problem is realized by the mutual cooperation between the inner core mold, the inner die head and the outer die head. The mold body part still uses the circular mold body on the existing circular double-wall corrugated pipe production equipment, and there is no need to replace it with a special-shaped mold body, which can greatly reduce the mold processing cost. Moreover, when needed, the inner core mold, the inner die head and the outer die head can be quickly replaced, and it can be quickly switched to meet the different production requirements of the special-shaped corrugated pipe and the traditional circular corrugated pipe in the background technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The dimensions and scales in the accompanying drawings do not represent the dimensions and scales of the actual product. The drawings are for illustrative purposes only, and some non-essential elements or features have been omitted for clarity.

[0020] Figure 1 This is a cross-sectional schematic diagram of the die and the mold body of this utility model;

[0021] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0022] Figure 3 This is a structural diagram of the inner core mold and the inner orifice mold;

[0023] Figure 4 This is a schematic diagram of the cross-section of an irregular double-walled corrugated pipe.

[0024] Explanation of reference numerals in the attached figures

[0025] 1. Inner core mold; 2. Inner die; 3. Outer die; 4. Mold body; 5. Inner discharge channel; 6. Outer discharge channel; 7. First cut surface; 8. Second cut surface; 9. First feeding channel; 10. Second feeding channel; 11. Diverting end face. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings. The embodiments described herein are merely preferred embodiments of the present invention. Those skilled in the art can conceive of other ways to implement the present invention based on the preferred embodiments, and such other ways also fall within the scope of the present invention.

[0027] Example 1

[0028] Reference Figures 1-4A die for producing double-walled corrugated pipes includes an inner core die 1, an inner die 2, and an outer die 3, which are sequentially arranged from the inside out. The outer die 3 is connected to a die body 4. The gap between the inner core die 1 and the inner die 2 forms an inner discharge channel 5. The discharge port of the inner discharge channel 5 has upper and lower arc-shaped edges, and the left and right sides are straight edges. The gap between the outer die 3 and the inner die 2 forms an outer discharge channel 6. The discharge port of the outer discharge channel 6 also has upper and lower arc-shaped edges, and the left and right sides are straight edges. The corrugated pipe outer wall, which has upper and lower straight edges and left and right arc-shaped edges, is mainly formed by a corrugated pipe outer wall forming device (not shown in the figure) set on the die head. This is prior art and will not be described in detail in this embodiment. This embodiment mainly provides a die that can uniformly extrude the material required for the inner and outer walls of the corrugated pipe. With the above configuration, the inner discharge channel 5 is used for extruding and molding the inner wall of the irregular double-wall corrugated pipe, and the outer discharge channel 6 is used for extruding and molding the outer wall of the irregular double-wall corrugated pipe. The contours of the inner core mold 1 and the inner orifice mold 2 near the mold body 4 gradually transition from the surrounding edges to a circle towards the central axis of the mold body 4, and are connected to the mold body 4. The four corners of the inner core mold 1 and the inner orifice mold 2 near the mold body 4 are respectively provided with a first cutting surface 7 and a second cutting surface 8 corresponding to the discharge port. The first cutting surface 7 and the second cutting surface 8 are used to guide the molten material and improve the uniformity of the wall thickness of the inner and outer walls of the corrugated pipe.

[0029] The mold body 4 is provided with a first feeding channel 9 and a second feeding channel 10 that are respectively connected to the inner layer discharge channel 5 and the outer layer discharge channel 6. In this embodiment, the vertical cross-section of the first feeding channel 9 and the second feeding channel 10 are both circular, so they can be adapted to the production and processing of circular double-wall corrugated pipes.

[0030] In the prior art, in the production equipment for circular double-wall corrugated pipes, the outlet shape formed by the inner core mold, inner die, and outer die is circular, and the vertical cross-section of the first and second feeding channels inside the mold is annular. The structure of the mold body 4 in this embodiment is the same as that in the prior art, except that the inner core mold and inner die in the die are provided with the first tangent 7 and the second tangent 8, and the shape of the outlet matches the inner and outer wall shapes of the irregular double-wall corrugated pipe. Therefore, the die in this application can be directly replaced with the die of the circular double-wall corrugated pipe in the prior art to realize the production of irregular double-wall corrugated pipes without the need to prepare a long irregular mold body, thereby saving mold costs. It can also be adapted to the rapid switching between the production needs of circular double-wall corrugated pipes and irregular double-wall corrugated pipes in actual production, improving the line changeover efficiency.

[0031] The outlets of the inner discharge channel 5 and the outer discharge channel 6 are set at uniform sizes, and are consistent with the inner and outer wall thicknesses of the double-walled corrugated pipe to be processed. This is the basic condition for the uniform wall thickness of the inner and outer walls of the corrugated pipe. Under the condition that the outlet pressure is consistent, the inner and outer walls of the corrugated pipe with uniform wall thickness can be extruded.

[0032] Both the first cut surface 7 and the second cut surface 8 are elliptical cut surfaces. The extended lines of the major axes of the first cut surface 7 and the second cut surface 8 correspond to the intersections of the arc-shaped and straight edges of the discharge ports of the inner discharge channel 5 and the outer discharge channel 6, respectively, and are used to replenish the thinner wall thickness at the intersections of the arc-shaped and straight edges on the inner and outer walls of the corrugated pipe. This setting can better guide the molten material and improve the material replenishment effect. On the other hand, compared with the die without processing the first cut surface 7 and the second cut surface 8, in this embodiment, after processing the first cut surface 7 and the second cut surface 8 on the inner core die 1 and the inner die 2, the cavity volume at the four corners corresponding to the inner discharge channel 5 and the outer discharge channel 6 is also increased, which is equivalent to storing more material. During extrusion molding, the material at the four corners can be replenished, which is more conducive to solving the problem of thin wall thickness at the four corners.

[0033] The minor axis radius and major axis radius of the first cut surface 7 are both smaller than the minor axis radius *a* and major axis radius *b* of the second cut surface 8. Here, *a* ≤ 1 / 2 *b*, and *a* ≥ 5 mm. The larger the specification of the irregular corrugated pipe, the larger the value of *a*. In the production of double-wall corrugated pipes, the outer wall needs to be corrugated using compressed air and a corrugation forming module. This consumes more molten material per unit time than the inner wall, making it more prone to thinning due to material shortage. Therefore, the specification of the first cut surface 7 is smaller than that of the second cut surface 8.

[0034] The inner edge of the inner core mold 1 is circular, and the long axis side of the first cross-section 7 is connected to the circular inner edge of the inner core mold 1. The circular inner edge of the inner core mold 1 is used to correspond to the first feeding channel 9 of the circular mold body 4.

[0035] The inner die 2 is provided with a flow-dividing end face 11 on the side near the die body 4. The inner edge of the flow-dividing end face 11 is circular, and its outer edge protrudes from the die body mounting surface and its shape is the same as the shape of the discharge port of the outer discharge channel 6. That is, the outer edge of the flow-dividing end face 11 protrudes from the bottom surface of the second feeding channel 6, which can help to further mix the material before extrusion.

[0036] One side of the long axis of the second section 8 is connected to the outer edge of the shunt end face 11, and the distance from the connection point to the center of the second section 8 is c, satisfying 1 / 2b ≤ c < b. The value of c is mainly determined by the outer wall thickness of the bellows and the overall specification size of the bellows. The thicker the outer wall thickness or the larger the overall specification of the bellows, the larger the value of c. The setting that one side of the long axis of the second section 8 is connected to the outer edge of the shunt end face 11 is equivalent to setting a notch on the outer edge of the shunt end face for the second section 8. Since the outer edge of the shunt end face 11 protrudes from the bottom surface of the second feeding channel 10, more materials tend to flow through the second section 8 to the discharge port when extruding materials, which is beneficial to supplement the materials at the four corners of the bellows and promote the realization of uniform outer wall thickness. The inner edge of the shunt end face 11 is used to connect with the die body 4.

[0037] The distance from the first section 7 to the discharge port of the inner layer discharge channel 5 and the distance from the second section 8 to the discharge port of the outer layer discharge channel 6 are both greater than or equal to 30 mm. At the discharge ports of the inner layer discharge channel and the outer layer discharge channel, the inner layer core die, the inner layer die head and the outer layer die head are used to enclose a discharge channel with a length of at least 30 mm, which is beneficial to the pressure balance at the discharge port and further beneficial to the realization of uniform wall thickness of the overall bellows.

[0038] This embodiment provides a comparative example and an improved embodiment for comparison. The melt index of the molten material in the comparative example and the embodiment is 1.2 g / 10 min, the heating temperature of the molten material in the die body 4 is 200 °C, the radius of the upper and lower arc edges of the inner wall of the bellows is 147 mm, the left and right straight wall dimensions are 170 mm, the radius of the left and right arc edges of the outer wall is 220 mm, the dimensions of the upper and lower straight edges are 110 mm. After improvement, the short axis radius of the first section 7 is 10 mm, the long axis radius is 15 mm, the short axis radius of the second section 8 is 15 mm, the long axis radius is 20 mm, the distance c from the connection point of the second section 8 and the shunt end face 11 to the center of the second section 8 is 10 mm, the designed wall thickness of the inner wall of the bellows is 2 mm, and the designed wall thickness of the outer wall is 2.5 mm. Three points are selected for detection at the four corners where the straight edges and arc edges of the inner and outer walls of the bellows intersect. The comparison data of the wall thickness before and after improvement are shown in the following table:

[0039]

[0040]

[0041] The present utility model also provides a die head for producing double-wall bellows, including the above-mentioned die head for producing double-wall bellows.

[0042] In the description of this utility model, it should be noted that the terms "front," "rear," "left," "right," "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0044] The scope of protection of this utility model is defined only by the claims. Thanks to the teachings of this utility model, those skilled in the art will readily recognize that alternative structures to the disclosed structure can be used as feasible alternative implementations, and that the disclosed implementations can be combined to produce new implementations, which also fall within the scope of the appended claims.

Claims

1. A die for producing double-walled corrugated pipes, comprising an inner core die, an inner die, and an outer die arranged sequentially from the inside out, wherein the outer die is connected to a die body, characterized in that, The gap between the inner core mold and the inner die forms the inner discharge channel, and the gap between the outer die and the inner die forms the outer discharge channel. The discharge ports of both the inner and outer discharge channels have upper and lower arc-shaped sides, and the left and right sides are straight sides. The contours of the inner core mold and the inner die near the mold body gradually slope from the four edges towards the central axis of the mold body and are connected to the mold body. The four corners of the inner core mold and the inner die near the mold body are respectively provided with a first cut surface and a second cut surface corresponding to the discharge port.

2. The die for producing double-walled corrugated pipes according to claim 1, characterized in that, The outlets of the inner and outer discharge channels are uniformly sized; the mold body is provided with a first and a second feeding channel that are respectively connected to the inner and outer discharge channels, and the vertical cross-sections of the first and second feeding channels are both annular.

3. The die for producing double-walled corrugated pipes according to claim 2, characterized in that, Both the first and second cut surfaces are elliptical cut surfaces; the extended lines of the major axes of the first and second cut surfaces correspond to the intersections of the arc-shaped and straight edges of the inner and outer discharge channels, respectively.

4. The die for producing double-walled corrugated pipes according to claim 3, characterized in that, The minor axis radius and major axis radius of the first cross-section are both smaller than the minor axis radius a and major axis radius b of the second cross-section, wherein a ≤ 1 / 2b.

5. The die for producing double-walled corrugated pipes according to claim 4, characterized in that, The a ≥ 5 mm.

6. The die for producing double-walled corrugated pipes according to claim 4, characterized in that, The inner edge of the inner core mold is circular, and one side of the long axis of the first cross-section is connected to the circular inner edge of the inner core mold.

7. A die for producing double-walled corrugated pipes according to claim 6, characterized in that, The inner mold has a flow-dividing end face on the side near the mold body. The inner edge of the flow-dividing end face is circular, and the outer edge of the flow-dividing end face protrudes from the mold body mounting surface and has the same shape as the discharge port of the outer discharge channel.

8. A die for producing double-walled corrugated pipes according to claim 7, characterized in that, One side of the major axis of the second sectional surface is connected to the outer edge of the splitter end face, and the distance c between the connection point and the center of the second sectional surface satisfies 1 / 2b ≤ c. <b。 9. A die for producing double-walled corrugated pipes according to claim 7, characterized in that, The distance between the first cut surface and the outlet of the inner layer discharge channel, and the distance between the second cut surface and the outlet of the outer layer discharge channel, are both greater than or equal to 30 mm.

10. A die head for producing double-walled corrugated pipes, characterized in that, The die for producing double-walled corrugated pipes includes any one of claims 1 to 9.

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