Extrusion forming die and method for UPVC elbow

Abstract

The invention provides an extrusion forming die and method for a UPVC elbow. The forming die comprises a die body and at least one forming cavity formed in the die body, and a set of die core assemblies are correspondingly arranged in each forming cavity; each group of mold core assembly comprises a first core mold and a second core mold which are arranged in a sliding manner; each of the first core mold and the second core mold comprises a bending part, a rotating part and a fixing part which are sequentially arranged, a blocking plate for blocking an opening of the forming cavity is arranged on the fixing part, the rotating part is rotationally connected relative to the bending part and the fixing part, and the bending part is connected with the fixing part through a plurality of connecting parts; a penetrating hole allowing the connecting part to penetrate through is formed in the rotating part, a rotating shaft is rotationally arranged in the fixing part, one end of the rotating shaft is fixedly connected with the rotating part, the other end of the rotating shaft is connected with a rotating driving mechanism, the rotating part is arranged in the elbow inner cavity and used for limiting a limiting part of a pipe fitting, and the size and strength of the limiting part can be ensured; therefore, the assembly precision of the elbow is ensured.

Description

Technical Field

[0001] The present invention relates to the field of elbow processing, and more particularly, to an extrusion molding die and method for a UPVC elbow. Background Art

[0002] The current structure of the UPVC elbow is as Figure 1 shown. Generally, as a connecting component of pipe fittings, the elbow is used to connect a horizontal pipe and a vertical pipe. In order to improve the accuracy during connection, a limiting portion for limiting the pipe is usually provided on the inner arm of the elbow. However, the processing technology during the forming process of such elbows is relatively complex, usually including two types. For elbows with a relatively thick wall thickness, the limiting portion can be machined on the inner wall of the elbow after forming. However, for elbows with a relatively thin wall thickness, the mechanical processing method is not applicable. When using injection molding, the core structure is complex, resulting in poor forming accuracy of the limiting portion, and the limiting portion is extremely prone to deformation during core demolding, thereby affecting the assembly accuracy.

[0003] In view of this, those skilled in the art need to improve the current molding die to overcome the above defects. Summary of the Invention

[0004] The main object of the present invention is to provide an extrusion molding die and method for a UPVC elbow, which can ensure the size and strength of the limiting portion, thereby guaranteeing the assembly accuracy of the elbow.

[0005] To achieve the above object, in a first aspect, the present invention provides an extrusion molding die for a UPVC elbow, including a die body and at least one molding cavity opened on the die body, and a set of core components is correspondingly arranged in each molding cavity; Each set of core components includes a first core mold and a second core mold that are slidably arranged, the sliding direction of the first core mold is perpendicular to the sliding direction of the second core mold, and the first core mold and the second core mold are respectively driven to slide by a sliding driving mechanism; Both the first core mold and the second core mold include a bending portion, a rotating portion, and a fixing portion arranged in sequence. A sealing plate for sealing the opening of the molding cavity is arranged on the fixing portion. The rotating portion is rotatably connected to the bending portion and the fixing portion. The bending portion and the fixing portion are connected by a plurality of connecting portions. A through hole for the connecting portion to pass through is opened on the rotating portion. A rotating shaft is rotatably arranged in the fixing portion. One end of the rotating shaft is fixedly connected to the rotating portion, and the other end of the rotating shaft is connected to a rotating driving mechanism. The rotating portion is arranged in the inner cavity of the elbow at the position of the limiting portion for limiting the pipe fitting.

[0006] Preferably, the cross-sections of the bending parts of both the first core mold and the second core mold are circular, and the ends of both have mutually cooperating inclined surfaces.

[0007] Preferably, the first core mold and the second core mold further include an internal cooling assembly.

[0008] Preferably, the internal cooling assembly includes cooling cavities opened on the bending part and the fixing part. The connecting part is a hollow structure, and the connecting part communicates with the cooling cavities of the bending part and the fixing part. An inlet and an outlet that are respectively communicated with the cooling cavity of the fixing part are further provided on the fixing part.

[0009] Preferably, a partition plate that divides the cooling cavity of the fixing part into an inlet cavity and an outlet cavity is fixedly arranged in the cooling cavity of the fixing part. The inlet is communicated with the inlet cavity, and the outlet is communicated with the outlet cavity.

[0010] Preferably, the mold body includes a mold base and a cover plate detachably connected to the mold base, and one side of the forming cavity is opened on the cover plate.

[0011] Preferably, a plurality of cooling channels are opened on the mold base.

[0012] Preferably, the sliding driving mechanism is one of a cylinder and an electric push rod.

[0013] Preferably, the rotational driving mechanism includes a motor and a speed reducer connected to the motor.

[0014] Preferably, using the above-mentioned extrusion molding die for UPVC elbows for processing, includes the following steps: S1. Melting the raw materials through a screw extruder and extruding them into the forming cavity. During the injection process, the rotational driving mechanism drives the rotating part to rotate at a constant speed; S2. After extrusion is completed, a first cooling medium is introduced into the cooling channels on the mold base, and a second cooling medium is introduced into the cooling cavities of the first core mold and the second core mold, and cooling and forming are carried out simultaneously; S3. Starting the rotational driving mechanism to drive the rotating part to rotate, and the rotation speed of the rotating part gradually increases with the cooling time; S4. Starting the sliding driving mechanism to separate the first core mold and the second core mold from the forming cavity, and demolding the product.

[0015] An extrusion molding die and method for a UPVC elbow provided by the present invention, compared with the prior art, have the beneficial effects that by improving the core die structure, it is divided into a bending part, a rotating part, and a fixing part. During the molding process, rotational extrusion is carried out by the rotation of the rotating part, which not only makes the wall thickness uniform and the dimensions accurate, reduces stress deformation, but also reduces the generation of air bubbles and charring phenomena at the limiting part during the molding process, thereby ensuring the product accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention, making other features, objects, and advantages of the present invention more obvious. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a schematic diagram of an elbow; Figure 2 is a schematic diagram of a molding die; Figure 3 is a schematic diagram of a molding cavity; Figure 4 is a schematic diagram of a first core die; Figure 5 is a schematic diagram of a second core die; Figure 6 is a schematic diagram of the cooperation between the first core die and the second core die; Figure 7 is a schematic diagram of a partition board.

[0017] Wherein: 1, die body; 2, cover plate; 3, first core die; 4, second core die; 5, bending part; 6, rotating part; 7, fixing part; 8, connecting part; 9, rotating shaft; 10, plugging plate; 11, partition plate; 12, bushing; 13, liquid inlet; 14, liquid outlet. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] It should be noted that the terms "first", "second", etc. in the specification, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so as to implement the embodiments of the present invention described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0020] In the present invention, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation.

[0021] Moreover, in addition to being used to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0022] In addition, the meaning of the term "plurality" should be two or more.

[0023] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0024] As Figures 2 - 6 shown, an extrusion molding die for a UPVC elbow includes a die body 1 and at least one molding cavity formed in the die body 1, and a set of die core components is correspondingly arranged in each molding cavity; preferably, a plurality of molding cavities are adopted. In this way, when an extruder cooperates with this die, multiple products can be molded simultaneously, and the utilization rate is high.

[0025] Each group of the core mold assemblies includes a first core mold 3 and a second core mold 4 which are slidably arranged, and the sliding direction of the first core mold 3 is perpendicular to the sliding direction of the second core mold 4. The first core mold 3 and the second core mold 4 are driven to slide by a sliding drive mechanism, and the sliding drive mechanism is one of a cylinder and an electric push rod; the sliding drive mechanism drives the first core mold 3 and the second core mold 4 to be demolded simultaneously from both the horizontal direction and the vertical direction, so that after the product is cooled and formed, the simultaneous demolding method is adopted, which can reduce stress deformation and ensure product accuracy. Specifically, for example, by adopting cylinder drive, during operation, the corresponding cylinders first drive the first core mold 3 and the second core mold 4 to be inserted into the molding cavity as a whole, and the gap between the first core mold 3 and the second core mold 4 and the molding cavity is the molding space of the product, and then the material of the extruder is injected into the material from the feeding port of the molding cavity until the entire molding space is filled, thereby completing the feeding process.

[0026] The first core mold 3 and the second core mold 4 each include a bending portion 5, a rotating portion 6 and a fixed portion 7 which are arranged in sequence. The fixed portion 7 is provided with a sealing plate 10 for sealing the opening of the molding cavity. The rotating portion 6 is rotatably connected relative to the bending portion 5 and the fixed portion 7. The bending portion 5 is connected to the fixed portion 7 via a plurality of connecting portions 8. The rotating portion 6 is provided with a through hole for the connecting portion 8 to pass through. A rotating shaft 9 is rotatably arranged in the fixed portion 7. One end of the rotating shaft 9 is fixedly connected to the rotating portion 6, and the other end of the rotating shaft 9 is connected to a rotating drive mechanism. The rotating drive mechanism includes a motor and a reducer connected to the motor. The rotating portion 6 is arranged at a limiting portion in the inner cavity of the elbow for limiting the position of the pipe fitting.

[0027] Because during molding, the structure of this elbow has an additional limiting part compared to conventional elbows, and the difficulty during molding lies in this limiting part. During conventional injection molding, a large number of bubbles are easily gathered in this limiting part and burning occurs. Moreover, during demolding, since the material is not completely cooled and solidified during the demolding period, the limiting part is easily deformed when the core mold is demolded, which in turn affects the accuracy of the entire product and the matching accuracy between the elbow and the pipe fitting, causing leakage after the pipe fitting is connected.

[0028] Due to the setting of the limiting part, the internal structure of the whole elbow is relatively complex. During the molding process, bubbles and charring phenomena often occur at this place. Moreover, the existence of the limiting part makes it extremely easy to cause stress deformation during demolding, which will ultimately affect the molding accuracy of the whole product. By setting the rotating part 6, during the molding process, that is, during the injection of the melt, the rotating part 6 rotates at a low and uniform speed, that is, using the method of rotary extrusion to reduce bubbles and charring phenomena. Moreover, the rotating parts 6 on the first core mold 3 and the second core mold 4 adopt the way of opposite rotation directions, so that the fluids are mutually extruded, thereby making the melt fill the whole molding cavity, making the wall thickness of the elbow part uniform. In the cooling and molding stage, as the cooling progresses, the rotating part 6 rotates in a way that the rotation speed gradually increases, so that during shaping, the limiting part is rotationally extruded to ensure the molding accuracy. Moreover, as the mechanical energy of cooling, during this process, the rotating part 6 and the limiting part are gradually separated. Since the material of the product has a certain viscosity in the molten state, rapid rotation can make the two separate, so that the limiting part will not be affected by stress deformation during demolding, ensuring the accuracy of the product.

[0029] The rotating shafts 9 on both the first core mold 3 and the second core mold 4 are respectively connected to the motor shafts of the corresponding driving motors. The motors are variable-frequency motors, so that the rotation speed of the motor can be adjusted, thereby controlling the rotation speed of the rotating part 6. Specifically, it is set according to the specific process parameters of the product. Taking the cooling time of 1 hour as an example, the rotating part rotates at a low and uniform speed during the material injection stage, and the rotation speed is usually set at 20r / min - 30r / min. For example, during cooling and demolding, the corresponding rotation speed can be set according to the cooling time. It can be selected to increase the rotation speed at a rate of 2r / min until cooling is completed, or the stepwise cooling method can be adopted, such as dividing the overall cooling speed into several stages, and increasing the rotation speed correspondingly in each stage. Thus, during this period, the rotation speed of the rotating part 6 becomes faster and faster as the cooling time progresses. As the cooling progresses, the molten raw material is gradually solidified. Rotation during the early stage of high viscosity can extrude bubbles, while high rotation speed in the later stage makes the rotating part rotating at high speed play the role of polishing the inner wall of the limiting part when contacting the inner wall of the pipe, thereby making this part smoother, without edges, burrs, etc., so that it fits more tightly with the pipe fitting. In addition, due to its continuous rotation, the limiting part and the rotating part 6 are in a separated state during demolding, so that demolding will not affect the limiting part.

[0030] Preferably in this embodiment, the cross-sections of the bending parts 5 of the first core mold 3 and the second core mold 4 are circular, and the ends of the two have mutually cooperating inclined surfaces. The first core mold 3 and the second core mold 4 are mutually cooperated by the inclined surfaces, with a larger contact surface, and the demolding and mold closing are more tightly cooperated.

[0031] In order to be able to cool the product in all directions and make the product cooling more uniform, the first core mold 3 and the second core mold 4 further include an internal cooling component. The mold body 1 includes a mold base and a cover plate 2 detachably connected to the mold base. One side of the molding cavity is opened on the cover plate 2. A number of cooling channels are provided on the mold base. The specific setting of the cooling channels can be to set the channels along the outer contour of the elbow. The cooling medium circulates through the cooling channels and then cools and shapes the outer wall of the elbow. The cooling medium can preferably adopt liquid carbon dioxide. Liquid carbon dioxide is transported to local hot spots of the mold under high pressure and quickly evaporates and absorbs heat to achieve precise cooling. Its cooling rate is 5-8 times faster than water cooling, and it is especially suitable for local temperature reduction of pipes with complex cross-sections.

[0032] Specifically, the internal cooling component includes cooling cavities opened on the bending part 5 and the fixing part 7. The connecting part 8 is a hollow structure. The connecting part 8 communicates with the cooling cavities of the bending part 5 and the fixing part 7. An inlet 13 and an outlet 14 respectively communicating with its cooling cavity are further provided on the fixing part 7. A partition plate 11 that divides its cooling cavity into an inlet cavity and an outlet cavity is fixedly arranged in the cooling cavity of the fixing part 7. The inlet 13 communicates with the inlet cavity, and the outlet 14 communicates with the outlet cavity. The above structure is used to cool and shape the inside of the elbow. The coolant is pumped through the inlet cavity by a pump body, then enters the bending part 5 through the hollow connecting part 8 on one side, and finally returns to the outlet cavity through the hollow connecting part 8 on the other side, and finally returns to the coolant storage tank. A condensing device is arranged in the coolant storage tank to cool the refluxed coolant and recycle it in turn. It should be noted that since the first core mold 3 and the second core mold 4 are driven by a cylinder to slide, the coolant storage tank is connected to the inlet 13 and the outlet 14 through a hose, so that there will be no interference during their movement.

[0033] As Figure 7 shown, it is a schematic diagram of the partition plate 11. One end of it is fixed on the fixing part 7, and the other end has a clearance fit with the rotating part 6. The middle part thereof has a hollow shaft sleeve 12, and a rotating shaft 9 connected to the rotating part 6 is inserted into the shaft sleeve 12.

[0034] It should be noted that the internal cooling component and the cooling channels on the mold base cool the product together, that is, perform internal and external synchronous cooling, which not only improves the cooling efficiency, but also cools more evenly and reduces stress deformation.

[0035] In addition, among the components of the first core mold 3 and the second core mold 4, the bending part 5 and the fixing part 7 are both in a fixed state, while the rotating part 6 rotates at different rotational speeds according to the progress of the process. Also, since the forming material of the elbow is viscous in the molten state, in order to prevent the molten forming material from entering the gap between the rotating part 6, the bending part 5, and the fixing part 7 during injection, a taper angle of 5° - 10° is set on the contact surface between the rotating part 6, the bending part 5, and the fixing part 7. The centrifugal force is used to make the material fly off the gap along the inclined plane, thereby preventing the viscous material after forming from entering the gap and causing interference to the rotating part 6.

[0036] The difference between this mold and the conventional mold lies in that a split core mold is adopted. During demolding, simultaneous demolding on both sides is used to reduce stress deformation. Moreover, a rotating part 6 is provided on the core mold, which can rotate at different rotational speeds according to different forming stages to ensure good dimensional accuracy of the limiting part during melt injection and demolding. In addition, the common cooling molding is carried out by the method of internal and external common cooling, which improves the molding efficiency and the molding effect. Moreover, the core mold with the cooling medium is separated from the elbow during demolding, reducing the viscosity of its material and the demolding difficulty.

[0037] A molding method for UPVC uses the above-mentioned extrusion molding die for UPVC elbows for processing, including the following steps: S1. The raw material is melted by a screw extruder and then extruded into the molding cavity. During the injection process, the rotation drive mechanism drives the rotating part 6 to rotate at a constant speed, and the rotational speed is 30 r / min. S2. After extrusion is completed, the first cooling medium is introduced into the cooling channels on the mold base, and the second cooling medium is introduced into the cooling cavities of the first core mold 3 and the second core mold 4, and cooling molding is carried out simultaneously. Among them, the first cooling medium is water, and the second cooling medium is liquid carbon dioxide. S3. Start the rotation drive mechanism to drive the rotating part 6 to rotate. The rotational speed of the rotating part 6 gradually increases with the cooling time, and the rotational speed is increased at a rate of 2 r / min until cooling is completed. S4. Start the sliding drive mechanism to separate the first core mold 3 and the second core mold 4 from the molding cavity, and demold the product.

[0038] The difference between the above process and the conventional process lies in how to control the rotation of the rotating part 6 during melt injection and cooling molding, and control the rotational speed of the rotating part 6. As a result, the molded product not only has a good wall thickness, but also can reduce the bubbles and burning phenomena at the limiting part, and can ensure the molding accuracy of the limiting part. Therefore, the product does not need to be machined after molding to achieve the accuracy for pipe assembly, and can be perfectly fitted when cooperating with pipe fittings, thus achieving a highly sealed effect.

[0039] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An extrusion molding die for a UPVC elbow, characterized in that It includes a mold body and at least one forming cavity formed on the mold body, and a set of core components are correspondingly arranged in each forming cavity; Each set of the core components includes a first core mold and a second core mold that are slidably arranged. The sliding direction of the first core mold is perpendicular to the sliding direction of the second core mold, and the first core mold and the second core mold are respectively driven to slide by a sliding driving mechanism; Both the first core mold and the second core mold include a bending part, a rotating part and a fixing part arranged in sequence. A sealing plate for sealing the opening of the forming cavity is arranged on the fixing part. The rotating part is rotatably connected to the bending part and the fixing part. The bending part and the fixing part are connected by a plurality of connecting parts. A through hole for the connecting part to pass through is formed on the rotating part. A rotating shaft is rotatably arranged in the fixing part. One end of the rotating shaft is fixedly connected to the rotating part, and the other end of the rotating shaft is connected to a rotating driving mechanism. The rotating part is arranged at the limiting part in the inner cavity of the elbow for limiting the pipe fitting.

2. The extrusion molding die for a UPVC elbow according to claim 1, wherein: The cross-sections of the bending parts of both the first core mold and the second core mold are circular, and the ends of both have mutually cooperating inclined surfaces.

3. The extrusion molding die for a UPVC elbow according to claim 1, characterized in that: Both the first core mold and the second core mold further include an internal cooling component.

4. The extrusion molding die for a UPVC elbow according to claim 3, wherein: The internal cooling component includes cooling cavities formed on the bending part and the fixing part. The connecting part is of a hollow structure, and the connecting part communicates with the cooling cavities of the bending part and the fixing part. An inlet and an outlet respectively communicating with its cooling cavity are further arranged on the fixing part.

5. The extrusion forming die for a UPVC elbow according to claim 4, characterized in that: A partition plate that divides the cooling cavity of the fixing part into an inlet cavity and an outlet cavity is fixedly arranged in the cooling cavity of the fixing part. The inlet is communicated with the inlet cavity, and the outlet is communicated with the outlet cavity.

6. The extrusion molding die for a UPVC elbow according to claim 1, characterized in that: The mold body includes a mold base and a cover plate detachably connected to the mold base. One side opening of the forming cavity is arranged on the cover plate.

7. The extrusion molding die for a UPVC elbow according to claim 6, characterized in that: A plurality of cooling channels are formed on the mold base.

8. The extrusion molding die for a UPVC elbow according to claim 1, characterized in that: The sliding driving mechanism is one of a cylinder and an electric push rod.

9. The extrusion molding die for a UPVC elbow according to claim 1, characterized in that: The rotating driving mechanism includes a motor and a speed reducer connected to the motor.

10. A forming method of a UPVC elbow, characterized in that: Using the extrusion molding mold for UPVC elbows as described in any one of claims 1-7 for processing, includes the following steps: S1. Melting the raw material by a screw extruder and extruding it into the forming cavity. During the injection process, the rotating driving mechanism drives the rotating part to rotate at a constant speed; S2. After the extrusion is completed, a first cooling medium is introduced into the cooling channels on the mold base, and a second cooling medium is introduced into the cooling cavities of the first core mold and the second core mold, and cooling and forming are carried out simultaneously; S3. Starting the rotating driving mechanism to drive the rotating part to rotate, and the rotation speed of the rotating part gradually increases with the cooling time; S4. Starting the sliding driving mechanism to separate the first core mold and the second core mold from the forming cavity, and demolding the product.

Images