阅读说明：本技术 制造pvc-o管材的方法及其扩张装置 (Method for manufacturing PVC-O pipe and expansion device thereof ) 是由 欧阳司晨 李定乾 许宏斌 杨建中 毛埼光 邹同歆 周安民 蒲礼英 陈华 罗毅 童 于 2019-09-26 设计创作，主要内容包括：本发明涉及公开了一种制造PVC-O管材的方法及其扩张装置；其中,所述方法的特点在于,在对采用挤出方法生产的PVC-U胚管进行双向拉伸时,所使用的扩张装置为径向截面积可扩大或缩小的扩张装置；所述的生产PVC-O管材用的扩张装置,其包括拉杆以及由拉杆的轴向移动来控制其展开或收拢的架体部分,当架体部分展开时,架体部分会形成直径逐渐增大的锥体段和直径恒定的圆柱段,且圆柱段连接于锥体段大口径的一端。由于扩张装置的体积是可以扩大或缩小的,所以可以在缩小状态时预先放入PVC-U胚管内,然后使其扩张后再开始取向加工,因此无需预先对PVC-U胚管进行剖管,优化了PVC-O管材连续生产的工艺,降低了取向阶段的难度。(The invention relates to and discloses a method for manufacturing PVC-O tubular product and an expansion device thereof; the method is characterized in that when the PVC-U billet tube produced by the extrusion method is subjected to biaxial tension, the used expansion device is an expansion device with the radial sectional area capable of being expanded or reduced; the expansion device for producing the PVC-O pipe comprises a pull rod and a frame body part which is controlled to be unfolded or folded by the axial movement of the pull rod, wherein when the frame body part is unfolded, the frame body part can form a cone section with gradually increased diameter and a cylinder section with constant diameter, and the cylinder section is connected to one end with large caliber of the cone section. Because the volume of the expansion device can be expanded or reduced, the expansion device can be placed into the PVC-U blank tube in advance in a reduced state, and then the PVC-U blank tube is expanded and then subjected to orientation processing, so that the PVC-U blank tube does not need to be cut in advance, the continuous production process of the PVC-O tube is optimized, and the difficulty in the orientation stage is reduced.)

1. The method for manufacturing the PVC-O pipe is characterized in that when the PVC-U billet tube produced by the extrusion method is subjected to biaxial tension, the used expansion device is an expansion device with the radial sectional area capable of being expanded or reduced.

2. The method for manufacturing PVC-O pipe according to claim 1, wherein the expanding means forms a tapered section with a gradually increasing diameter and a cylindrical section with a constant diameter when the radial sectional area of the expanding means is expanded to the maximum state, wherein the cylindrical section is connected to one end of the tapered section with a larger diameter.

3. The expansion device for manufacturing the PVC-O pipe is characterized by comprising a pull rod (1) and a frame body part (2) which is controlled to be unfolded or folded by the axial movement of the pull rod (1);

when the frame body part (2) is unfolded, the frame body part (2) can form a cone section (a) with gradually increased diameter and a cylinder section (b) with constant diameter, and the cylinder section (b) is connected to one end of the cone section (a) with a large caliber.

4. The stent for manufacturing PVC-O pipes according to claim 3, further comprising a fixed end (31) and a movable end (32); the pull rod (1) penetrates through the fixed end head (31) along the axis and then is fixedly connected with the movable end head (32), and the pull rod (1) can axially and freely move relative to the fixed end head (31); the frame body part (2) is simultaneously kept connected with the fixed end head (31) and the movable end head (32); and when the pull rod (1) drives the movable end (32) to gradually move to one side close to the fixed end (31), the frame body part (2) can be gradually unfolded, and when the pull rod (1) drives the movable end (32) to gradually move to one side far away from the fixed end (31), the frame body part (2) can be gradually folded.

5. Expansion device for the production of PVC-O pipes according to claim 4, characterized in that said frame portion (2) comprises:

the support frames (21) are arranged around the fixed end head (31) at equal intervals, one end of each support frame (21) is hinged with the fixed end head (31), and the other end of each support frame (21) is bent towards the axis direction of the frame body part (2) to form a bending section (211);

the number of the connecting rods (22) is consistent with that of the brackets (21), the connecting rods (22) are arranged around the movable end heads (32) at equal intervals, one end of each connecting rod (22) is hinged with the movable end head (32), and the other end of each connecting rod is hinged with the corresponding bracket (21);

the auxiliary parts (23) are connected among the brackets (21), and the auxiliary parts (23) are made of flexible materials and can be folded or tightened;

wherein, when the frame part (2) is unfolded, the cone section (a) is formed by the part between the bending section (211) and the fixing end (31) and the tightened auxiliary part (23), and the cylinder section (b) is formed by the bending section (211) and the tightened auxiliary part (23).

6. The expanding device for manufacturing the PVC-O pipes as claimed in claim 5, wherein the pull rod (1) is provided with a first fluid channel (11) extending axially in the center, the center of each bracket (21) is provided with a second fluid channel (212) extending axially, and one side of each bracket (21) departing from the axis of the frame body part (2) is provided with a plurality of openings (213) for flowing out of the fluid;

wherein each of said second fluid passages (212) is in communication with said first fluid passage (11).

7. An expanding device for manufacturing PVC-O pipes according to any of the claims 3-6, characterized in that when the frame part (2) is collapsed, the maximum outer diameter of the frame part (2) is smaller than the inner diameter of the pre-processed billet.

Technical Field

The invention relates to the field of PVC-O pipe production, in particular to an expansion device for manufacturing PVC-O pipes.

Background

PVC-O pipe (also called biaxial orientation polyvinyl chloride) is widely applied in the fields of urban water supply and the like in developed countries due to its excellent bearing performance, economy and safety, and is a substitute of traditional PVC-U pipe, PE pipe, nodular cast iron pipe and the like in the water supply field.

The key of the PVC-O pipe forming technology lies in the application of the orientation processing technology, which is to perform radial expansion and axial stretching on the pipe subjected to secondary preheating to ensure that PVC macromolecular chains in the material are orderly arranged in two expansion directions, thereby improving the tensile strength of the material, improving the cracking resistance and crack propagation resistance of the material and ensuring that the material obtains more excellent mechanical properties in the orientation direction. The current production method of the PVC-O pipe comprises the following steps: the PVC-U pipe produced by the extrusion method is axially stretched and radially stretched (namely, biaxially stretched), so that PVC long-chain molecules in the pipe are regularly arranged in a biaxial direction, and the PVC-O pipe with high strength, high toughness, high impact resistance and fatigue resistance is obtained.

Aiming at the Chinese patent with the publication number of CN104162972A, the method disclosed by the patent belongs to a discontinuous intermittent production mode, heated blank tubes are introduced into a mould, high-temperature and high-pressure gas is introduced to expand the blank tubes, and then low-temperature gas is introduced to cool and form, so that oriented tubes are obtained. The two-step process of the patent is complex to realize, has high requirements on the uniformity of wall thickness, needs to cut heads at two ends, and has low utilization rate of raw materials.

The patent discloses a heat shrinkable tube expanding mould, aiming at the Chinese patent with the publication number of CN205167546U, the production mode when the mould is used belongs to a continuous production mode, when in production and processing, a pipe to be processed is heated to a high elastic state, a load is applied to expand the pipe, so that the lower friction force between the inner wall of the heat shrinkable tube and a sizing section of the expanding mould can be realized, the heat shrinkable tube can slide with small resistance, and is rapidly cooled under the condition of keeping the expansion, so that the heat shrinkable tube enters a glass state, and the state can be fixed. And to the chinese patent of publication No. CN205467296U, this patent discloses a PVC-O pipe expansion device, the production mode when using this device also belongs to the continuous production mode, the surface of this device can form uniform water film, playing a role in lubrication, reducing friction, reducing traction force, and at the same time, the water capacity is stronger, the energy consumption is lower and thus the cost is reduced. In the above two patents, although the continuous production mode has high efficiency, the orientation stage is difficult, and the blank tube needs to be cut first and then oriented, which has the disadvantages of high operation difficulty, more influence of human factors, complex equipment and process, low automation degree, low raw material utilization rate, low qualification rate, high labor intensity and the like, so that the method is not very beneficial to automatic production.

Disclosure of Invention

The invention aims to provide a method for manufacturing a PVC-O pipe and an expansion device, and aims to solve the problems that in the continuous production mode, the orientation of a mould is difficult, waste products are more, and the labor intensity is increased.

In order to achieve the above objects, in a first aspect, the present invention provides a method for manufacturing a PVC-O pipe, the method being characterized in that, in biaxially stretching a PVC-U billet produced by an extrusion method, an expansion device having an expanded or reduced radial cross-sectional area is used.

When the expansion device is contracted to the minimum state, the expansion device can be easily plugged into the PVC-U billet tube, and when the expansion device is expanded to the maximum state, the size of the expansion device meets the size requirement of the pre-processed and molded PVC-O.

Further, when the radial sectional area of the expansion device is expanded to the maximum state, the expansion device can form a cone section with gradually increased diameter and a cylinder section with constant diameter, wherein the cylinder section is connected to one end of the cone section with large caliber; the outer diameter of the cylindrical section needs to be ensured to be consistent with the inner diameter of the pre-processed and molded PVC-O pipe.

The method has the beneficial effects that: because the volume of the expansion device is not fixed and can be expanded or reduced, the expansion device can be placed into the PVC-U blank tube in advance in a reduced state, and then the PVC-U blank tube is expanded and then the orientation processing is started, namely, compared with the patents with publication numbers of CN205167546U and CN205467296U, the PVC-U blank tube is not required to be cut in advance, the expansion device is only placed into the blank tube and then expanded and then the orientation processing can be started; therefore, the method optimizes the continuous production process of the PVC-O pipe, reduces the difficulty of the orientation stage, reduces the labor intensity, reduces the rejection rate, shortens the orientation time and obviously improves the automation degree.

In order to achieve the above object in cooperation with the above method, in a second aspect, the present invention provides an expanding device for manufacturing PVC-O pipes, comprising a pull rod and a frame body portion controlled to be unfolded or folded by the axial movement of the pull rod;

when the frame body part is unfolded, the frame body part can form a cone section with the diameter gradually increased and a cylinder section with the constant diameter, and the cylinder section is connected to one end of the large caliber of the cone section.

The expansion device has the beneficial effects that: the frame body part can be unfolded or folded, and can be put into a PVC-U blank tube in advance under the condition of not cutting the tube during folding, and then the frame body part is unfolded to carry out orientation processing; therefore, when the expanding device is used in cooperation with the method, the continuous production process of the PVC-O pipe is optimized, the difficulty of the orientation stage is reduced, the labor intensity is reduced, the rejection rate is reduced, the orientation time is shortened, and the automation degree can be obviously improved.

Furthermore, the expansion device also comprises a fixed end head and a movable end head; the pull rod penetrates through the fixed end head along the axis and is fixedly connected with the movable end head, and the pull rod can axially and freely move relative to the fixed end head; the frame body part is simultaneously kept connected with the fixed end and the movable end; and, when the pull rod orders about the movable end to move to the side that is close to fixed end gradually, the support body part can expand gradually, when the pull rod orders about the movable end to move to the side of keeping away from fixed end gradually, the support body part can draw in gradually.

Further, the frame body part includes:

the support bodies are arranged around the fixed end head at equal intervals, one end of each support body is hinged with the fixed end head, and the other end of each support body is bent towards the axis direction of the support body part to form a bending section;

the number of the connecting rods is consistent with that of the brackets, the connecting rods are arranged around the movable end head at equal intervals, one end of each connecting rod is hinged with the movable end head, and the other end of each connecting rod is hinged with the corresponding bracket;

the auxiliary part is connected among the brackets and made of flexible materials and can be folded or tightened;

when the frame body part is unfolded, the cone section is formed by the part between the bending section and the fixed end head and the tightened auxiliary part, and the cylinder section is formed by the bending section and the auxiliary part.

Furthermore, a first fluid channel extending axially is arranged in the center of the pull rod, a second fluid channel extending axially is arranged in the center of each support, and a plurality of openings for fluid to flow out are formed in one side of each support, which is far away from the axle center of the support body part;

wherein each of said second fluid passageways is in communication with said first fluid passageway.

During orientation processing, fluid (such as gas) can be introduced from the first fluid channel, the fluid can flow out from each opening after passing through the second fluid channel, and the flowing fluid can play a role in reducing friction force so as to reduce resistance when the pipe moves.

Further, when the frame body part is folded, the maximum outer diameter of the frame body part is smaller than the inner diameter of the preprocessed embryonic tube.

Drawings

FIG. 1 is a schematic view of the stent of example 2 in a collapsed state and placed in a PVC-U tube;

FIG. 2 is a schematic view of the stent of example 2 in a deployed state and in the process of orientation;

FIG. 3 is an enlarged view at A in FIG. 2;

FIG. 4 is a schematic view of the stent of example 3 in a collapsed state and placed in a PVC-U tube;

FIG. 5 is a schematic view of the stent of example 3 in an expanded state and undergoing orientation processing;

labeled as: 1-pull rod, 11-first fluid channel, 2-frame part, 21-bracket, 211-bending section, 212-second fluid channel, 213-opening, 22-connecting rod, 23-auxiliary part, 31-fixed end, 32-movable end, 4-PVC-U blank tube, 5-air bag, 6-pull rod, 7-air conveying pipeline, 8-connecting part, a-cone section and b-cylinder section.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced otherwise than as specifically described, and thus the scope of the present invention is not limited by the specific embodiments disclosed below.