Roto-molding device for outer lining of metal pipes

Abstract

This invention provides a rotational molding device for lining metal pipe fittings, belonging to the field of operational technology. It solves the problem of uneven wall thickness of the outer surface lining layer in existing hot rotational molding equipment for the inner and outer walls of metal pipes. This rotational molding device for lining metal pipe fittings includes a base, a swing frame, and a powder housing. The swing frame is connected to the base via a horizontally arranged rotating shaft, and the powder housing is connected to the swing frame via a rotary connection structure. A workpiece clamp for holding the metal pipe blank is installed on the powder housing, and a heating component for heating the inner wall of the metal pipe blank is installed on the powder housing or the swing frame. Multiple fins are fixedly connected to the inner wall of the powder housing, arranged circumferentially around the axis of the powder housing, forming powder grooves between adjacent fins. When processing metal pipe fittings with plastic lining using the rotational molding device of this invention, the thickness of the outer lining layer can be controlled by controlling the amount of powder added, thus making it suitable for metal pipe fittings with different wall thicknesses.

Description

Technical Field

[0001] The invention belongs to the field of operation technology and relates to a rotational molding device, in particular to a rotational molding device used for outer lining molding of metal pipe fittings. Background Art

[0002] Metal pipes with plastic lining are widely used in the fields of electricity, chemical industry, petroleum, etc. At present, the following methods are mainly used to line metal pipes with plastic: 1. Hot dip plastic, preheat the metal pipe and immerse it in plastic powder, using the heat of the pipe to make the plastic adhere; 2. Electrostatic spraying, let the plastic powder be charged and adsorbed on the surface of the grounded metal pipe, and then heated to solidify; 3. Extrusion winding, make the extruded plastic strips or belts wrapped around the rotating metal pipe.

[0003] In addition to the above methods, Chinese patent literature also records other methods, such as the process and equipment for hot rotational molding of inner and outer walls of metal pipes (publication number CN101011690A), where the pipe is rolled into the box of the outer wall hot rotational molding machine and the pipe is clamped by the support rods on the two support plates. The motor drives the pipe to rotate, and the high-pressure gas blows up the plastic in the material box to fill the entire box slot, and gradually adsorbs it on the heated pipe to achieve hot rolling of the outer wall of the pipe. This device has problems such as inaccurate temperature control of metal pipes, uneven powder sprinkling speed, uneven wall thickness of the outer surface lining plastic layer, and uncontrollable molding temperature.

[0004] Another example is the hot rotational molding equipment for inner and outer walls of metal pipes (authorization announcement number CN214160316U) recorded in Chinese patent documents. Liquid chemical materials to be added are injected into the liquid tank until the liquid level covers the inner wall of the bottom end of the metal pipe body. After the rapid preheating mechanism preheats the metal pipe body, the variable frequency motor is started to drive the metal pipe body to rotate. When the preheated metal pipe body contacts the liquid chemical material, the liquid chemical material will be plasticized on the inner and outer walls of the metal pipe body. This device has the problem that the wall thickness of the plastic lining layer on the outer surface of the metal pipe is relatively thin.

[0005] Those skilled in the art hope to propose more devices suitable for processing metal pipe fittings with plastic lining to meet the processing requirements of metal pipe fittings from different manufacturers and with different technical requirements. For example, when metal pipe fittings with plastic lining are used in electricity, the thickness of the outer plastic lining is related to the insulation. In other words, in order to meet the use of different working conditions, it is objectively necessary to process metal pipe fittings with plastic linings of different thicknesses. Summary of the invention

[0006] The present invention proposes a rotational molding device for outer plastic lining of metal pipe fittings. The technical problem to be solved by the present invention is how to propose another rotational molding device for outer plastic lining of metal pipe fittings, which is suitable for processing metal pipe fittings with outer plastic linings of different wall thicknesses and improving the uniformity of the wall thickness of the outer surface plastic lining layer.

[0007] The technical problem to be solved by the present invention can be achieved through the following technical solutions: a rotational molding device for outer lining of metal pipe fittings, comprising a machine base, a swing frame and a cylindrical powder shell, wherein the powder shell has a workpiece access door structure; the swing frame and the machine base are connected by a horizontally arranged rotating shaft, and the rotational molding device also includes a swing drive assembly connected to the swing frame and used to drive the swing frame to swing back and forth around the axis of the rotating shaft; the powder shell is connected to the swing frame by a rotary connection structure, and the rotary connection structure makes the axis of the powder shell perpendicular to the axis of the rotating shaft. The invention is arranged that a rotary drive component connected with the powder shell and used for driving the powder shell to rotate around its own axis is installed on the swing frame; a workpiece fixture for clamping the metal tube blank is installed on the powder shell, the clamped metal tube blank is located in the powder shell and the axis of the metal tube blank is arranged parallel to the axis of the powder shell; a heating component for heating the inner wall of the metal tube blank is installed on the powder shell or the swing frame; a plurality of fins are fixedly connected to the inner side wall of the powder shell, and the plurality of fins are circumferentially arranged around the axis of the powder shell, and a powder trough is formed between adjacent fins.

[0008] When metal pipe fittings are processed using a rotational molding device, the metal tube blank of the metal pipe fitting is loaded into the powder material shell through the workpiece access door structure and is clamped and fixed by the workpiece fixture; the powder used for forming the outer lining plastic is loaded into the powder material shell through the workpiece access door structure. The powder is usually located at the bottom of the inner cavity of the powder material shell and can be distributed in one powder material trough or in multiple powder material troughs.

[0009] Manipulate the swing drive component to make the swing frame and the powder shell and other parts swing back and forth, and manipulate the rotary drive component to make the powder shell and other parts rotate, so as to shake the powder evenly. Shaking evenly means that the gravity of the powder per unit length in the axial direction of the powder shell is relatively consistent; in this process, the fins can lift the powder upward, that is, when a powder trough rotates from the lowest position to the highest position, the powder inside gradually slides down naturally, and the powder inside becomes less and less, and part of the powder falls on the outer wall of the metal tube blank. Manipulate the heating component to heat the metal tube blank. After the metal tube blank is heated to a specific temperature, the powder that falls on the outer wall of the metal tube blank is gradually melted and adheres to the outer wall of the metal tube blank. Continuing the above control setting time can make all the powder adhere to the outer wall of the metal tube blank, and after cooling, an outer plastic lining layer is formed outside the metal tube blank.

[0010] Compared with the prior art, the thickness of the outer plastic lining layer can be controlled by controlling the amount of powder added when processing metal pipes with outer plastic linings using the rotational molding device of the present invention, that is, it is suitable for metal pipes with outer plastic linings of different wall thicknesses. The uniformity of the powder sprinkling speed and the uniformity of the wall thickness of the outer plastic lining layer are significantly improved by reciprocating swing, rotation and fin separation. By setting a heating component, the metal pipe can be kept within the temperature range required by the process during the powder sprinkling process, which can not only avoid insufficient melting of the powder due to too low temperature, but also avoid the degradation of the properties of the powder due to too high temperature, thereby improving various properties of the outer plastic lining layer.

[0011] In the above-mentioned rotational molding device for outer lining of metal pipe fittings, any one of the following heating components can be used: First, the heating component includes a support tube and an electric heating element, the support tube is fixedly connected to the swing frame, and part of the electric heating element is installed on the support tube.

[0012] Second, the powder housing has two end plates, and the heating assembly includes a rod-shaped electric heating element, which is installed on the two end plates.

[0013] The third type is that the heating assembly includes a burner installed on a swing frame and a heat dissipation tube installed in a powder housing, the heat dissipation tube is connected to the burner, and the burner is used to heat the heat dissipation tube.

[0014] In the above-mentioned rotational molding device for outer lining of metal pipe fittings, the fins are plates of equal width, the center plane of the fins coincides with the radial line of the powder shell, and the longitudinal line of the fins is arranged parallel to the axial line of the powder shell.

[0015] In the above-mentioned rotational molding device for outer lining of metal pipe fittings, the rotational molding device also includes a heat dissipation fan installed on a swing frame, and a heat dissipation pipe is connected to the heat dissipation fan; an air inlet hole is opened on the end face of the powder shell, and when the heat dissipation pipe is inserted into the air inlet hole, the heat dissipation pipe is connected to the inner cavity of the metal tube blank.

[0016] In the above-mentioned rotational molding device for outer lining of metal pipe fittings, any of the following workpiece clamps can be used. The first type, the workpiece clamp includes a positioning groove on one end plate matching one end of the metal tube blank and a positioning sleeve on the other end plate matching the other end of the metal tube blank; when clamping, one end of the metal tube blank is embedded in the positioning groove, and the positioning sleeve is sleeved on the other end of the metal tube blank.

[0017] Preferably, the middle portion of the end plate is in the shape of a truncated cone, the positioning groove is located on the table surface of the truncated cone, and the outer side of the positioning sleeve is covered with a heat insulation sleeve.

[0018] The second type is that the workpiece clamp includes positioning pins located on two end plates; when clamping, the two positioning pins are respectively inserted into the two end portions of the metal tube blank.

[0019] Preferably, the workpiece clamp further comprises a plurality of manual horizontal clamps mounted on an end plate, and the manual horizontal clamps can be pressed against the end surface of the metal tube blank.

[0020] In the above-mentioned rotational molding device for outer lining of metal pipe fittings, any of the following swivel connection structures can be adopted. The first type, the swivel connection structure includes a bearing, a swivel ring and a swivel support wheel, one end of the swing frame has a stand, the end plate at one end of the powder shell is connected to the stand through a bearing, the other end of the powder shell is fixedly connected with a swivel ring, and the swivel support wheel matched with the swivel ring is installed on the swing frame.

[0021] Preferably, the bearing is located outside the heating assembly, and a heat insulating member is provided between the bearing and the heating assembly.

[0022] The second type, both ends of the swing frame have a vertical frame part, the rotary connection structure includes a rotary shaft rotatably connected to the vertical frame part, the two end parts of the powder shell are arranged one by one corresponding to the two vertical frame parts, and the two end plates of the powder shell are fixedly connected to the rotary shaft on the vertical frame part.

[0023] In the above-mentioned rotational molding device for outer lining of metal pipes, any of the following rotary drive components can be used. First, the rotary drive component includes a second motor, the second motor is mounted on a swing frame, and the main shaft of the second motor is connected to an end plate of the powder housing through a gear transmission.

[0024] Preferably, the powder shell also includes two semi-arched side wall plates, the two side wall plates are connected by a detachable fixed structure, and the end plate and the two side wall plates are also connected by a detachable fixed structure; the rotating ring is divided into two rotating half rings, and the two rotating half rings are arranged in a one-to-one correspondence with the two side wall plates.

[0025] Second, the rotary drive assembly includes a hydraulic motor, and the main shaft of the hydraulic motor is connected to the rotary shaft through a coupling.

[0026] In the above-mentioned rotational molding device for outer lining of metal pipes, any one of the following swing drive components can be used. First, the swing drive component includes a first motor, the first motor is installed on the ground or on a machine base, and the main shaft of the first motor and the swing frame are driven by a gear pair or a sprocket chain.

[0027] Second, the swing drive assembly includes an oil cylinder, a cylinder body of the oil cylinder is connected to the ground or a machine base, and a piston rod is connected to a swing frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 and Figure 2 It is a three-dimensional structural schematic diagram of the rotational molding device from different viewing angles.

[0029] Figure 3 It is a left view structural diagram of the rotational molding device.

[0030] Figure 4 yes Figure 3 Schematic diagram of the cross-sectional structure of AA.

[0031] Figure 5 yes Figure 4 Schematic diagram of the cross-sectional structure of BB.

[0032] Figure 6 It is a schematic diagram of the three-dimensional structure of the rotational molding device after part of the powder shell is hidden.

[0033] Figure 7 It is a schematic diagram of the three-dimensional structure of the powder shell in the rotational molding device in a split state.

[0034] Figure 8 It is a schematic diagram of the three-dimensional structure of a metal pipe with an outer plastic lining.

[0035] In the figure, 100, metal pipe fitting; 100a, metal pipe blank; 100b, outer plastic lining; 1, machine base; 2, swing frame; 2a, stand frame; 3, powder shell; X, axis of powder shell; 3a, side wall plate; 3b, first end plate; 3c, second end plate; 3d, bolt and nut connection structure; 3e, manual clamp; 4, swing drive assembly; 4a, first motor; 4b, sprocket chain; 5, rotary drive dynamic assembly; 5a, second motor; 5b, gear; 6, rotating shaft; 7, bearing; 8, slewing ring; 8a, slewing half ring; 9, slewing supporting wheel; 10, positioning groove; 11, positioning sleeve; 12, manual horizontal clamp; 13, insulation sleeve; 14, support pipe; 15, electric heating element; 16, insulation; 17, fin; 18, powder trough; 19, heat dissipation fan; 20, heat dissipation pipe; 21, counterweight. DETAILED DESCRIPTION

[0036] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0038] In the present invention, unless otherwise clearly defined and specified, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0040] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0041] Embodiment 1: Figures 1 to 7 As shown, the rotational molding device for outer lining of metal pipes includes a machine base 1, a swing frame 2, a powder shell 3, a swing drive component 4 and a rotary drive component 5.

[0042] The base 1 is usually placed on the ground, and the middle part of the swing frame 2 is connected to the base 1 through a horizontally arranged rotating shaft 6, so that the swing frame 2 can swing around the axis of the rotating shaft 6. The swing drive assembly 4 is connected to the swing frame 2 and is used to drive the swing frame 2 to swing back and forth around the axis of the rotating shaft 6. The accompanying drawings of the specification show that the swing drive assembly 4 includes a first motor 4a, and the first motor 4a is installed on the ground or the base 1. The main shaft of the first motor 4a is driven by a gear pair or a sprocket chain 4b to the swing frame 2. According to actual conditions, the swing drive assembly 4 can also adopt other structures. For example, the swing drive assembly 4 includes an oil cylinder, the cylinder body of the oil cylinder is connected to the ground or the base 1, and the piston rod is connected to the swing frame 2.

[0043] The powder shell 3 is cylindrical and is connected to the swing frame 2 through a rotary connection structure. The rotary connection structure allows the axis X of the powder shell to be perpendicular to the axis of the rotating shaft 6. Usually, when the swing frame 2 swings to drive the powder shell 3 to swing synchronously, the axis X of the powder shell swings within a range of ±30° relative to the horizontal plane.

[0044] like Figures 1 to 7 As shown, the powder housing 3 includes two semi-arched sidewalls 3a and two end plates, respectively referred to as the first end plate 3b and the second end plate 3c; the two sidewalls 3a are connected by a detachable fixing structure, and the end plate is also connected to the two sidewalls 3a by a detachable fixing structure. The accompanying drawings of the specification show that the two sidewalls 3a are connected by a bolt and nut connection structure 3d, one end of the two sidewalls 3a is connected to the first end plate 3b by a bolt and nut connection structure 3d, and one end of the two sidewalls 3a is connected to the second end plate 3c by a manual clamp 3e.

[0045] The rotary connection structure includes a bearing 7, a rotary ring 8 and a rotary support wheel 9; one end of the swing frame 2 has a stand 2a, the first end plate 3b is connected to the stand 2a through a bearing 7, the other end of the powder housing 3 is fixedly connected with a rotary ring 8, and the rotary support wheel 9 matched with the rotary ring 8 is installed on the swing frame 2. The rotary ring 8 is fixed on the side wall plate 3a, and the rotary ring 8 is divided into two rotary semi-rings 8a, and the two rotary semi-rings 8a are arranged one by one with the two side wall plates 3a. In the actual production process, the first end plate 3b is usually no longer disassembled, and the side wall plate 3a is placed on the rotary support wheel 9 through the rotary ring 8. The side wall plate 3a is connected to the first end plate 3b through a detachable fixed structure, which is convenient for disassembling and assembling the powder housing 3, thereby improving the convenience of disassembling and assembling the workpiece and improving the processing efficiency. The first end plate 3b of the powder housing 3 is connected to the swing frame 2 through a bearing 7, which not only improves the connection strength and rotation stability; it is also conducive to connecting with the rotary drive assembly 5 and simplifying the structure. In the actual production process, the powder shell 3 can be flexibly disassembled and assembled according to the workpiece, for example, only one side wall plate 3a is removed, only the second end plate 3c is removed, one side wall plate 3a and the second end plate 3c are removed, two side wall plates 3a and the second end plate 3c are removed, etc. The disassembly and assembly of the powder shell 3 of the above parts forms a workpiece picking and placing door structure; the powder shell 3 can improve the convenience of loading and unloading of workpieces and improve processing efficiency.

[0046] The rotary drive assembly 5 is used to drive the powder shell 3 to rotate around its own axis. The attached figure of the specification shows that the rotary drive assembly 5 includes a second motor 5a, and the second motor 5a is installed on the swing frame 2. The main shaft of the second motor 5a is connected to the first end plate 3b through a gear 5b. Other structures can also be adopted according to actual conditions. For example, the rotary drive assembly 5 includes a hydraulic motor, and the main shaft of the hydraulic motor is connected to the center of the first end plate 3b through a coupling. The second motor 5a is located in the vertical frame part 2a, and a counterweight block 21 is installed at the other end of the swing frame 2. By adjusting the weight of the counterweight block 21, the weight consistency of the two ends of the swing frame 2 is improved, thereby reducing the power required to drive the swing drive assembly 4, reducing the manufacturing cost of the rotational molding device and reducing the production cost of the workpiece.

[0047] The workpiece fixture is used to clamp the metal tube blank 100a. The workpiece fixture is installed on the powder shell 3. The clamped metal tube blank 100a is located in the powder shell 3 and the axis of the metal tube blank 100a is parallel to the axis X of the powder shell. Figure 8 As shown, the metal pipe 100 includes a metal pipe blank 100a located inside and an outer plastic lining layer 100b located outside. Figure 4 , Figure 6 and Figure 7As shown, the workpiece clamp includes a positioning groove 10 on the first end plate 3b that matches one end of the metal tube blank 100a and a positioning sleeve 11 on the second end plate 3c that matches the other end of the metal tube blank 100a; when clamping, one end of the metal tube blank 100a is embedded in the positioning groove 10, and the positioning sleeve 11 is sleeved on the other end of the metal tube blank 100a. The workpiece clamp also includes a plurality of manual horizontal clamps 12 installed on the second end plate 3c, and the manual horizontal clamps 12 can press on the end surface of the metal tube blank 100a, thereby limiting the axial movement of the metal tube blank 100a and improving the clamping stability of the metal tube blank 100a.

[0048] like Figure 4 , Figure 6 and Figure 7 As shown, the middle part of the first end plate 3b is in the shape of a truncated cone. This structure can not only make a certain distance between one end of the metal tube blank 100a and the outer edge area of ​​the first end plate 3b, but also reduce the formation of dead zones where powder is easy to accumulate and difficult to accumulate, and improve the consistency of the thickness of the outer lining plastic layer 100b at the end of the metal pipe 100 and the thickness of the outer lining plastic layer 100b at other parts. The outer side of the positioning sleeve 11 is covered with a heat insulation sleeve 13 to reduce the possibility of powder adhering to the outside of the positioning sleeve 11 due to heat.

[0049] The workpiece fixture can be adjusted according to actual conditions. For example, the workpiece fixture includes positioning pins located on the first end plate 3b and the second end plate 3c. When clamping, the two positioning pins are respectively inserted into the two ends of the metal tube blank 100a.

[0050] A heating assembly for heating the inner wall of the metal tube blank 100a is installed on the stand portion 2a of the swing frame 2. The heating assembly includes a support tube 14 and an electric heating element 15. The support tube 14 is fixedly connected to the stand portion 2a, and the electric heating element 15 is installed on the periphery of the support tube 14. The drawings of the specification show that the electric heating elements 15 are two groups, one group of electric heating elements 15 is installed on the support tube 14, and the other group is installed on the stand portion 2a. Although the installation method and the number of electric heating elements 15 can be adaptively adjusted according to the structure of the metal tube blank 100a, the support of the electric heating element 15 by the support tube 14 significantly increases the axial arrangement length of the electric heating element 15, and then the length of the electric heating element 15 is greater than the length of the outer lining plastic layer 100b, and the area to be heated of the metal tube blank 100a is covered by the electric heating element 15, which improves the heating uniformity. The use of electric heating can also effectively improve the cleanliness of the inner wall of the metal tube blank 100a. The above structure allows the metal tube blank 100a to rotate relative to the heating assembly, further improving the heating uniformity. The bearing 7 is located outside the heating assembly, and a heat insulating member 16 is provided between the bearing 7 and the heating assembly, which can effectively protect the bearing 7, extend the maintenance cycle of the bearing 7 and reduce heat loss. The heating assembly can also be installed on the first end plate 3b and the second end plate 3c according to actual conditions.

[0051] like Figure 5 and Figure 7 As shown, a plurality of fins 17 are fixedly connected to the inner side wall of the powder housing 3, and the plurality of fins 17 are arranged circumferentially around the axis X of the powder housing, and a powder groove 18 is formed between adjacent fins 17; the fins 17 are plates of equal width, the center plane of the fins 17 coincides with the radial line of the powder housing 3, and the longitudinal line of the fins 17 is arranged parallel to the axis X of the powder housing. The attached drawings of the specification show that 5 fins 17 are arranged on the inner wall of each side wall plate 3a, thereby forming 10 long strip-shaped powder grooves 18; the number of fins 17 can be adaptively increased or decreased according to actual conditions.

[0052] A heat dissipation fan 19 is also installed at the other end of the swing frame 2, and a heat dissipation pipe 20 is connected to the heat dissipation fan 19; an air inlet hole that can communicate with the inner cavity of the metal tube blank 100a is opened on the second end plate 3c, and the heat dissipation pipe 20 can be installed at the air inlet hole.

[0053] By describing the process of processing the metal pipe 100 using the rotational molding device, the functions and beneficial effects of each component are further explained. The metal tube blank 100a of the metal pipe 100 is clamped by a workpiece fixture, and the powder is placed in the powder tank 18.

[0054] During the process of powder adhering to the metal tube blank 100a, the swing drive component 4 is controlled to make the swing frame 2 and the powder shell 3 and other components reciprocate and swing, the rotary drive component 5 is controlled to make the powder shell 3 and other components rotate, and the heating component is controlled to heat the metal tube blank 100a. The reciprocating swing and rotation of the powder shell 3 can make the gravity per unit length of the powder relatively consistent in the axial direction of the powder shell 3, thereby improving the thickness uniformity of the outer lining plastic layer 100b. When the powder shell 3 rotates, the fins 17 have the function of limiting the sliding of the powder, so as to lift the powder at the bottom of the inner cavity of the powder shell 3 to the top, and in this process, the powder falls naturally under the action of gravity; after the metal tube blank 100a is heated to a specific temperature, the powder sprinkled on the outer wall of the metal tube blank 100a is gradually melted and adhered to the outer wall of the metal tube blank 100a. During the reciprocating swing of the powder shell 3, the axis of the metal tube blank 100a and the falling direction of the powder change in an orderly cycle. During the rotation of the powder shell 3, the outer side of the metal tube blank 100a and the falling powder also change in an orderly cycle. The reciprocating swing and rotation of the powder shell 3 not only improve the thickness uniformity of the outer lining plastic layer 100b, but also make the rotational molding device suitable for processing non-uniform diameter metal tubes, such as Figure 8 The diameter of the right end of the metal pipe 100 is shown to be smaller than that of the left end.

[0055] As the above actions proceed, the powder in the powder shell 3 gradually adheres to the outer wall of the metal tube 100a, the outer plastic lining 100b gradually thickens, and less and less powder can be sprinkled at will.

[0056] After the set time, all the powders adhere to the outer wall of the metal tube blank 100a; the heating component is controlled to stop heating the metal tube blank 100a, and the heat dissipation fan 19 is turned on to supply room temperature air into the metal tube blank 100a through the heat dissipation pipe 20 and the air inlet hole, the metal tube blank 100a and the outer lining plastic layer 100b are quickly cooled, and the outer lining plastic layer 100b is solidified.

[0057] Finally, the swing drive assembly 4 and the rotary drive assembly 5 are closed, and the powder shell 3 is disassembled and the metal pipe 100 is taken out.

[0058] Embodiment 2: The structure and principle of this embodiment are basically the same as those of Embodiment 1. The basic similarities are not described in detail, and only the differences are described. The differences are: both ends of the swing frame 2 have a stand portion 2a, the rotary connection structure includes a rotary shaft 6 rotatably connected to the stand portion 2a, the two end portions of the powder shell 3 are arranged in a one-to-one correspondence with the two stand portions 2a, and the two end plates of the powder shell 3 are fixedly connected to the rotary shaft 6 on the stand portion 2a.

[0059] Embodiment 3: The structure and principle of this embodiment are basically the same as those of Embodiment 1. The basic similarities are not described in detail. Only the differences are described. The differences are as follows: the heating assembly includes a burner installed on the swing frame 2 and a heat dissipation pipe 20 installed in the powder housing 3. The heat dissipation pipe 20 is connected to the burner, and the burner is used to heat the heat dissipation pipe 20.

Claims

1. A rotational molding device for outer lining of metal pipes, characterized in that: The invention comprises a machine base (1), a swing frame (2) and a cylindrical powder shell (3), wherein the powder shell (3) has a workpiece taking-in and putting-out door structure; the swing frame (2) and the machine base (1) are connected via a horizontally arranged rotating shaft (6); the rotational molding device further comprises a swing drive component (4) connected to the swing frame (2) and used for driving the swing frame (2) to swing back and forth around the axis of the rotating shaft (6); the powder shell (3) is connected to the swing frame (2) via a rotary connection structure, wherein the rotary connection structure enables the axis (X) of the powder shell to be arranged perpendicular to the axis (X) of the rotating shaft (6); and a drive assembly (4) connected to the powder shell (3) and used for driving the powder shell (6) is installed on the swing frame (2). 3) a rotary drive component (5) rotating around its own axis; a workpiece fixture for clamping a metal tube blank (100a) is installed on the powder shell (3), the clamped metal tube blank (100a) is located in the powder shell (3) and the axis of the metal tube blank (100a) is arranged parallel to the axis (X) of the powder shell; a heating component for heating the inner wall of the metal tube blank (100a) is installed on the powder shell (3) or the swing frame (2); a plurality of fins (17) are fixedly connected to the inner side wall of the powder shell (3), the plurality of fins (17) are arranged circumferentially around the axis (X) of the powder shell, and a powder trough (18) is formed between adjacent fins (17).

2. The rotational molding device for outer lining of metal pipes according to claim 1, characterized in that: The heating assembly comprises a support tube (14) and an electric heating element (15); the support tube (14) is fixedly connected to the swing frame (2), and part of the electric heating element (15) is mounted on the support tube (14); Or the powder housing (3) has two end plates, the heating assembly comprises a rod-shaped electric heating element (15), and the electric heating element (15) is mounted on the two end plates; Or the heating assembly comprises a burner mounted on the swing frame (2) and a heat dissipation pipe (20) mounted in the powder housing (3); the heat dissipation pipe (20) is connected to the burner, and the burner is used to heat the heat dissipation pipe (20).

3. The rotational molding device for outer lining of metal pipes according to claim 1, characterized in that: The fins (17) are plates of equal width, the center plane of the fins (17) coincides with the radial line of the powder shell (3), and the longitudinal line of the fins (17) is arranged parallel to the axial center line (X) of the powder shell.

4. The rotational molding device for outer lining of metal pipes according to claim 1, characterized in that: The rotational molding device further comprises a heat dissipation fan (19) mounted on the swing frame (2), and a heat dissipation pipe (20) is connected to the heat dissipation fan (19); an air inlet hole is provided on the end surface of the powder shell (3), and when the heat dissipation pipe (20) is inserted into the air inlet hole, the heat dissipation pipe (20) is in communication with the inner cavity of the metal tube blank (100a).

5. The rotational molding device for outer lining of metal pipes according to claim 1, 2, 3 or 4, characterized in that: The powder shell (3) has two end plates, respectively referred to as a first end plate (3b) and a second end plate (3c); the workpiece fixture comprises a positioning groove (10) on the first end plate (3b) matching one end of the metal tube blank (100a) and a positioning sleeve (11) on the second end plate (3c) matching the other end of the metal tube blank (100a); when clamping, one end of the metal tube blank (100a) is embedded in the positioning groove (10), and the positioning sleeve (11) is sleeved on the other end of the metal tube blank (100a); the middle part of the first end plate (3b) is in the shape of a truncated cone, the positioning groove (10) is located on the table surface of the truncated cone, and the outer side of the positioning sleeve (11) is covered with a heat insulation sleeve (13); Or the powder shell (3) has two end plates, and the workpiece clamp comprises positioning pins located on the two end plates; during clamping, the two positioning pins are respectively inserted into the two end portions of the metal tube blank (100a).

6. The rotational molding device for outer lining of metal pipes according to claim 5, characterized in that: The workpiece clamp also includes a plurality of manual horizontal clamps (12) mounted on an end plate, and the manual horizontal clamps (12) can be pressed against the end surface of the metal tube blank (100a).

7. The rotational molding device for outer lining of metal pipes according to claim 1, 2, 3 or 4, characterized in that: The powder housing (3) has two end plates, the rotary connection structure comprises a bearing (7), a rotary ring (8) and a rotary supporting wheel (9), one end of the swing frame (2) has a stand portion (2a), the end plate located at one end of the powder housing (3) and the stand portion (2a) are connected via the bearing (7), the other end of the powder housing (3) is fixedly connected to the rotary ring (8), and the rotary supporting wheel (9) matched with the rotary ring (8) is mounted on the swing frame (2); the bearing (7) is located outside the heating component, and a heat insulating member (16) is provided between the bearing (7) and the heating component; Or the powder housing (3) has two end plates, both ends of the swing frame (2) have a stand portion (2a), the rotary connection structure includes a rotary shaft (6) rotatably connected to the stand portion (2a), the two ends of the powder housing (3) are arranged in a one-to-one correspondence with the two stand portions (2a), and the two end plates of the powder housing (3) are fixedly connected to the rotary shaft (6) on the stand portion (2a).

8. The rotational molding device for outer lining molding of metal pipes according to claim 7, characterized in that: The rotary drive assembly (5) comprises a second motor (5a), the second motor (5a) being mounted on the swing frame (2), and the main shaft of the second motor (5a) being connected to an end plate of the powder housing (3) via a gear (5b); Or the rotary drive assembly (5) comprises a hydraulic motor, and the main shaft of the hydraulic motor is connected to the rotary shaft (6) via a coupling.

9. The rotational molding device for outer lining of metal pipes according to claim 7, characterized in that: The powder housing (3) further comprises two semi-arched side wall plates (3a), the two side wall plates (3a) being connected to each other via a detachable fixing structure, and the end plate and the two side wall plates (3a) being connected to each other via a detachable fixing structure; the slewing ring (8) is divided into two slewing half rings (8a), and the two slewing half rings (8a) are arranged in a one-to-one correspondence with the two side wall plates (3a).

10. The rotational molding device for outer lining of metal pipes according to claim 1, 2, 3 or 4, characterized in that: The swing drive assembly (4) comprises a first motor (4a), the first motor (4a) being mounted on the ground or on a machine base (1), and the main shaft of the first motor (4a) and the swing frame (2) being driven by a gear pair or by a sprocket chain (4b); The swing drive assembly (4) includes a cylinder, a cylinder body of the cylinder is connected to the ground or the machine base (1), and a piston rod is connected to the swing frame (2) Connected.

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