A non-blocking pin for a single-screw reciprocating mixer

Abstract

The present invention relates to the technical field of polymer material processing, and discloses a non-blocking pin of a single-screw reciprocating mixer, comprising a shearing piece and a fixing piece sleeved on the shearing piece, wherein a transition piece is arranged on the pin, and the transition piece is used to reduce the blockage of a viscous fluid, and the transition piece is located in a non-smooth transition zone of the pin, and the sum of the angle between the two side surfaces of the transition piece and the angle between the surface of the transition piece and the two side surfaces of the transition piece is in the range of 90° to 120°; the present invention arranges a transition piece on the non-smooth transition zone formed between the fixing piece and the shearing piece of the pin, thereby reducing the aggregation of viscous fluid, thereby reducing the volume of agglomerates formed by viscous fluid, expanding the application range of the single-screw reciprocating pin mixer, and improving product quality; in addition, the present application optimizes the assembly range of the transition piece through simulation tests, and within this assembly range, both the product processing requirements are guaranteed and the processing difficulty and production cost can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material processing, in particular to a non-blocking pin of a single-screw reciprocating mixer. Background Art

[0002] The single-screw reciprocating pin mixer is one of the important equipment in polymer material processing technology. It can shear, split, extrude, stretch and fully mix polymers, polymer additives, polymer fillers and other materials, thereby giving the polymer specific properties. Its structure includes a screw and a barrel. The screw is provided with a threaded element, and the barrel is provided with an inner sleeve and a pin. The equipment can provide axial and radial bidirectional mixing when working. Compared with traditional single-screw mixers and twin-screw mixers, it has the characteristics of good mixing effect, high self-cleaning property, small screw aspect ratio, low extrusion temperature and wide application range.

[0003] Since the first single-screw reciprocating mixer was introduced in 1973, its extrusion output and extrusion speed have increased by 6 times and 4 times respectively, and its application field has become more extensive. For example, publication number US20100284236A1 provides a single-screw reciprocating pin mixer with continuous mixing, which includes a screw shaft, which is provided with four to six groups of radial spiral blades, which are evenly distributed along the circumference, each group consists of a plurality of axially ordered spiral blades, and the ratio of the processing space length to the outer diameter of the spiral shaft ranges from 8 to 12. Compared with traditional machines with a maximum of three spiral blades, the blades enable the quality of dispersion, mixing and homogenization to be continuously maintained. Now, this can be achieved without making the machine itself larger, thereby achieving a significant increase in throughput at a given machine size. Tests conducted for this purpose have shown that the throughput can be increased by 50% compared with traditional machines.

[0004] Another example is publication number CN205735932U, which provides a pin for a reciprocating single-screw mixer, including a barrel seat, an inner sleeve fixedly arranged on the inner side of the barrel seat, a screw rotatably arranged in the inner sleeve, a plurality of spiral ridges distributed on the outer periphery of the screw, spiral ridge grooves formed between adjacent spiral ridges, a plurality of pins fixedly arranged on the barrel seat, the pins pass through the barrel seat and the inner sleeve and are inserted into the spiral ridge grooves, a mounting hole is provided on the pin, a temperature detection device for detecting the temperature of the extrudate in the spiral ridge groove or an additive adding device for adding additives to the extrudate in the spiral ridge groove is provided in the mounting hole, and by arranging the temperature detection device or the additive adding device in the mounting hole of the pin, the mixing extruder can detect the temperature of the extrudate and add additives during operation, and the functionality is relatively strong.

[0005] When using the prior art for actual production, the present application discovered that when the prior art is used to mix a viscous fluid, lumps will remain in the product, the product will be unevenly mixed, and the quality will be poor. The lumps are generated due to the presence of non-smooth transition zones on the pins in the prior art. The non-smooth transition zones refer to the dihedral angles formed between the pin components. During the mixing process, the fluid flow rate of the viscous fluid will decrease when passing through these non-smooth transition zones, causing some unmixed raw materials to be blocked in these non-smooth transition zones and form lumps under the action of pressure. The lumps cannot be broken up and dispersed in the subsequent mixing process, which ultimately causes quality problems in the product. Summary of the invention

[0006] The invention purpose of the present application is to address the problem that the existing technical solutions may cause regional blockage of viscous fluid during the mixing process, and to provide a non-blocking pin for a single-screw reciprocating mixer. By arranging a transition piece on the non-smooth transition zone of the pin, the fluid flow rate of the viscous fluid when flowing through the transition piece plays a role in preventing the blockage of the viscous fluid, thereby reducing the regional blockage formed by the viscous fluid, expanding the application range of the single-screw reciprocating pin mixer, and improving the product quality. In addition, the present application optimizes the assembly form of the transition piece through simulation tests, which not only guarantees the product processing requirements within this assembly range, but also reduces the processing difficulty and reduces the production cost.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A non-blocking pin of a single-screw reciprocating mixer comprises a shearing piece and a fixing piece sleeved on the shearing piece. The transition piece is located in a non-smooth transition zone of the pin and is used to reduce the blockage of a viscous fluid.

[0009] The present invention prevents the viscous fluid from agglomerating during processing by arranging a transition piece at the intersection of the pin components, thereby improving product quality and expanding the application scope of the single-screw reciprocating pin mixer. The pin of the prior art single-screw reciprocating pin mixer has a non-smooth transition zone, which is not suitable for viscous fluids (viscosity range is 2000-5000 When the mixing process is carried out at a speed of 200 Pa•s, the viscous fluid and the pins undergo shear motion, and the fluid manifests itself as turbulence. The physical properties of the turbulent flow, such as temperature, pressure, and density, will change with the change of time and space coordinates, which causes the physical properties of the fluid in this processing space to change irregularly. When the existing technology is used for processing, the flow rate of the viscous fluid in the non-smooth transition zone will decrease, and the processing raw materials will be blocked here at a low fluid flow rate, and then thermal decomposition will occur after high temperature and extrusion; in addition, when the processing raw materials are easily polymerized raw materials such as polyethylene copolymers, polymerization reactions are very likely to occur in the non-smooth transition zone to form indestructible polymers; the present application changes the non-smooth transition zone into a smooth transition zone by setting a transition piece. When the fluid enters this area, the flow rate of the fluid will not be reduced to the flow rate required for blockage, thereby preventing blockage and thermal decomposition of the viscous fluid.

[0010] Preferably, the sum of the angle between the two side surfaces of the transition piece and the angle between the surface of the transition piece and the two side surfaces of the transition piece is in the range of 90°~120°; the present application preferably selects the best assembly form of the transition piece. Since the improvement of processing accuracy will lead to an increase in production costs during the processing, the transition piece is required to be able to control processing costs while meeting processing requirements, and be easy to produce and promote. The present application has found through experiments that when the sum of the angle between the two side surfaces of the transition piece and the angle between the surface of the transition piece and the two side surfaces of the transition piece is in the range of 90°~120°, the transition piece can achieve the technical effect of preventing fluid agglomeration.

[0011] Preferably, the surface of the transition piece is a smooth surface.

[0012] Preferably, the shearing member includes a shearing end, a fixed end and a positioning end, the shearing end performs shearing motion with the viscoelastic fluid, the fixing member is sleeved on the fixed end, the fixing member includes a supporting end and a reinforcing end arranged on the supporting end, the supporting end is sleeved on the fixed end, and the reinforcing end is connected to the side of the fixed end.

[0013] Preferably, a temperature control unit and a material adding unit are provided in the shearing unit, wherein the temperature control unit is used to detect the temperature of the viscoelastic fluid, and the material adding unit is used to add material into the viscoelastic fluid.

[0014] Preferably, the temperature control device is a temperature sensor, and the material adding component is a material adding nozzle.

[0015] Preferably, the pins include long pins and blind pins.

[0016] Preferably, the viscosity of the viscous fluid is 2000-5000 Pa•s.

[0017] Preferably, the viscous fluid is selected from one of a high-voltage cable insulation layer material, a high-voltage cable shielding layer material and a vinyl copolymer.

[0018] Therefore, the present invention has the following beneficial effects:

[0019] (1) The present invention prevents the viscous fluid from agglomerating during processing by providing a transition piece at the intersection of the pin components, thereby improving product quality and expanding the application range of the single-screw reciprocating pin mixer;

[0020] (2) This application has selected the optimal assembly form of the transition piece, under which the transition piece can not only meet the processing requirements but also reduce the processing cost, and is easy to produce and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2 It is a partial cross-sectional view of the transition piece of the present invention.

[0023] Figure 3 It is a schematic diagram of the assembly structure of the present invention.

[0024] Figure 4 It is a pressure distribution diagram of the mixing process fluid of the present invention.

[0025] Figure 5 It is the flow velocity distribution diagram of the mixing process fluid of the present invention.

[0026] In the figure: shearing piece 1, shearing end 101, fixing end 102, positioning end 103, fixing piece 2, supporting end 201, reinforcing end 202, transition piece 3, temperature control piece 4, feeding piece 5, screw 6, inner sleeve 7, barrel shell 8 and fixing through hole 9. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with specific implementation methods.

[0028] In the present invention, unless otherwise specified, all raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

[0029] Embodiment 1:

[0030] like Figure 1As shown, a non-blocking pin of a single-screw reciprocating mixer comprises a shearing piece 1 and a fixing piece 2 sleeved on the shearing piece, the shearing piece comprises a shearing end 101, a fixing end 102 and a positioning end 103, the fixing piece is sleeved on the fixing end, the fixing piece comprises a supporting end 201 and a reinforcing end 202 arranged on the supporting end, the supporting end is sleeved on the fixing end, and the reinforcing end is connected to the side of the fixing end; a transition piece 3 is provided at the junction of the fixing piece and the shearing piece, the transition piece is welded on the non-smooth transition zone of the pin, the surface of the transition piece is a smooth curved surface, a temperature control piece 4 and a feeding piece 5 are provided in the shearing piece, the temperature control piece is a temperature monitoring sensor, and the feeding piece is a feeding nozzle.

[0031] like Figure 2 As shown, the angle between the two side surfaces of the transition piece is C, the angle formed by the transition piece surface and the surface of one side of the transition piece is A, the angle formed by the transition piece surface and the surface of the other side of the transition piece is B, and the sum of the angle A, the angle B and the angle C ranges from 90° to 120°.

[0032] like Figure 3 As shown, a schematic diagram of the assembly structure of a non-blocking pin of a single-screw reciprocating mixer includes a barrel and a screw 6 rotatable in the barrel, the barrel includes an inner sleeve 7 and a barrel shell 8 sleeved outside the inner sleeve, four pins distributed along the axial direction of the barrel are inserted into the barrel, the shear end is located in the space between the inner sleeve and the screw, the inner sleeve is provided with a fixing through hole 9 matching the fixing piece, the fixing piece is located in the fixing through hole, the barrel shell is provided with a positioning through hole, the fixing end passes through the fixing through hole and the positioning through hole in sequence, and the positioning end is located outside the positioning through hole.

[0033] Embodiment 2:

[0034] The non-blocking pin in Example 1 is applied in the mixing process of high-voltage cable shielding layer materials.

[0035] The mixing process conditions include: raw material components, processing temperature of 125°C, processing line speed of 1.5 m / s, and fluid viscosity of the mixed material of 2000 Pa•s;

[0036] The mixer dimensions include: the processing barrel length diameter is 100 mm, and the screw speed is 400 rpm.

[0037] Embodiment 3:

[0038] The non-blocking pin in Example 1 is applied in the mixing process of the high-voltage cable insulation layer material.

[0039] The mixing process conditions include: the high-voltage cable shielding layer material contains 35% carbon black, the processing temperature is 125°C, the processing line speed is 1.5m / s, and the fluid viscosity of the mixed material is 2000Pa•s;

[0040] The mixer dimensions include: the processing barrel length diameter is 100 mm, and the screw speed is 400 rpm.

[0041] Embodiment 4:

[0042] The non-blocking pins in Example 1 are used in the vinyl material compounding process.

[0043] The mixing process conditions include: the raw material component is low-density polyethylene, the processing temperature is 110°C, the processing line speed is 1.8m / s, and the fluid viscosity of the mixed material is 1000Pa•s;

[0044] The mixer dimensions include: the processing barrel length diameter is 100 mm, and the screw speed is 400 rpm.

[0045] Comparative Example 1:

[0046] Compared with Example 1, the high-voltage electric shielding layer material is mixed and processed using the pins in the prior art, and the pins are not provided with transition pieces. The other mixing conditions are the same as those in Example 2.

[0047] Comparative Example 2:

[0048] Compared with Example 1, the high-voltage cable insulation layer material is mixed and processed using the pins in the prior art, the pins are not provided with transition pieces, and the other mixing conditions are the same as those in Example 3.

[0049] Comparative Example 3:

[0050] Compared with Example 1, the vinyl material is mixed and processed using the pins in the prior art, and the pins are not provided with transition pieces. The other mixing conditions are the same as those in Example 4.

[0051] Simulation test:

[0052] The dimensions of the mixers of Examples 2 to 4 and Comparative Examples 1 to 3 were imported into the 3D modeling software UG to build a model, and then the model was imported into the workbench solution module. A simulation test was then performed according to the corresponding mixing process. The flow field pressure, technical inner wall pressure, and transition zone fluid flow rate during the simulation process were recorded. The recorded results are shown in Table 1. The mixing process fluid pressure is shown in Table 1. Figure 4 As shown, the mixing process fluid flow rate is Figure 5 As shown;

[0053] Table 1 Simulation results

[0054]

[0055] When the flow field pressure is greater than 800 kPa, the flow velocity in the transition zone is less than 2×10 -2m / s, fluid blockage will occur, and the greater the flow field pressure and the smaller the fluid flow rate, the more obvious the blockage phenomenon. It can be seen from the results in Table 1 that when the technical solution of the present invention and the prior art solution are used to simulate the processing of high-voltage cable shielding layer materials, the flow field pressure and technical inner wall pressure of Examples 2 to 3 are lower than the minimum flow field pressure when agglomerates can be formed, and the flow rate in the transition zone is higher than the maximum flow rate when agglomerates can be formed. The flow field pressure and technical inner wall pressure of Comparative Examples 1 to 3 are higher than the minimum flow field pressure when agglomerates can be formed, and the flow rate in the transition zone is lower than the maximum flow rate when agglomerates can be formed, indicating that the technical solution provided in the present application can prevent fluid blockage and agglomeration when mixing and processing raw materials with high fluid viscosity.

Claims

1. A non-blocking pin for a single-screw reciprocating mixer, comprising a shearing member (1) and a fixing member (2) sleeved on the shearing member, characterized in that: The shearing member comprises a shearing end (101), a fixing end (102) and a positioning end (103); the shearing end (101) performs shearing motion with a viscoelastic fluid; the fixing member (2) is sleeved on the fixing end (102); the fixing member (2) comprises a supporting end (201) and a reinforcing end (202) arranged on the supporting end; the supporting end (201) is sleeved on the fixing end (102); the reinforcing end (202) is connected to a side surface of the fixing end (102); a transition member (3) is provided at the junction of the fixing member (2) and the shearing member (1); the transition member (3) is used to prevent viscous fluid from blocking; the sum of the angle between the two side surfaces of the transition member (3) and the angle between the surface of the transition member and the two side surfaces of the transition member is in the range of 90° to 120°.

2. The non-blocking pin of a single-screw reciprocating mixer as claimed in claim 1, characterized in that: The surface of the transition piece (3) is a smooth surface.

3. The non-blocking pin of a single-screw reciprocating mixer as claimed in claim 1, characterized in that: A temperature control unit (4) is provided in the shearing member, and the temperature control unit is used to detect the temperature of the viscoelastic fluid.

4. The non-blocking pin of a single-screw reciprocating mixer as claimed in claim 3, characterized in that: The temperature control unit (4) is a temperature monitoring sensor.

5. The non-blocking pin of a single-screw reciprocating mixer as claimed in claim 1, characterized in that: A material adding piece (5) is also provided in the shearing piece, and the material adding piece is used to add material into the viscoelastic fluid.

6. A non-blocking pin for a single-screw reciprocating mixer as claimed in claim 5, characterized in that: The material adding component (5) is a material adding nozzle.

7. The non-blocking pin of a single-screw reciprocating mixer as claimed in claim 1, characterized in that: The viscosity of the viscous fluid is 2000-5000 Pa·s.

8. A non-blocking pin for a single-screw reciprocating mixer as claimed in claim 7, characterized in that: The viscous fluid is selected from any one of a high voltage cable insulation layer material, a high voltage cable shielding layer material and a vinyl copolymer.

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