Preparation method of HDMP double-wave steel strip reinforced composite pipe

Abstract

The invention relates to the technical field of composite pipe preparation, and particularly discloses a preparation method of an HDMP double-wave steel strip reinforced composite pipe, which comprises the eight steps of raw material treatment, steel strip surface treatment, inner layer matrix extrusion, steel strip coating and winding, outer layer film covering and cooling shaping. Wherein in the step of steel belt coating and winding, a preheated steel belt and molten modified master batches are compounded in an extrusion die head, so that a plastic coating is formed on the surface of the steel belt, and the steel belt with the plastic coating is wound at a spiral angle through a winding cage and pressed outside a pipe base body to form wave crests. Due to the fact that the preheated steel belt has temperature, the plastic layer is not solidified, the non-solidified plastic layer has viscidity, when the steel belt with the plastic layer is wound on the outer layer of the pipe base body, due to the viscidity of the plastic layer, when the contact face of the steel belt and the outer layer of the pipe base body is pressed, stable winding can be achieved, interlayer slippage is not prone to occurring, and the precision of the manufactured pipe is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite pipe preparation, and particularly relates to a method for preparing an HDMP double-wave steel strip reinforced composite pipe. Background Art

[0003] With the increasing demand for environmental protection and high-performance materials, the application research of anhydrous phosphogypsum in various fields has been gradually deepened. Among them, in the field of pipe manufacturing, especially in the preparation of steel strip reinforced composite pipes, anhydrous phosphogypsum has shown great application potential. By compounding anhydrous phosphogypsum with polymer materials such as high-density polyethylene (HDPE), "HDMP" (High Density Modified Polyethylene) anhydrous phosphogypsum composite materials with excellent properties can be prepared.

[0004] The application of this "HDMP" anhydrous phosphogypsum composite material in steel strip reinforced composite pipes not only realizes the resource utilization of industrial by-products, but also significantly improves the performance of the pipes. The addition of anhydrous phosphogypsum enhances the ring stiffness, impact resistance and corrosion resistance of the pipes, making them more suitable for municipal engineering, building water supply and drainage, industrial transportation and other fields. At the same time, due to the relatively low cost of anhydrous phosphogypsum, its application also helps to reduce the production cost of the pipes and improve market competitiveness.

[0005] Currently, in the field of manufacturing steel strip reinforced composite pipes, the production of traditional double-wave structure pipes generally adopts a step-by-step forming process: first, an inner single-wave HDPE pipe is formed by an extrusion molding machine, and after it is cooled and shaped, a steel strip is helically wrapped on the inner surface by a winding device, and finally, the outer layer HDPE is extruded and formed into an outer wave structure for the second time.

[0006] In the published document (a kind of HDPE plastic steel reinforced PP skeleton winding pipe and its production process "CN202110977879.5"), it is recorded that "after the strip body is cooled, it is compounded with the steel strip, and after forming a composite strip, it is drawn to a winding device". Although such a process can realize the basic structure of the composite pipe, there are defects in the insufficient interlayer bonding force.

[0007] The reason is that when the steel strip is wound after the strip is cooled, the polyethylene strip is in a cooled state at this time. When the steel strip is wound on the surface of the polyethylene strip, the steel strip will exert a certain winding pressure on the polyethylene strip. When the polyethylene strip is pressed, interlayer slippage will occur, and the contact surface between the steel strip and the polyethylene is mechanical bonding rather than molten bonding, which will affect the accuracy of corrugation forming, and the inner and outer wave peaks cannot be accurately aligned, significantly weakening the ring stiffness of the pipe.

[0008] In response to the above problems, the prior art is mainly optimized through two types of improvement schemes. Summary of the Invention

[0009] Aiming at the deficiencies of the prior art, the present invention provides a preparation method for HDMP double-wave steel belt reinforced composite pipes, which solves the problem that when the steel belt is wound on the surface of the polyethylene strip, the contact surface between the steel belt and the polyethylene strip undergoes interlayer slip under pressure, affecting the forming accuracy of the corrugated pipe.

[0010] In order to solve the above problems, the technical solution adopted by the present invention is as follows: A preparation method for HDMP double-wave steel belt reinforced composite pipes includes the following steps: S1: Raw material treatment, premix anhydrous phosphogypsum and HDPE particles according to a mass ratio, add a compatibilizer, and granulate in a twin-screw extruder to form a modified masterbatch; S2: Steel belt surface treatment, after the steel belt is leveled by a straightening machine, a laser micro-etching is used to form a reticular groove with a depth of 50 - 80 μm on the surface of the steel belt. The steel belt is pressed into a "U" shape by a forming machine and enters a high-frequency heating device for preheating to 120 - 140 °C; S3: Inner layer matrix extrusion, the modified masterbatch forms a semi-molten state at a temperature of 190 - 205 °C and is then injected into a mold through an extruder to form a smooth inner wall pipe as the pipe matrix; S4: Steel belt coating and winding, the preheated steel belt is compounded with the molten modified masterbatch in an extrusion die head, so that a plastic coating is formed on the surface of the steel belt. The steel belt with the plastic coating is wound and pressed on the outer layer of the pipe matrix at a spiral angle through a winding cage to form a wave crest. During winding, a sensor is used to monitor the wave crest spacing in real time and dynamically adjust the traction speed of the steel belt; S5: Outer layer film covering, an outer layer of molten modified masterbatch is extruded on the outer layer of the steel belt with the plastic coating wound on the pipe matrix to form a film covering layer to obtain a formed pipe; S6: Cooling and shaping, the cooling unit uses a gradient cooling process to cool the formed pipe, and finally forms a steel belt reinforced composite pipe.

[0011] The beneficial effects of this technical solution are as follows: Compared with the existing method of winding the steel belt with the cooled polyethylene strip, in this technical solution, the steel belt is preheated and a plastic layer is coated on the surface of the steel belt. Since the preheated steel belt has a temperature, the plastic layer does not solidify. The non-solidified plastic layer has its own viscosity. When the steel belt with the plastic layer is wound on the outer layer of the pipe matrix, the viscosity of the plastic layer enables the steel belt to be stably wound when the contact surface between the steel belt and the outer layer of the pipe matrix is under pressure and is not prone to interlayer slip. In addition, the etched reticular grooves on the surface of the steel belt can enhance the mechanical bite between the steel belt and the pipe matrix, thereby enhancing the accuracy of the formed pipe.

[0012] Further, in step S1, the anhydrous phosphogypsum and HDPE particles are mixed according to a mass ratio of 1:3.

[0013] Further, the groove spacing in step S2 is 0.8 - 1.2 mm, and the inclination angle is 30 - 45°.

[0014] Further, a maleic anhydride grafted polyethylene transition layer with a thickness of 20 - 30 μm is coated on the surface of the steel strip in step S2. Maleic anhydride grafted polyethylene grafts maleic anhydride molecules onto the polyethylene molecular chain, increasing the polarity of polyethylene. This enables the originally non-polar polyethylene to be better compatible with the polar surface of the steel strip, improving the bonding effect between the two.

[0015] Further, an ultrasonic vibration device with a frequency of 28 kHz and an amplitude of 15 μm is provided at the pressing joint of the steel strip with a plastic coating and the pipe matrix in step S4.

[0016] Further, the gradient cooling adopted in step S6 includes an air-cooling section from 80°C to 60°C → a water mist cooling section from 60°C to 40°C → a vacuum sizing section. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic process flow diagram of an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The following is further detailed through specific embodiments: The embodiment is basically as shown in the Figure 1 accompanying drawings: Embodiment 1 A preparation method of an HDMP double-wave steel strip reinforced composite pipe includes the following steps: S1: Raw material treatment, premix anhydrous phosphogypsum and HDPE particles according to a mass ratio of 1:3, add a compatibilizer, and granulate in a twin-screw extruder to form a modified masterbatch; S2: Steel strip surface treatment, select a 304 stainless steel strip (thickness 0.8 mm), level it with a straightening machine, and then use a 30 kW laser micro-etching to form a reticular groove with a depth of 50 μm on the steel strip surface. The groove spacing is 1.2 mm, and the inclination angle is 45°. A maleic anhydride grafted polyethylene transition layer with a thickness of 20 μm is coated on the steel strip surface. After the maleic anhydride grafted polyethylene transition layer with a thickness of 20 μm is coated and solidified, the steel strip is pressed into a "U" shape by a forming machine and preheated to 120°C in a high-frequency heating device; S3: Inner layer matrix extrusion, the modified masterbatch forms a semi-molten state at a temperature of 190°C and is then injected into a mold through an extruder to form a smooth inner wall pipe as the pipe matrix; S4: Steel strip coating and winding. The preheated steel strip and the molten modified masterbatch are compounded in the extrusion die head, so that a plastic coating is formed on the surface of the steel strip. The steel strip with the plastic coating is wound through the winding cage at a spiral angle and pressed on the outer surface of the pipe substrate to form a wave crest. An ultrasonic vibration device with a frequency of 28 kHz and an amplitude of 15 μm is arranged at the pressing joint of the steel strip with the plastic coating and the pipe substrate. During winding, a sensor is used to monitor the wave crest spacing in real time, and the traction speed of the steel strip is dynamically adjusted; S5: Outer layer film covering. A layer of molten modified masterbatch is extruded on the outer layer of the steel strip with the plastic coating wound on the pipe substrate to form a film covering layer, and the formed pipe is obtained; S6: Cooling and shaping. The cooling unit adopts a gradient: cooling air-cooling section (80 °C → 60 °C) → water mist cooling section (60 °C → 40 °C) → vacuum shaping section to cool down the formed pipe, and finally the steel strip reinforced composite pipe is formed.

[0019] Example 2 A preparation method of an HDMP double-wave steel strip reinforced composite pipe, comprising the following steps: S1: Raw material treatment. The anhydrous phosphogypsum and HDPE particles are premixed according to a mass ratio of 1:3, and a compatibilizer is added, and granulation is carried out in a twin-screw extruder to form a modified masterbatch; S2: Steel strip surface treatment. A 304 stainless steel strip (thickness 0.8 mm) is leveled by a straightening machine, and a reticular groove with a depth of 60 μm is formed on the surface of the steel strip by 30 kW laser micro-etching. The groove spacing is 1.2 mm, and the inclination angle is 40°. A maleic anhydride grafted polyethylene transition layer with a thickness of 20 μm is coated on the surface of the steel strip. After the maleic anhydride grafted polyethylene transition layer with a thickness of 20 μm coated on the surface of the steel strip solidifies, the steel strip is pressed into a "U" shape by a forming machine and preheated to 120 °C in a high-frequency heating device; S3: Inner layer matrix extrusion. The modified masterbatch forms a semi-molten state at a temperature of 190 °C and is then injected into the mold through an extruder to form a smooth inner wall pipe as the pipe substrate; S4: Steel strip coating and winding. The preheated steel strip and the molten modified masterbatch are compounded in the extrusion die head, so that a plastic coating is formed on the surface of the steel strip. The steel strip with the plastic coating is wound through the winding cage at a spiral angle and pressed on the outer surface of the pipe substrate to form a wave crest. An ultrasonic vibration device with a frequency of 28 kHz and an amplitude of 15 μm is arranged at the pressing joint of the steel strip with the plastic coating and the pipe substrate. During winding, a sensor is used to monitor the wave crest spacing in real time, and the traction speed of the steel strip is dynamically adjusted; S5: Outer layer film covering. A layer of molten modified masterbatch is extruded on the outer layer of the steel strip with the plastic coating wound on the pipe substrate to form a film covering layer, and the formed pipe is obtained; S6: Cooling and shaping. The cooling unit adopts a gradient: cooling air-cooling section (80°C → 60°C) → water mist cooling section (60°C → 40°C) → vacuum shaping section to cool down the formed pipe, and finally form a steel strip reinforced composite pipe.

[0020] Example 3 A preparation method of an HDMP double-wave steel strip reinforced composite pipe, comprising the following steps: S1: Raw material treatment. Premix anhydrous phosphogypsum and HDPE particles at a mass ratio of 1:3, and add a compatibilizer, and granulate in a twin-screw extruder to form a modified masterbatch; S2: Steel strip surface treatment. Select a 304 stainless steel strip (thickness 0.8 mm), level it with a straightening machine, and then use a 30 kW laser micro-etching to form a reticular groove with a depth of 80 μm on the steel strip surface, the groove spacing is 1.2 mm, and the inclination angle is 30°. A maleic anhydride grafted polyethylene transition layer with a thickness of 20 μm is coated on the steel strip surface. After the maleic anhydride grafted polyethylene transition layer with a thickness of 20 μm coated on the steel strip surface solidifies, the steel strip is pressed into a "U" shape by a forming machine and preheated to 120°C in a high-frequency heating device; S3: Inner layer matrix extrusion. After the modified masterbatch forms a semi-molten state at a temperature of 205°C, it is injected into a mold through an extruder to form a smooth inner wall pipe as the pipe matrix; S4: Steel strip coating and winding. The preheated steel strip is compounded with the molten modified masterbatch in an extrusion die head, so that a plastic coating is formed on the steel strip surface. The steel strip with the plastic coating is wound and pressed on the outside of the pipe matrix through a winding cage at a spiral angle to form a wave crest. An ultrasonic vibration device with a frequency of 28 kHz and an amplitude of 15 μm is arranged at the pressing joint of the steel strip with the plastic coating and the pipe matrix. During winding, a sensor is used to monitor the wave crest spacing in real time, and the traction speed of the steel strip is dynamically adjusted; S5: Outer layer film covering. Extrude a layer of molten modified masterbatch on the outer layer of the steel strip with the plastic coating wound on the pipe matrix to form a film covering layer to obtain a formed pipe; S6: Cooling and shaping. The cooling unit adopts a gradient: cooling air-cooling section (80°C → 60°C) → water mist cooling section (60°C → 40°C) → vacuum shaping section to cool down the formed pipe, and finally form a steel strip reinforced composite pipe.

[0021] The ring stiffness of the steel strip reinforced composite pipes made in Examples 1-3 was measured and all reached the SN12 grade. When the sensor monitored the pressing of the steel strip and the pipe matrix in Examples 1-3, the change of the wave crest spacing was as shown in Table 1 below:

[0022] From the data in Table 1 above, it can be obtained that when the reticular grooves with an etching depth of 80 μm are formed on the surface of the steel strip, the groove spacing is 1.2 mm, and the inclination angle is 30°, the mechanical biting strength between the steel strip and the pipe matrix is the strongest, so that the peak spacing formed by the steel strip on the outer layer of the pipe matrix is stable at 20 mm, and the steel strip is not prone to slip when winding with the outer layer of the pipe matrix, and the formed pipe has the best precision.

[0023] The above are only embodiments of the present invention, and common knowledge such as specific structures and characteristics well known in the art are not described in detail herein. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent. The protection scope required by this application shall be subject to the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A preparation method of an HDMP double-wave steel strip reinforced composite pipe, characterized in that, It includes the following steps: S1: Raw material treatment. Premix anhydrous phosphogypsum and HDPE particles according to the mass ratio, add a compatibilizer, and granulate in a twin-screw extruder to form a modified masterbatch. S2: Steel strip surface treatment. After the steel strip is leveled by a straightening machine, a reticular groove with a depth of 50 - 80 μm is formed on the steel strip surface by laser micro-etching. The steel strip is pressed into a "U" shape by a forming machine and enters a high-frequency heating device to be preheated to 120 - 140 °C. S3: Inner layer matrix extrusion. The modified masterbatch forms a semi-molten state at a temperature of 190 - 205 °C and is then injected into a mold through an extruder to form a smooth inner wall pipe as the pipe matrix. S4: Steel strip coating and winding. The preheated steel strip and the molten modified masterbatch are compounded in an extrusion die head, so that a plastic coating is formed on the steel strip surface. The steel strip with the plastic coating is wound and pressed on the outer surface of the pipe matrix at a spiral angle through a winding cage to form a wave crest. During winding, a sensor is used to monitor the wave crest spacing in real time, and the traction speed of the steel strip is dynamically adjusted. S5: Outer layer film covering. A layer of molten modified masterbatch is extruded on the outer layer of the steel strip with the plastic coating wound on the pipe matrix to form a film covering layer to obtain a formed pipe. S6: Cooling and shaping. The cooling unit uses a gradient cooling process to cool the formed pipe, and finally a steel strip reinforced composite pipe is formed.

2. The preparation method of an HDMP double-wave steel belt reinforced composite pipe according to claim 1, characterized in that: In the step S1, the anhydrous phosphogypsum and HDPE particles are mixed at a mass ratio of 1:

3.

3. The preparation method of an HDMP double-wave steel strip reinforced composite pipe according to claim 1, characterized in that: In the step S2, the groove spacing is 0.8 - 1.2 mm, and the inclination angle is 30 - 45°.

4. The preparation method of an HDMP double-wave steel strip reinforced composite pipe according to claim 1, characterized in that: In the step S2, a maleic anhydride grafted polyethylene transition layer with a thickness of 20 - 30 μm is coated on the steel strip surface.

5. The manufacturing method of an HDMP double-wave steel strip reinforced composite pipe according to claim 2, characterized in that: In the step S4, an ultrasonic vibration device with a frequency of 28 kHz and an amplitude of 15 μm is arranged at the pressing joint of the steel strip with the plastic coating and the pipe matrix.

6. The preparation method of an HDMP double-wave steel strip reinforced composite pipe according to claim 1, characterized in that: The gradient cooling adopted in the step S6 includes an air-cooling section from 80 °C to 60 °C → a water mist cooling section from 60 °C to 40 °C → a vacuum shaping section.

Images