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Production Method for Silicone Rubber Tube Extrusion Equipment

There are many types of rubber hoses, and silicone rubber hoses are one of them. Based on their structure, silicone hoses can be divided into single‑extrusion hoses and composite hoses. Single‑layer hoses have a relatively simple manufacturing process; during production, we select an appropriate rubber extruder model according to the product’s size. However, since silicone rubber is quite soft, we typically do not use conveyor belts to transport the products during manufacturing. Therefore, the silicone rubber extruder must be elevated during operation. When producing silicone rubber hoses, the die head needs to be designed specifically for each product. For example, when manufacturing single‑layer silicone hoses, we usually employ a T‑die configuration, allowing the extruded rubber to flow vertically downward. A vertical hot‑air vulcanization chamber is then installed directly beneath the die to cure the product. Under gravity, the hose remains free from contact with any surface during vulcanization, thus preventing surface scratches. Because silicone rubber cures readily, the required length of the vulcanization chamber is relatively short. For this reason, elevating the silicone rubber extruder provides an effective solution for curing the finished products. Hebei Shuangda Rubber & Plastic Machinery Co., Ltd. is a modern enterprise integrating research, development, manufacturing, and sales of complete sets of extrusion equipment for rubber, silicone, and plastics. The company’s main products include rubber extruders, rubber hose extrusion lines, three‑component sealing strip extrusion lines, silicone sealing strip production lines, plastic sealing strip production lines, plastic profile extrusion lines, plastic pipe extrusion lines, elastomer extruders, and other extrusion machinery, as well as production equipment for engineering seals, automotive seals, wire and cable applications, air‑conditioning hoses, braided hoses, automotive hoses, waterstop strips, and related products.

2021

05-31

The differences between rubber extrusion equipment and plastic extrusion equipment

Both rubber extruders and plastic extruders are types of extrusion machines, and as we know, most extruders are used to produce extruded products. These two types of equipment are designed according to the characteristics of the materials being processed; therefore, their forming principles differ. Typically, rubber products extruded by a rubber extruder must undergo vulcanization in a curing unit before they can be fully set, whereas plastic extruders achieve product shaping simply by cooling the material. Furthermore, the most significant difference between plastic and rubber extruders lies in their operational requirements: rubber extrusion does not demand high temperatures, making it suitable for low‑temperature processing. Once the rubber is fed into the barrel via the feeding system and heated, its flow properties improve, facilitating easier processing by the extruder screw. Inside the barrel, the screw compresses and mixes the rubber, generating forward extrusion pressure that builds up at the die, ultimately producing the desired final product. For this reason, we employ water‑based temperature control to precisely regulate the barrel and screw temperatures, ensuring accurate thermal management. In contrast, plastic extruders require temperatures sufficient to plasticize the resin—generally above 100°C. Consequently, during plastic production, heating elements are typically used to raise the machine’s temperature, while cooling is achieved through air‑cooling systems to bring the product down to the desired temperature. Thus, different types of plastic extruders rely on distinct extrusion‑forming principles in their manufacturing processes.

2021

06-01

Temperature Control Methods for Extruders at Home and Abroad

The temperature‑control process of an extruder begins by preheating each zone of the barrel to the processing temperature required for the specific compound before normal extrusion commences. Throughout the extrusion cycle, cold material entering the die from the feed port removes heat from the barrel, while shear between the screw and the polymer generates substantial mechanical friction, converting kinetic energy into thermal energy. Consequently, the barrel temperature continuously oscillates between heating and cooling. To maintain a relatively constant temperature, the control system employs auxiliary heating and cooling circuits to mitigate these fluctuations.

2021

08-18

Structure and Operating Process of a Silicone Extruder

In our daily lives, we often encounter silicone products—such as silicone gloves, door and window seals, LED flexible light strips, automotive glass seals, and even silicone items for the human body—making them an inseparable part of our everyday routines. However, most silicone products are manufactured using silicone extruders, particularly silicone tubes, silicone strips, and custom‑shaped silicone sheets, because these machines deliver high production efficiency, large output, and superior quality. Silicone extruders are essential equipment in the silicone industry, playing a critical role in the manufacture of tubing and strip products. Next, we will explore what exactly constitutes a silicone extruder.

2021

09-02

Structural Features of the Rubber Filter Press

2021

09-06

Applications of Pin-Rod Rubber Extruders

Cold-feed rubber extruders are widely used in China’s rubber industry. In pin‑type rubber tube extruders, the pins are inserted directly into annular grooves; under their action, the rubber compound undergoes lateral movement, flow, and rotational motion. The combined effect of these three motions effectively breaks up the core that forms during extrusion. Each time this core passes over a pin, it experiences shear; with each revolution of the screw, the compound is repeatedly divided and sheared by multiple pins, enhancing kneading and accelerating its flow within the screw’s flight grooves, thereby producing high‑quality mixed, kneaded, and plasticized rubber compounds. Thanks to the insertion of pins, mixing, kneading, and plasticization capabilities are significantly improved. Under identical extrusion conditions, the working length of the screw can be shortened by 2–4 times compared with conventional cold‑feed extruders. With a reduced length‑to‑diameter ratio, the residence time of the material inside the barrel is decreased. Almost all rubber extruders now employ pin‑type cold‑feed designs. In bias‑ply tire production, replacing hot‑feed extruders with pin‑type cold‑feed extruders has become a prevailing trend, rapidly gaining momentum. Applications such as tread compound extrusion, various triangular rubbers, and extrusion of different types of rubber have led many manufacturers to adopt pin‑type cold‑feed extruders. Similarly, in hose manufacturing, both inner‑rubber and outer‑rubber extrusions also utilize pin‑type cold‑feed rubber extruders. The rubber hose extruders manufactured by Hebei Shuangda Rubber & Plastics Machinery Co., Ltd. feature a cold‑feed system with non‑leaking feed rollers, coupled with a Changzhou hardened‑gear reducer that drives the feeding mechanism to precisely control the amount of rubber fed, minimizing damage caused by material leakage from multi‑barrel screws and extending equipment lifespan. Pin‑type rubber extruders not only incorporate substantial improvements in screw design but, thanks to the addition of pins on the barrel, also deliver markedly enhanced plasticizing performance, greater compactness of extruded products, and higher extrusion output. Moreover, they operate at lower discharge temperatures, meeting the extrusion requirements of diverse production processes. Concurrently, the optimized screw structure reduces drive power, resulting in a significant decrease in specific energy consumption. Owing to their excellent plasticizing ability, low discharge temperature, and high extrusion capacity, these extruders are enjoying increasingly widespread adoption across the rubber industry.

2021

09-07

What are the components of a rubber extruder?

Rubber extruders and their auxiliary equipment are among the most widely used and critical pieces of machinery in the rubber industry. They are primarily employed for extrusion molding of tire treads, inner tubes, rubber strips, hoses, tapes, and other rubber products. Featuring energy efficiency, high productivity, excellent plasticization, and low‑temperature rubber refining, these machines have significantly expanded their application scope, becoming next‑generation, highly efficient rubber processing equipment. Rubber extrusion equipment is extensively utilized in the production of semi‑finished products such as solid rubber hoses, tire treads, inner and outer layers of rubber hoses, and wire and cable sheathing. It can also be applied to raw rubber compounding, rubber compound filtration, metal wire coating, and more. The typical structure of a rubber extruder comprises a barrel, screw, die (orifice), heating and cooling systems, and a drive mechanism. 1. Barrel During operation, the barrel works in conjunction with the screw, subjecting the rubber compound to the combined action of the barrel’s inner wall and the rotating screw. This ensures that the material moves and mixes under pressure while also serving as a heat‑exchange medium. 2. Screw The screw is the principal working component of the extruder. It generates sufficient pressure to overcome flow resistance and extrude the rubber compound, while simultaneously plasticizing, mixing, and compressing the material to produce a dense, uniform semi‑finished product. 3. Die The die’s function and design vary depending on the specific extrusion process—such as profile extrusion, filter extrusion, mixing, pelletizing, and others. For profile extrusion dies, the primary roles include: converting the spiral motion of the rubber into linear motion; generating the necessary extrusion pressure within the barrel prior to extrusion to ensure a compact semi‑finished product; further homogenizing and plasticizing the rubber; and shaping the extruded semi‑finished product.

2021

09-12

How to choose a sealing strip extruder manufacturer?

Nowadays, there are numerous manufacturers in the seal strip extruder industry—ranging from large to small, numbering in the thousands. Faced with such a wide array of options, how can you make the right choice? How do you select a reliable seal strip extruder manufacturer? Let’s address these questions today. 1. Evaluate the manufacturer’s qualifications When choosing a seal strip extruder manufacturer, check whether they hold a business license, a production permit, and other relevant certifications. Unfortunately, many companies that have entered the market recently lack proper qualifications, oversight, and supporting documentation. As a result, it becomes difficult to ensure that their products meet required standards and maintain consistent quality. 2

2021

09-17

The production process of PVC pipes!

PVC pipe production process: 1. Raw material preparation (PVC + additives) 2. Mixing in a mixer, followed by conveying and feeding 3. Forced feeding 4. Conical twin-screw extruder 5. Extrusion die 6. Sizing sleeve 7. Spray‑vacuum sizing tank 8. Immersion cooling tank 9. Ink printing machine (optional, depending on requirements) 10. Belt‑type haul‑off unit 11. Cutting saw 12. Pipe storage rack The PVC pipe production line primarily uses PVC as the main raw material to manufacture various types of PVC pipes. PVC is a thermoplastic resin produced through polymerization of vinyl chloride under the action of an initiator; it is a homogenized form of polyethylene and exhibits excellent corrosion resistance and heat resistance. Consequently, PVC pipes are widely used for construction piping, sewer and drainage systems, cable protection conduits, and other applications. As one of the most common plastic pipe manufacturing machines, PVC pipe equipment typically consists of an extruder, an extrusion die head, a vacuum sizing tank, a haul‑off unit, a mixer, a cutting saw, and other components. Hebei Shuangda Rubber & Plastics Machinery Co., Ltd. is a modern enterprise integrating research and development, manufacturing, and sales of complete sets of extrusion machinery for rubber, silicone, and plastics. The company’s main products include rubber extruders, rubber hose extrusion lines, three‑layer composite sealing strip extrusion lines, silicone sealing strip production lines, plastic sealing strip production lines, plastic profile production lines, plastic pipe production lines, elastomer extruders, and other extrusion equipment, as well as production machinery for engineering seals, automotive seals, wire and cable applications, air‑conditioning hoses, braided hoses, automotive hoses, waterstop strips, and related products.

2021

09-20

What are the components of a plastic extruder?

In plastic extrusion equipment, the plastic extruder is typically referred to as the main machine, while the auxiliary equipment that works in conjunction with it—such as extrusion molds and downstream processing units—is called the auxiliary machine. The main extruder can be paired with various auxiliary machines for producing pipes, films, monofilaments, flat filaments, strapping bands, extruded nets, sheets, profiles, pellets, cable jackets, and more, forming diverse plastic extrusion production lines capable of manufacturing a wide range of plastic products. Consequently, plastic extrusion machinery remains one of the most widely used types of equipment in the plastics processing industry, both now and in the future. The core component of a plastic extruder is the extrusion system, which consists of an extrusion system, a drive system, and a heating–cooling system. Extrusion System The extrusion system comprises the screw, barrel, hopper, die head, and mold. Through this system, the plastic is plasticized into a uniform melt and continuously forced through the die head by the screw under pressure generated during the process. 1) Screw: This is the most critical component of the extruder, directly influencing its application scope and productivity. It is manufactured from high-strength, corrosion-resistant alloy steel. 2) Barrel: A metal cylinder, typically made of heat- and pressure-resistant alloy steel or composite steel tubing lined with alloy steel. The barrel works in conjunction with the screw to crush, soften, melt, plasticize, degas, and compact the plastic, while continuously and uniformly feeding the molten material into the molding system. Generally, the barrel length is 15–30 times its diameter, ensuring thorough heating and complete plasticization of the material. 3) Hopper: Equipped at its base with a shut-off device for adjusting and interrupting the material flow; side-mounted sight glasses and calibrated measuring devices facilitate monitoring and precise dosing. 4) Die Head and Mold: The die head consists of an inner sleeve made of alloy steel and an outer jacket of carbon steel. Inside the die head, the shaping mold is installed. Its function is to convert the rotating motion of the molten plastic into a steady, parallel linear motion, smoothly guiding the material into the mold cavity and applying the necessary forming pressure. After being plasticized and compacted within the barrel, the plastic passes through a porous filter plate along specific flow channels, enters the die neck, and flows into the shaping mold. Proper coordination between the core and the mold sleeve creates an annular gap whose cross-section gradually narrows, resulting in a continuous, tightly packed tubular coating around the core wire. To ensure proper flow paths inside the die head and eliminate dead zones where plastic might accumulate,分流套筒 (diverting sleeves) are often installed. Additionally, to minimize pressure fluctuations during extrusion, pressure‑equalizing rings may also be employed. The die head further includes mechanisms for correcting and adjusting the mold, allowing easy alignment of the core and mold sleeve concentricity. Based on the angle between the die head’s material flow direction and the screw’s central axis, extruders are classified into oblique-head types (with a 120° angle) and right-angle heads. The die head housing is bolted onto the machine body, while the internal mold features a core holder secured by nuts at the inlet end. The front of the core holder accommodates the core itself, and both the core and its holder have central holes for the core wire to pass through. A pressure‑equalizing ring is mounted at the front of the die head to balance pressure. The extrusion-forming section comprises the mold sleeve and its seat; the position of the mold sleeve can be adjusted via bolts and supports, enabling fine-tuning of its relative position to the core and facilitating uniform control over the thickness of the extruded coating. External heating and temperature‑monitoring devices are also installed on the die head. Drive System The drive system serves to power the screw, supplying the torque and rotational speed required during the extrusion process. Typically, it consists of an electric motor, a reducer, and bearings. Under conditions of similar structural design, the manufacturing cost of a reducer generally increases proportionally with its size and weight. Larger dimensions and heavier construction imply greater material consumption during fabrication, along with larger bearings, thereby driving up production costs. For extruders with identical screw diameters, high-speed, high-efficiency models consume significantly more energy than conventional ones, necessitating double the motor power and correspondingly larger reducer sizes. However, higher screw speeds translate into lower reduction ratios. When comparing reducers of the same size, those with lower reduction ratios exhibit larger gear module sizes, enhancing their load-bearing capacity. Thus, the increase in volume and weight of a reducer does not scale linearly with motor power. If we calculate per unit output, dividing the motor power by the reducer's weight reveals that high-speed, high-efficiency extruders yield lower figures compared to standard extruders. Per unit output, the lower motor power and lighter weight of high-speed, high-efficiency extruders mean that their per-unit manufacturing costs are actually lower than those of conventional extruders. Heating and Cooling Systems Heating and cooling are essential prerequisites for carrying out the plastic extrusion process. 1) Electric heating is commonly used in extruders, including resistance heating and induction heating. Heating elements are installed throughout the machine body, neck, and die head. These systems warm the plastic inside the barrel to reach the temperatures required for the specific process. 2) Cooling systems are designed to maintain the plastic within the desired temperature range. Specifically, they help dissipate excess heat generated by shear friction during screw rotation, preventing overheating that could lead to decomposition, scorching, or difficulties in achieving the desired shape. Barrel cooling is typically achieved through either water cooling or air cooling; smaller and medium-sized extruders usually favor air cooling, whereas larger units often employ water cooling or a combination of both. Screw cooling primarily relies on central water cooling, aiming to improve solid material transport rates, stabilize the extrusion output, and enhance product quality. Meanwhile, cooling at the hopper serves two purposes: first, to strengthen the conveyance of solid materials and prevent plastic granules from becoming sticky and clogging the feed opening due to rising temperatures; second, to ensure the smooth operation of the transmission components.

2021

09-25

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