Open mill

1. The characteristics of the contemporary rubber mixing workshop, CASEND Automation Machinery Co., Ltd.  rubber injection molding machine automation manufacturer centralized; use large-capacity rubber mixing equipment; use twin-screw extruder instead of open mixer to press tablets; implement computer And network remote management; the level of mechanization, linkage and automatic control of the rubber production line is getting higher and higher.

2. The main purpose and classification of the mill

1. Plasticizing, crushing, scrubbing, and tableting of raw rubber;

2. Mixing, tableting and removal of impurities in the rubber;

3. Hot smelting and supply of rubber compound

4. Damage, mixing and tableting of reclaimed rubber.

In addition, it is also widely used in plastic processing and the production of paint and pigment industries.

3. Concepts of plasticizing, mixing, tableting, rubber supply and hot smelting and the differences between them

Plasticizing: the process of converting elastic raw rubber into a plastic state

Mixing: the process of mixing various compounding agents into the raw rubber to make a rubber compound of uniform quality

Pressing: according to the process requirements, the process of pressing the rubber material to a certain width and thickness on the open mill

Glue supply: According to the process requirements, press the rubber material with a certain width and thickness on the open mill and send it to the next process (extrusion, calendering).

Hot smelting: According to the process requirements, the rubber material is processed to a certain temperature and plasticity on the open mill, and then sent to the next process (hot feeding, calendering).

Fourth, the basic structure of the mill, the main difference between several typical mills.

Roller, bearing, frame, gland, transmission equipment, distance adjustment equipment, lubrication system, roller temperature adjustment equipment and emergency braking equipment, etc.

Five, the operating principle of the open mill.

High elasticity and plasticity: The first thing to do is to use an open mill for plasticization. The first step is to cut and knead the rubber through two relatively rotating rollers, so that the original macromolecular chain of the rubber is interrupted, and then the The original elasticity of the rubber material decreases and the plasticity advances, which is conducive to the subsequent processing procedures. Mixing: In the rubber mixing process, the open mixer mainly relies on two relatively rotating rollers to knead and shear the rubber material. Through repeated kneading and the chemical action accompanying the kneading process, the rubber inside The macromolecular chain is broken, so that the various ingredients in the formula are evenly blended, and finally the purpose of rubber mixing is reached.

6, the conditions that the open mill should have to strengthen the rubber mixing function.

1. Make the contact angle of the rubber material greater than the contact angle (φ>α) to bring the rubber material into the roller pitch;

2. Make the front and rear roll speeds (linear speeds) unequal, so that the rubber in the roll gap can be kneaded and sheared vigorously;

3. When mixing rubber, it is necessary to cut and turn the rubber to damage the closed return line of the rubber material and strengthen the dispersion effect of the material;

4. Continuously adjust the roller pitch during the rubber mixing process to change the speed gradient and advance the rubber mixing effect.

7. The method and primary technical characteristics of the open mill specification are indicated.

XK-400: X indicates rubber, K indicates open mill, 400 indicates roller diameter;

SK-400: S indicates plastic, K indicates open mill, 400 indicates roller diameter;

X(S)K-400: X(S) indicates general purpose for rubber and plastics, K indicates open mill, and 400 indicates roller diameter. Regarding some special-purpose open mills, a symbol should be added, such as XKP-400: during which P indicates the rubber breaker; XKA-400: during which A indicates the hot mixer.

8. The concept of transverse pressure and its influencing factors.

The rubber material exerts a radial force (resultant force) on the roller-that is, lateral pressure

(1) The connection between the transverse pressure P and the roller temperature T. When T increases, P decreases; when T decreases, P increases.

(2) Lateral pressure P and roller specification D×L, when D×L increases, P increases; when D×L decreases, P decreases.

(3) The connection between the transverse pressure P and the mixing time t, the longer t is, the smaller P is.

(4) The connection between the amount of accumulated glue and the transverse pressure, (the contact angle can also be used in practice) the larger the α, the larger the P; when the smaller the α, the smaller the P

(5) The connection between rubber properties and transverse pressure. When the hardness of the rubber is greater, the P is greater; when the hardness of the rubber is smaller, the P is smaller.

(6) The connection between rubber temperature and transverse pressure: the lower the temperature, the greater the transverse pressure

(7) The connection between the transverse pressure P and the roll distance e. As for the rubber compound, when e increases, P decreases; when e decreases, P increases.

(8) The influence of roller operating line speed and speed ratio on transverse pressure is more complicated

Nine, the characteristics of the power consumption of the mill.

1. In the rubber mixing process, the power consumption of the drive motor is uneven.

2. Large power consumption.

10. The role, requirements, materials used, structure and classification method of the open mill roller

Function: The roller is the main component of the open mill. In the process of operation, it directly contacts with the rubber material, kneading and shearing the rubber material.

Require:

1. It must have certain mechanical strength and rigidity, and be able to withstand the force of the rubber;

2. The working surface of the roller should have high wear resistance and corrosion resistance, and the surface hardness should not be less than 65° Shore;

3. From the structural point of view, it has a reasonable geometric shape to prevent excessive stress from converging;

4. It has a good heat conduction function, which is convenient for heating and cooling of the rubber;

5. The manufacturing process is simple and the cost is low;

6. The diameter error is 1～0.5mm, and the surface roughness is 3.2～1.6. The factory inspection must ensure that the roll diameter has a positive error.

Material:

Generally, chilled cast iron is used, and the arrangement of the surface layer is hard, wear-resistant, and the hardness of the white layer is not less than 65° Shore

Structure: The roller is mainly composed of a working part with a diameter of D (called a roller body); a supporting part with a diameter of d1, which is called a roller diameter and a transmission part with a diameter of d3.

Classification:

① The classification method is mainly based on the surface shape of the roller. Generally divided into:

a. Lubricate cylindrical roller (cylindrical surface)

b. The waist drum roller is used for the essence of reclaimed rubber,

c. Glue breaking and rubber washing on rollers with grooves,

②According to heating and cooling methods: hollow type, drilling type

③Divided by heating medium: electric heating, steam heating, oil heating, constant temperature water

④According to whether the diameters of the front and rear rollers are the same: same diameter, different diameter

11. The function, orientation, type and lubrication method of the roller bearing of the mill.

Function: To support the roller, so that it can rotate in it. Reduce conflict and throw away, forward transmission power

Orientation: The bearing is sleeved on the shaft diameter at both ends of the roller, and the lower part is supported by the frame. The rear roller bearing is fixed, and the front roller bearing is connected with the pitch adjustment equipment. The frame moves horizontally back and forth.

12. The function, orientation, adjustment plan, classification and specific structure of the roller pitch adjustment equipment of the open mill.

The pitch adjustment plan of various specifications of the mill is generally between 0.1 and 15mm.

Manual, electric, hand-electric, hydraulic

CASEND Automation Machinery Co., Ltd.  mainly produces rubber and plastic machinery automation and peripheral automation equipment. It is a high-tech rubber injection molding machine automation enterprise integrating product development, planning, manufacturing, sales and service. The company’s products are widely used in a variety of tasks, including: home appliance industry, computer and peripheral industry, optoelectronics industry, cosmetics industry, automobile industry, wall clock industry, precision gear industry, PET preform industry, beach table and chair industry, audio-visual music industry, guidance Optical panel industry, communication electronics industry, mobile phone industry, medical supplies industry, medicine packaging industry, food packaging industry...etc. Provide high-quality, high-power, and reasonably-priced automation products for rubber machinery automation. Landline: 0512-36807318 Website: www.casend.net Welcome to come to consult.