What are the mixing principles of an open mill?
Release time:
2020-11-26
What are the mixing principles of an open mill? The mixing process of an open mill generally includes three stages: wrapping, feeding, and mixing. (1) Wrapping Several states of rubber in an open mill: 1—Rubber is difficult to enter the roll gap; 2—Tightly wrapped around the front roll; 3—Forms a bag-like shape after leaving the roll; 4—Viscous flow wrapping the roll (2) Feeding Before the rubber is wrapped around the roll and the compounding agents are added, an appropriate amount of rubber should be kept at the upper end of the roll gap. An appropriate amount of accumulated rubber is a necessary condition for feeding. (3) Mixing Circumferential: Most even mixing; Axial: Uneven; Radial: Least even Factors Affecting Open Mill Mixing 1. Rubber Loading Capacity The rubber loading capacity should be reasonably determined based on the specifications of the open mill and the characteristics of the rubber compound formula. If the capacity is too large, the mixing and dispersion effect will be reduced, the mixing temperature will increase, and scorching may occur, affecting the quality of the rubber compound; if the capacity is too small, it will reduce production efficiency. Formula: V—Rubber loading capacity, L; D—Roll diameter, cm; L—Roll length; 2. Roll Gap The roll gap is generally 4~8mm. Reducing the roll gap increases the shearing effect, but also increases heat generation. 3. Mixing Temperature If the roll temperature is too low, the rubber will be too hard and easily damage the equipment. Increasing the roll temperature helps reduce the viscosity of the rubber and accelerate the mixing and feeding speed, but if the temperature is too high, it is easy to cause the rubber to leave the roll and scorch, making it difficult to operate. The roll temperature is generally maintained between 50~60℃ through cooling. However, when mixing rubber compounds containing high-melting-point compounding agents (such as high-melting-point coumarone resin), the roll temperature needs to be appropriately increased.
What are the mixing principles of an open mill?
The mixing process of an open mill generally includes three stages: wrapping, feeding, and mixing.
(1) Wrapping
Several states of rubber in an open mill
1—Rubber is not easy to enter the roll gap; 2—Tightly wrapped front roll; 3—De-rolled into a bag-like shape; 4—Viscous flow wrapping roll
(2) Feeding
Before the rubber is wrapped and the compounding agents are added, an appropriate amount of rubber should be kept at the upper end of the roll gap. An appropriate amount of piled rubber is a necessary condition for feeding.
(3) Mixing
Circumferential: Most even mixing; Axial: Uneven; Radial: Least even
Influencing factors of open mill mixing
1. Rubber loading capacity
The rubber loading capacity should be reasonably determined according to the specifications of the open mill and the characteristics of the rubber compound formula. If the capacity is too large, the mixing dispersion effect will be reduced, the mixing temperature will increase, and scorching may occur, affecting the quality of the rubber; if the capacity is too small, it will reduce production efficiency.
In the formula, V—rubber loading capacity, L; D—roll diameter, cm; L—roll length;
2. Roll gap
The roll gap is generally 4~8mm. Reducing the roll gap increases the shearing effect, but also increases heat generation.
3. Mixing temperature
If the roll temperature is too low, the rubber will be too hard and easily damage the equipment. Increasing the roll temperature helps reduce the viscosity of the rubber and accelerate the mixing and feeding speed, but if the temperature is too high, it is easy to cause the rubber to de-roll and scorch, making it difficult to operate.
The roll temperature is generally maintained between 50~60℃ through cooling. However, when mixing rubber containing high-melting-point compounding agents (such as high-melting-point coumarone resin), the roll temperature needs to be appropriately increased.
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