Blown film die temperature control structure
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-26
- Publication Date
- 2026-08-11
AI Technical Summary
然而，与电热丝比较，导热油管的控温效果又存在以下明显不足：电热丝各点的发热功率大小是一致的，而导热油管各点的温度是不一致的，即从上游到下游，导热油的温度会逐渐变化，具体是：当利用导热油管进行升温时，随着导热油热量逐渐被吹膜模头吸收，导热油管的温度从导热油管上游到下游逐渐降低；反之，当利用导热油管进行降温时，随着导热油（冷却水）逐渐吸收吹膜模头的热量，导热油管的温度从导热油管上游到下游逐渐升高，这意味着吹膜模头周向各点温度控制效果会产生较大差别，进而导致如前所述的薄膜成品厚度不均匀的问题
[0012]一、本实用新型在每个扇形区域的两条导热油管中，其中一条导热油管的入油口位于顺时针侧而出油口位于逆时针侧，另一条导热油管的入油口位于逆时针侧而出油口位于顺时针侧，两条导热油管的导热油流动方向相反，因此在导热过程中，两条导热油管的温度变化趋势相反，两条导热油管的控温效果刚好可以互相补偿，使得整体的温控效果沿周向基本均匀，使吹膜模头周向各点的温度基本均匀，确保塑料膜厚度比较均匀。
Smart Images
Figure CN224616983U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of plastic blown film equipment, specifically relating to a temperature control structure for a blown film die head. Background Technology
[0002] Plastic film can be produced using plastic blown film equipment. This equipment includes a circular blown film die with an annular extrusion nozzle. During production, molten plastic material is extruded through the annular nozzle of the blown film die, forming an annular film bubble that moves upwards. During this movement, the bubble expands, multiplying in diameter, and then gradually cools and solidifies into an annular plastic film cylinder. This annular plastic film cylinder is then cut into sheet-like plastic films. Throughout this process, the temperature at all points along the circumference of the blown film die must be kept as consistent as possible. If there are significant temperature differences along the circumference, the blown film bubble will exhibit large temperature variations, leading to significant differences in the expansion ratio at each point during subsequent expansion. This, in turn, results in uneven film thickness, affecting the quality of the produced plastic film.
[0003] On the other hand, during the production process, it is necessary to continuously adjust process parameters based on real-time conditions, including adjusting the temperature of the blown film die. The temperature adjustment of the blown film die can be either heating or cooling. The traditional temperature control structure of the blown film die uses a cast aluminum heater with an electric heating wire. When heating is required, heat is transferred through the electric heating wire. When cooling is required, heating can only be stopped by cutting off the power, and natural cooling is relied upon. However, the blown film die (especially the die part of the blown film die) is in a relatively sealed space, and the molten plastic conveyed from the extruder often carries a large amount of shear heat. Therefore, the cooling is slow, and the cooling rate is often unsatisfactory, making it difficult to adapt to the process requirements of the entire production line in a timely manner.
[0004] To address the problem of slow cooling speed, an easy improvement that comes to mind is to use heat transfer oil for temperature control. This involves arranging heat transfer oil pipes inside the blown film die. When heating is required, hotter heat transfer oil is injected into the blown film die, and when cooling is required, cooler heat transfer oil (or cooling water) is injected into the blown film die. This allows for rapid heating and rapid cooling. However, compared with heating wires, the temperature control effect of heat-conducting oil pipes has the following obvious shortcomings: the heating power of heating wires is consistent at all points, while the temperature of heat-conducting oil pipes is inconsistent at all points. That is, the temperature of the heat-conducting oil gradually changes from upstream to downstream. Specifically, when using heat-conducting oil pipes for heating, the temperature of the heat-conducting oil gradually decreases from upstream to downstream as the heat is gradually absorbed by the blown film die head; conversely, when using heat-conducting oil pipes for cooling, the temperature of the heat-conducting oil gradually increases from upstream to downstream as the heat is gradually absorbed by the heat from the blown film die head. This means that the temperature control effect at different points around the blown film die head will vary greatly, leading to the problem of uneven film thickness as mentioned above. Utility Model Content
[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a temperature control structure for blown film die head, which can keep the temperature of each point on the circumference of the blown film die head basically consistent and can quickly adjust and change the temperature.
[0006] The objective can be achieved as follows: A blown film die head temperature control structure, comprising a blown film die head, the blown film die head having an annular extrusion port, characterized in that: the blown film die head is uniformly divided into N fan-shaped regions along the circumference, where N is a natural number; each fan-shaped region is provided with two arc-shaped heat-conducting oil pipes, the center of the arc of each heat-conducting oil pipe being located on the vertical central axis of the blown film die head, the two heat-conducting oil pipes being close together, each heat-conducting oil pipe extending from the first circumferential end of the corresponding fan-shaped region to the second circumferential end; each heat-conducting oil pipe having an oil inlet and an oil outlet; in each fan-shaped region, of the two heat-conducting oil pipes, the oil inlet of one heat-conducting oil pipe is located on the clockwise side and the oil outlet is located on the counterclockwise side, and the oil inlet of the other heat-conducting oil pipe is located on the counterclockwise side and the oil outlet is located on the clockwise side.
[0007] Two heat-conducting oil pipes are arranged vertically in each sector area; the upper layer of the blown film die head consists of N heat-conducting oil pipes, and the lower layer of the blown film die head consists of N heat-conducting oil pipes.
[0008] It is also equipped with a mold temperature controller, which has an oil inlet and an oil return outlet. The oil inlet of the mold temperature controller is connected to a main oil supply pipe, and the oil return outlet of the mold temperature controller is connected to a main oil return pipe. The main oil supply pipe is connected to N branch oil supply pipes. Each branch oil supply pipe is connected to the inlet of a corresponding heat-conducting oil pipe in the upper oil pipe and also to the inlet of a corresponding heat-conducting oil pipe in the lower oil pipe. There are also N branch oil return pipes. The outlet of each heat-conducting oil pipe in the upper oil pipe is connected to a corresponding branch oil return pipe, and the outlet of each heat-conducting oil pipe in the lower oil pipe is also connected to a corresponding branch oil return pipe. Each branch oil return pipe is connected to the main oil return pipe.
[0009] N is a natural number greater than 1 and less than 9.
[0010] When determining the clockwise or counterclockwise direction, the person making the judgment should be positioned above the blown film mold head with their eyes looking downwards.
[0011] This utility model has the following advantages and effects:
[0012] I. In each sector-shaped area of this utility model, one of the heat-conducting oil pipes has its inlet located on the clockwise side and its outlet on the counterclockwise side, while the other has its inlet located on the counterclockwise side and its outlet on the clockwise side. The heat-conducting oil flows in opposite directions in the two pipes. Therefore, during the heat conduction process, the temperature change trends of the two pipes are opposite, and the temperature control effects of the two pipes can compensate for each other, making the overall temperature control effect basically uniform along the circumference. This ensures that the temperature at each point around the blown film die head is basically uniform, thus ensuring that the plastic film thickness is relatively uniform.
[0013] Second, this utility model also retains the advantage of the heat-conducting oil pipe being able to quickly change temperature (heating / cooling), avoiding the disadvantage of the heating wire not being able to cool down quickly. During heating, the mold temperature controller heats the blown film die head through the transfer of oil temperature, and maintains a constant temperature when the design temperature is reached; when cooling is required, heat is conducted through the cooling oil and other media, and the mold temperature controller controls the system temperature, facilitating the heat dissipation of the blown film die head, thereby achieving rapid and controllable temperature control of the blown film die head (including the die opening), which is beneficial for rapid adjustment of the process formula and improvement of film yield and quality. Attached Figure Description
[0014] Figure 1 This is a three-dimensional structural diagram of a specific embodiment.
[0015] Figure 2 This is a cross-sectional structural diagram of a specific embodiment.
[0016] Figure 3 yes Figure 2 A magnified view of a portion of the image, also Figure 4 Schematic diagram of sectional view AA.
[0017] Figure 4 yes Figure 3 Schematic diagram of the cross-sectional structure of the middle CC.
[0018] Figure 5 yes Figure 3 Schematic diagram of the cross-sectional structure of the middle BB.
[0019] Figure 6 This is a schematic diagram showing the connection between the arc-shaped heat-conducting oil pipes located below each sector area and the oil circuit of the mold temperature controller.
[0020] Figure 7 yes Figure 2 A magnified schematic diagram of the structure of part D. Detailed Implementation
[0021] Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 The temperature control structure of the blown film die head shown includes a blown film die head 1, which has an annular extrusion port 10. The blown film die head 1 is evenly divided into four fan-shaped regions along the circumference (the four fan-shaped regions are divided as follows). Figure 4 , Figure 5 As shown by the dashed line, each sector has two arc-shaped heat-conducting oil pipes 2, arranged vertically. The two pipes 2 are close together in each sector. Each arc-shaped heat-conducting oil pipe 2 can be made by bending stainless steel pipes and then casting them into the blown film die head 1 using aluminum. Therefore, the entire blown film die head 1 has a total of four arc-shaped heat-conducting oil pipes 2 located at the top (e.g., ...). Figure 5 The four arc-shaped heat-conducting oil pipes 2 located at the top form the upper oil pipes; the entire blown film die head 1 has a total of four arc-shaped heat-conducting oil pipes 2 located at the bottom (such as...). Figure 4 The four heat-conducting oil pipes 2 in the middle, and the four arc-shaped heat-conducting oil pipes 2 located below form the lower layer oil pipes.
[0022] Figure 4 , Figure 5 As shown, the arc center of each heat-conducting oil pipe 2 is located on the vertical central axis of the blown film die head 1. Each heat-conducting oil pipe 2 extends from the first circumferential end of the corresponding fan-shaped area to the second circumferential end. Each arc-shaped heat-conducting oil pipe 2 is provided with an oil inlet 21 and an oil outlet 22. In the upper and lower heat-conducting oil pipes 2 of each fan-shaped area, the oil inlet 21 of the upper heat-conducting oil pipe 2 is located on the clockwise side, while the oil outlet 22 is located on the counterclockwise side (e.g., ...). Figure 5 As shown), the inlet 21 of the lower heat-conducting oil pipe 2 is located on the counterclockwise side, while the outlet 22 is located on the clockwise side (as shown). Figure 4(As shown). Therefore, in the four arc-shaped heat-conducting oil pipes 2 (upper layer oil pipes) located at the top, the liquid flow direction inside the heat-conducting oil pipes 2 is counterclockwise, as shown. Figure 5 As indicated by the arc-shaped arrow; and in the four lower arc-shaped heat-conducting oil pipes 2 (lower oil pipes), the liquid flow direction inside the heat-conducting oil pipes 2 is clockwise, as shown. Figure 4 As shown by the curved arrow;
[0023] Figure 2 , Figure 3 , Figure 6 , Figure 7 As shown, a mold temperature controller 3 is also provided. The mold temperature controller 3 has an oil inlet 31 and an oil return outlet 32. The oil inlet 31 of the mold temperature controller is connected to a main oil inlet pipe 4, and the oil return outlet 32 of the mold temperature controller is connected to a main oil return outlet 7. The main oil inlet pipe 4 is connected to four branch oil inlet pipes 5. Each branch oil inlet pipe 5 is connected to the inlet 21 of a corresponding heat-conducting oil pipe 2 in the upper oil pipe. Each branch oil inlet pipe 5 is also connected to the inlet 21 of a corresponding heat-conducting oil pipe 2 in the lower oil pipe. There are also four branch oil return outlet pipes 6. The outlet 22 of each heat-conducting oil pipe 2 in the upper oil pipe is connected to a corresponding branch oil return outlet pipe 6. The outlet 22 of each heat-conducting oil pipe 2 in the lower oil pipe is also connected to a corresponding branch oil return outlet pipe 6. Each branch oil return outlet pipe 6 is connected to the main oil return outlet pipe 7.
[0024] In the above embodiments, the blown film die head 1 can be modified to be evenly divided into two, three, six, or eight sector regions along the circumference. Correspondingly, the upper arc-shaped heat-conducting oil pipes 2 can be modified to two, three, six, or eight; the number of lower arc-shaped heat-conducting oil pipes 2 is the same as the number of upper arc-shaped heat-conducting oil pipes 2.
Claims
1. A temperature control structure for a blown film die head, comprising a blown film die head having an annular extrusion port, characterized in that: The blown film die head is evenly divided into N sector-shaped regions along the circumference, where N is a natural number. Each sector-shaped region is equipped with two arc-shaped heat-conducting oil pipes. The center of the arc of each heat-conducting oil pipe is located on the vertical central axis of the blown film die head. The two heat-conducting oil pipes are close together, and each heat-conducting oil pipe extends from the first circumferential end to the second circumferential end of the corresponding sector-shaped region. Each heat-conducting oil pipe has an oil inlet and an oil outlet. In each sector-shaped region, the oil inlet of one heat-conducting oil pipe is located on the clockwise side and the oil outlet is located on the counterclockwise side, while the oil inlet of the other heat-conducting oil pipe is located on the counterclockwise side and the oil outlet is located on the clockwise side.
2. The blown film die head temperature control structure according to claim 1, characterized in that: Two heat-conducting oil pipes are arranged vertically in each sector area; the upper layer of the blown film die head consists of N heat-conducting oil pipes, and the lower layer of the blown film die head consists of N heat-conducting oil pipes.
3. The blown film die head temperature control structure according to claim 2, characterized in that: It is also equipped with a mold temperature controller, which has an oil inlet and an oil return outlet. The oil inlet of the mold temperature controller is connected to a main oil supply pipe, and the oil return outlet of the mold temperature controller is connected to a main oil return pipe. The main oil supply pipe is connected to N branch oil supply pipes. Each branch oil supply pipe is connected to the inlet of a corresponding heat-conducting oil pipe in the upper oil pipe and also to the inlet of a corresponding heat-conducting oil pipe in the lower oil pipe. There are also N branch oil return pipes. The outlet of each heat-conducting oil pipe in the upper oil pipe is connected to a corresponding branch oil return pipe, and the outlet of each heat-conducting oil pipe in the lower oil pipe is also connected to a corresponding branch oil return pipe. Each branch oil return pipe is connected to the main oil return pipe.
4. The blown film die head temperature control structure according to claim 1, 2 or 3, characterized in that: N is a natural number greater than 1 and less than 9.