CN101574847A - Device and method for on-line diameter expansion of plastic pipes - Google Patents

Abstract

The invention provides a device and a method for on-line diameter expansion of plastic pipes. The device consists of a cooling water jacket (1), a vacuum sizing sleeve (2) and a cooling vacuum box (3), wherein the vacuum sizing sleeve (2) is arranged at the front end inside the cooling vacuum box (3), and the cooling water jacket (1) is arranged at the front end outside the cooling vacuum box (3). The device of the invention is used in conjunction with pipeline production equipment, cools pipelines immediately after extrusion molding through the cooling water jacket, and then directly expands diameter through the cooling vacuum box and the vacuum sizing sleeve arranged inside the cooling vacuum box, thereby changing a two-time sizing method which needs reheating in the prior art and enabling the plastic pipes to change size and have the memory function of heat shrinkage.

Description

A plastic pipe online diameter expansion device and diameter expansion method

technical field

The invention belongs to the field of on-line processing of plastic pipes, and in particular relates to an online diameter-expanding device and method capable of producing plastic pipes with built-in memory retraction functions.

technical background

At present, domestic pipeline expansion processing mainly focuses on the production and development of heat shrinkable tubes.

There is a method of hot charging for diameter expansion. For example, the Chinese patent application number is 200410010901.5 thermal shrinkage inflation continuous expansion method and expansion device. This type of method has high requirements on the quality of hot air, otherwise water vapor condensation will easily occur, resulting in a drop in inflation pressure and a greatly reduced expansion effect. Moreover, the pressure and temperature of the heat-shrinking air are difficult to control, which also brings uncertainties to continuous production.

Also have the expansion method that adopts vacuum negative pressure adsorption, as the Chinese patent application number is 96200490.1 vacuum type plastics heat-shrinkable tube expansion machine. Chinese patent application No. 97239452.4 is a negative pressure expansion device for heat shrinkable tubes made of polymer materials. However, due to the special design of the equipment used, it is relatively complicated. And it needs to adopt methods such as water bath and oil bath heating, and the heating efficiency is low, thus limiting the improvement of its speed.

Moreover, the diameter expansion of the prior art requires heating (such as hot air or oil bath heating), which consumes a lot of energy, has complicated equipment structure, and the production process is difficult to control and the cost is high.

Contents of the invention

The purpose of the present invention is to overcome the problems existing in the production of existing heat-shrinkable tubes, and to provide a simple online diameter-expanding production device for plastic pipes.

Another object of the present invention is to provide a method for online diameter expansion of plastic pipes according to the device.

In order to realize the purpose of the invention one, the technical scheme adopted is as follows:

An online diameter expansion device for plastic pipes, which is composed of a cooling water jacket, a vacuum calibrating sleeve and a cooling vacuum box, the vacuum calibrating sleeve is installed on the inner front end of the cooling vacuum box, and the cooling water jacket is installed external front end.

The invention is used in conjunction with pipeline production equipment. After the pipeline is extruded, it is cooled by the cooling water jacket, and then the diameter is directly expanded through the cooling vacuum box and the vacuum sizing sleeve arranged inside the cooling vacuum box, which changes the needs of the existing technology. The secondary sizing method of reheating changes the size of the plastic pipe and has the memory function of heat shrinkage.

In the above technical solution, the outer surface of the cooling water jacket is provided with a temperature measuring hole, and the surface temperature of the pipe is measured through the temperature measuring hole to adjust the process to make it reach a reasonable process temperature. The outer surface of the cooling water jacket is also provided with a cooling water hole A water inlet and a water outlet, the water inlet, the water outlet and the inner channel of the cooling water jacket form a cooling water circuit. Cool the extruded pipe through the cooling water circuit.

The cooling vacuum box is in the shape of a box, and a spray water cooling device and vacuum equipment are arranged inside the box. Vacuum equipment is used to adjust the vacuum degree of the cooling vacuum box, and after the diameter is expanded, it is cooled and shaped by a spray water cooling device to become the final expanded diameter tube.

The cooling vacuum box is also equipped with a vacuum gauge for monitoring the vacuum degree. According to the vacuum gauge, the vacuum degree inside the box body can be obtained at any time, so as to adjust the most reasonable vacuum degree value through the vacuum equipment.

In order to realize the purpose of the invention two, the technical scheme adopted is as follows:

An online diameter expansion method for plastic pipes. The heated plastic pipes are sent into the cooling water jacket, cooled by the cooling water channel inside the water jacket, and then the vacuum device of the cooling vacuum box is turned on, and the plastic pipes cooled by the cooling water jacket are Send it into the vacuum sizing sleeve for diameter expansion, and then cool and shape it with the spray water cooling device in the cooling vacuum box to become the final diameter expansion tube.

In the above technical solution, when the cooling water jacket is cooling, it also measures the surface temperature of the plastic pipe through the temperature measuring holes on its surface, so as to adjust the cooling operation parameters to make the plastic pipe reach the required temperature.

In the process of diameter expansion, the present invention also obtains the vacuum degree inside the cooling vacuum box through a vacuum gauge, and adjusts the vacuum degree through vacuum equipment to achieve the required diameter expansion effect.

The present invention can also replace the cooling water jacket according to specific diameter expansion requirements. In the case that the temperature adjustment is not enough to improve the heat shrinkage effect, by replacing the cooling water jacket with a smaller diameter and appropriately increasing the vacuum degree, the degree of heat shrinkage can be increased to meet the design requirements;

In order to optimize the effect of diameter expansion, the cooling water jacket controls the surface temperature of the plastic pipe within the range of 20-50°C.

Compared with the prior art, the present invention has the following beneficial effects:

1. Completely abandon the design idea of heating to expand the diameter. Through the cooperation of the process, the cold expansion method is realized, which is different from the previous practice of forming a tube and then reheating before the diameter reduction process, which greatly simplifies the expansion equipment and makes the expansion process more efficient. Simple;

2. The diameter expansion method of the present invention is flexible, and the surface temperature of the pipe can be monitored through the temperature measuring hole at the rear of the cooling water jacket, thereby ensuring the effect of subsequent diameter expansion and heat shrinkage;

3. The design of the present invention is simple, and most of the devices do not need special design, so it is a common equipment for plastic pipe processing. The equipment has strong versatility, and the operation stability and quality can be effectively controlled. Moreover, the investment cost is low, and the product competitiveness advantage is obvious.

Description of drawings

Fig. 1 is a structural representation of the present invention;

FIG. 2 is a partially enlarged view of FIG. 1 .

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

The production equipment structure diagram of the present invention is as shown in accompanying drawing 1, and device is made up of cooling water jacket 1 at the front end, vacuum sizing sleeve 2 at the rear end and the cooling vacuum box 3 that is used for common plastic processing.

Accompanying drawing 2 is the enlarged view of the circle part in Fig. 1, the inner diameter 11 of the cooling water jacket 1, the outer surface of the cooling water jacket 1 is provided with a water inlet 5 and a water outlet 6, and is also provided with a temperature measuring hole 4 to cool the inside of the vacuum box 3 A vacuum calibrating sleeve 2 is installed, and the inner diameter 21 of the vacuum calibrating sleeve is larger than the inner diameter 11 of the cooling water jacket 1, so this equipment is a diameter expanding equipment. The cooling vacuum box 3 is equipped with a vacuum gauge 7 .

Concrete production steps of the present invention are as follows:

After the pipe comes out of the die, it enters the cooling water jacket 1. After cooling by the cooling water inside the water jacket, after the surface temperature of the pipe reaches a reasonable process temperature, the vacuum pump of the cooling vacuum box 3 is turned on, and the pipe enters the vacuum sizing sleeve 2 for diameter expansion. . Adjust the vacuum to achieve a reasonable diameter expansion effect. After the diameter is expanded, the spray water cooling device in the cooling vacuum box 3 is used for cooling and shaping to become the final expanded diameter pipe.

In the present invention, a temperature measuring hole 4 is provided at the rear of the cooling water jacket 1, which can monitor the surface temperature of the pipe material, thereby ensuring the effects of subsequent diameter expansion and heat shrinkage. If the temperature is too low, it will be difficult to expand the diameter, so the temperature can be increased appropriately. If the temperature is too high and the degree of heat shrinkage is low, the temperature can be lowered. The reasonable pipe surface temperature is between 20-50°C.

The device can also be disassembled, and when the temperature adjustment is not enough to improve the heat shrinkage effect, the cooling water jacket 1 with a smaller diameter can be replaced, and the vacuum degree can be appropriately increased to ensure that the heat shrinkage degree increases to the design requirement.

The plastic pipes applicable to the present invention include PVC-U, PVC-C, PE, PPR, PA, POM and other thermoplastics and rubber elastomers that can be processed by extruders and vacuum setting equipment. The invention not only realizes the online diameter-changing operation of plastic pipes, but also changes the fixed thinking that the plastic pipes must be heated first when changing the diameters of plastic pipes. The equipment investment is low, and it is simple and feasible. The production efficiency is synchronized with the production of plastic pipes, and there is no need to change the conventional plastic pipe formula. The versatility of the equipment is strong, and the competitiveness of the products is also greatly improved.

The present invention will be further described in detail by using two specific examples below.

Embodiment 1: Take the variable diameter of PVC-U pipe Φ15 (outer diameter)×1.5mm (wall thickness) as an example to Φ20×1.4mm, wherein the inner diameter of cooling water jacket 1 is Φ15, and the inner diameter of vacuum calibrating sleeve 2 is Φ20. The production process is as follows:

Temperature measuring point pipe surface temperature Vacuum degree of cooling vacuum box Expansion diameter Degree of heat shrinkage (diameter) 40℃ 0.06MPa Φ20mm Φ18mm

Embodiment 2: PE pipe Φ50 (outer diameter) × 2 mm (wall thickness) is reduced in diameter to Φ55 × 1.8 mm, wherein the inner diameter of the cooling water jacket 1 is Φ50, and the inner diameter of the vacuum setting (expanding) sleeve is Φ55. The production process is as follows:

Temperature measuring point pipe surface temperature Vacuum degree of cooling vacuum box Expansion diameter Degree of heat shrinkage (diameter) 30℃ 0.08MPa Φ55mm Φ50mm

                   

Claims (9)

1. An online diameter expansion device for plastic pipes, characterized in that it consists of a cooling water jacket (1), a vacuum calibrating sleeve (2) and a cooling vacuum box (3), and the vacuum calibrating sleeve (2) is installed in a cooling The inner front end of the vacuum box (3), the cooling water jacket (1) is installed on the outer front end of the cooling vacuum box (3). 2. The plastic pipe online diameter expansion device according to claim 1, characterized in that the outer surface of the cooling water jacket (1) is provided with a temperature measuring hole (4), and a water inlet (5) and a water outlet for cooling water (6), the water inlet (5), the water outlet (6) and the inner channel of the cooling water jacket (1) form a cooling water circuit. 3. The plastic pipe online diameter expanding device according to claim 1, characterized in that the cooling vacuum box (3) is in the shape of a box, and a spray water cooling device and vacuum equipment are arranged inside the box. 4. The plastic pipe online diameter expanding device according to claim 3, characterized in that the cooling vacuum box (3) is also equipped with a vacuum gauge (7) for monitoring the vacuum degree. 5. An on-line diameter expansion method for plastic pipes using the device according to claim 1, characterized in that the heated plastic pipes are sent into the cooling water jacket, cooled through the cooling water channel inside the water jacket, and then the cooling vacuum box is turned on The vacuum device sends the plastic pipe cooled by the cooling water jacket into the vacuum sizing sleeve for diameter expansion, and after the diameter expansion, the spray device in the cooling vacuum box is cooled and shaped to become the final diameter expansion pipe. 6. The online diameter expansion method for plastic pipes according to claim 5, characterized in that when the cooling water jacket is cooling, the surface temperature of the plastic pipe is also measured through the temperature measuring holes on the surface to adjust the cooling operation parameters to bring the plastic tubing to the desired temperature. 7. The method for online diameter expansion of plastic pipes according to claim 5, characterized in that during the process of diameter expansion, the vacuum degree inside the cooling vacuum box is obtained through a vacuum gauge, and the vacuum degree is adjusted to reach the required level through vacuum equipment. Expanding effect. 8. The online diameter expansion method for plastic pipes according to claim 5, characterized in that the cooling water jacket can also be replaced according to specific diameter expansion requirements. 9. The online diameter expansion method for plastic pipes according to claim 5, characterized in that the cooling water jacket controls the surface temperature of the plastic pipes within the range of 20-50°C.

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