JPS593870Y2 - Pre-expanding device for expandable thermoplastic resin particles - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a pre-foaming device for expandable thermoplastic resin particles, which enables quick and reliable pre-foaming work and promotes automation of the work.

Conventionally, in so-called batch-type pre-foaming equipment, in which pre-expanded particles are obtained by heating and expanding a fixed amount of expandable thermoplastic resin particles in a container (or mortar) using a heating medium such as steam, a fixed amount is measured using a weighing hopper. In the past, the resin particles were fed into the container by gravity, but this required a weighing hopper, a spare hopper, etc. to be installed on the container, which tended to make the device larger overall. It takes a lot of time to supply a certain amount of resin particles, and this is one of the reasons why the pre-foaming operation takes a lot of time.

In addition, the actual pre-foaming time using the heating medium in the container must be maintained at an optimal value to obtain good pre-foamed particles, but the expansion ratio may vary depending on various conditions such as the temperature rise inside the container. Because of the difference, it is not possible to perform the optimal pre-foaming operation even if the setting is made so that a constant amount of foam is supplied and the working time is always constant.

Therefore, this invention has been improved to solve the above problems, and its structure is to heat and expand a certain amount of expandable thermoplastic resin particles in a container using a heating medium such as steam to create pre-expanded particles. In the batch-type pre-foaming device to obtain the foam, a weighing hopper is provided at a position adjacent to the container, and a fixed amount of resin particles measured by the weighing hopper is sent to a lower position in the container having an appropriate stirring means and a level meter. It is characterized in that a feed screw is provided between the metering hopper and the metering hopper via a charging shutter.

Next, embodiments of this invention will be described below with reference to the drawings.

1 is a cylindrical container (crude body), 2 is a spare hopper provided adjacent to the container 1 and stores resin particles from the exit loader, 3 is a weighing shutter, and 4 is a spare hopper via the weighing shutter 3. 2 is a weighing hopper connected to the container 1 and located adjacent to the container 1; 5 is a charging shutter on which a timer is set; 6 is a feed screw connected to the weighing hopper 4 via the charging shutter 5; The screw 6 is equipped to feed a fixed amount of expandable thermoplastic resin particles measured by the measuring hopper 4 to the lower part of the container 1.

Inside the container 1, a stirring shaft 12 having a stirring member 11 is transmitted and rotated from a motor 13 via a reducer 14, and a heating medium, air, etc. are allowed to pass through the lower part of the container, but resin particles are not allowed to pass through. Perforated plate 1 with a large number of small holes (preferably about 0.3 to 1.0 mm in diameter)
5 is provided.

16 is a steam chamber formed between the perforated plate 15 and the bottom of the container.

The container 1 is also equipped with a microswitch or tuning fork type level meter 17 that stops the supply of steam when the pre-foamed particles at the upper level rise to a certain level as the pre-foaming progresses. It is provided at a plurality of positions (not shown) at different levels so that it can act even when the pre-expanded particles are biased to one side.

After the level meter 17 operates, drying air is supplied to the container 1.
The piping route is equipped with a solenoid valve (not shown) for timing operation so that the pre-expanded particles can be supplied into the container 1 and discharge air can be supplied when the pre-expanded particles are discharged to the outside of the container 1.

Furthermore, 20 in the figure is a cylinder mechanism for automatically opening and closing the discharge door 21 of the container 1, 22 is a particle aggregate made of a net-like body for collecting the pre-expanded particles to be discharged, and 24 is a gap between the particle aggregate 22. Through the flow rate shutter 23, there is a discharge blower.

In addition, in the above structure, the feed screw 6 is equipped with a large one, for example, the screw diameter is about 100 mmφ, and the rotation speed is kept constant so that 15 kg of resin particles can be fed in 60 seconds. Implement it so that it can operate properly.

Furthermore, in practice, a timer-set input shutter 7 is interposed between the feed screw 6 and the container 1, and the input shutter 7 is closed after a predetermined amount is fed into the container 1. (See Figure 3) and (See Figure 4) 6 may be temporarily stopped; in the latter case, the feed screw 6 is not stopped to prevent backflow.

It is convenient to provide a confirmation window 8 in the case of the feed screw 6 to make it easier to confirm whether the resin particles have fallen from the weighing hopper 4.

The preliminary foaming device according to this invention described above has a preliminary hopper 2.
After opening the weighing shutter 3 between the weighing hopper 4 and the weighing hopper 4 and storing a certain amount of volume in the weighing hopper 4,
The metering shutter 3 is closed, the charging shutter 5 is opened, and a certain amount of resin particles as a raw material are charged into the feed screw 6, and the rotating feed screw 6 feeds the resin particles to a lower position in the container 1.

In this case, if there is also a charging shutter 1 between the container 1 and the feed screw 6, it is in an opened state in advance.

Then, steam is supplied as a heating medium into the container 1 to perform a preliminary foaming action.

When this pre-foaming action progresses and the upper part of the pre-foamed particles hits the level meter 17, the supply of steam is stopped.

After the steam supply is stopped, drying air is supplied to dry the pre-expanded particles so that they do not stick to each other. After drying, the discharge door 21 is opened by the cylinder mechanism 20 and discharge air is supplied to dry the pre-expanded particles. One cycle is completed by actively discharging the water.

Note that the metering shutter 3 is opened at a timing after the heating with steam is completed, and metering for the next fixed amount supply is performed, and resin particles for next use are stored in the metering hopper 4.

The expandable thermoplastic resin particles used in the above implementation are particles of thermoplastic resin such as polystyrene, polyethylene, and polypropylene containing a blowing agent, and the shape of the particles can be arbitrary, but spherical ones are particularly preferable. It is.

According to the above-described pre-foaming device according to this invention, the resin particles pass through the pre-hopper and are weighed at a certain amount in the weighing hopper, and then the input shutter is opened and the resin particles fall to the feed screw, and then the resin particles are transported to the feed screw. Because it is designed to quickly feed the liquid to the lower part of the container, it is a unique batch method that is forced and quick to fill in fixed amounts, unlike the conventional filling method that uses gravity drop. Regardless of the batch system, the filling (supply) time for resin particles is shortened, which in turn helps shorten the pre-foaming work time, and the equipment is far more efficient than the conventional structure in which each hopper is connected to the top of the container. It becomes compact.

Furthermore, the pre-foaming action after supplying the resin particles is not fixed based on time; when the upper pre-foamed particles reach a predetermined position due to the action of a level meter, the heating medium such as steam is automatically turned off. A capacitively sensitive arrangement can be provided, ie, based on the expansion progress of the pre-expanded particles, so that the supply can be stopped.

Therefore, it is possible to eliminate the drawback that batch-type pre-foaming equipment generally has more variation in expansion ratio than continuous-type equipment, and pre-foaming work can be performed without the need for skilled operators. The process can be performed extremely evenly and stably.

Moreover, it has the effect of promoting automation of the preliminary foaming work without causing insufficient heating or overheating, for example.

[Brief explanation of the drawing]

The figures show the embodiment of this invention; Fig. 1 is a front view, Fig. 2 is a side view, and Fig. 3 is a partial cross-sectional view of the case where a charging shutter is also provided between the container and the feed screw. The front view and FIG. 4 are partially sectional front views when the previous closing shutter is not included. 1... Container, 2... Spare hopper, 3... Weighing shutter 4... Weighing hopper, 5... Feeding shutter between weighing hopper and feed screw, 6...
Feed screw, 7... Input shutter between container and feed screw, 11... Stirring member, 12...
・Shaft, 15... Perforated plate, 16... Steam chamber, 1
7...Level meter.

Claims (1)

[Claims for Utility Model Registration] 1. In a batch-type pre-foaming device that obtains pre-foamed particles by heating and expanding a certain amount of expandable thermoplastic resin particles in a container using a heating medium such as steam, A weighing hopper is provided at the weighing hopper, and a feed screw is placed between the weighing hopper and the feeding shutter to feed a fixed amount of resin particles weighed by the weighing hopper to a lower position in a container equipped with appropriate stirring means and a level meter. A pre-foaming device for expandable thermoplastic resin particles, characterized in that the device is equipped with a pre-foaming device for foamable thermoplastic resin particles. 2. The device for pre-expanding expandable thermoplastic resin particles according to claim 1 of the above-mentioned utility model registration, wherein an input shutter is also provided between the feed screw and the container. 3. The pre-foaming device for expandable thermoplastic resin particles according to claim 1, wherein level meters are provided at a plurality of positions with different levels.