JPS582068B2 - Remotely controlled injector for mixing head of chemical components feeding into mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention A remotely controlled injector is disclosed for injecting reactive chemical components supplied under high pressure into the mixing chamber 2 of a mixing head 1 and dispensing the mixture into a mold 1a; The injectors 7, 8 are equipped with needle valves connected to a sliding control piston 21, with one end of the control piston applying a thrust of the chemical component to be injected, and the other end of the control piston applying a thrust of the control fluid supplied at a constant pressure. Apply thrust.

The present invention relates to a remotely controlled injector for a mixing head of reactive chemical components, particularly reactive polyurethane materials, which are fed into molds.

As is well known, the mixing head in question consists of a mixing chamber, either open or in communication with a mold, into which the chemical components are fed under pressure and at high speed and separated into fine individual particles. Small jets of atomized material are formed which impinge in a small space and are thoroughly mixed before being fed into the mold.

Injection of the components into the mixing chamber is usually carried out by an injection valve (hereinafter simply referred to as an injector), in which a needle valve is usually mounted by a spring in the direction of an injection nozzle, and this nozzle is inserted into the mixing chamber. Open to.

The force provided by the biasing spring can be adjusted appropriately by varying its compression force to balance the thrust of the chemical component on the needle valve and to obtain the desired injection pressure value.

When using an injector of the type described above, in order to ensure a constant stoichiometric ratio in the mixing of the components, it is necessary to The problem arises of ensuring that the injection of a single component always takes place at a constant pressure.

The use of balancing springs in known types of valves still does not satisfactorily solve this problem and cannot be adjusted by remote control.

In fact, in known valves it is necessary to act directly on the biasing spring, and furthermore the spring is not able to provide a completely constant pressure-balancing force.

On the other hand, it is extremely important to make and maintain accurate settings of the injector in order to achieve the desired feed pressure of the chemical components and ensure sufficient atomization of the chemical components injected into the mixing chamber. be.

In practice, it has been found that by keeping the injection conditions of the single components into the mixing chamber always constant and unchanged, the quality of the mixture can be improved and defects in the product or molded article can thus be avoided.

The object of the invention is to provide an injector for a mixing head of reactive chemical components of the type described above, with which the above-mentioned problems can be overcome, i.e. the injection valve can be set remotely at a constant pressure value. .

A further object of the invention is to provide an injector as described above, which is capable of automatically adjusting to a predetermined injection pressure value, irrespective of any changes in the operating conditions downstream of the injector, for example due to accidents during the mixing or circulation process of chemical components. It is to be.

A further object of the invention is to provide an injector for a mixing head as described above, which can be operated by remote control to effect circulation of chemical components at different pressure values.

According to the present invention, there is provided a remotely controlled injector for use in a mixing head for feeding chemical components into a mold, in which the mixing head comprises a mixing chamber and one side wall of the injector comprises a mixing chamber.
The injector comprises a body having a cylindrical cavity with a nozzle at one end, and the cavity communicates with a large injection hole in the mixing chamber through the nozzle. and a needle valve is provided in the cavity of the injector so as to be axially movable from a closed position to a balanced open position, the needle valve being axially movable within the cavity. It is supported at the end of the control piston and is characterized in that a thrust of the chemical component being supplied is applied to one side of the control piston and a counter-thrust of control fluid having a constant pressure value is applied to the other side.

Hereinafter, the injector of the present invention will be explained in more detail with reference to the accompanying drawings.

Figure 1 shows mixing the reactive chemical components and depositing the mixture into mold 1.
1 shows a typical head 1 for feeding A;

This head consists, as is known, of a mixing chamber 2, which can be of any desired shape, and an outlet opening 3 which directs the mixture in the direction of the mold 1A, and a plug which slides axially within the chamber 2. A cleaning member 4 in the form of .

This member 4 is moved from an advanced position by means of a cylinder 5 or other control mechanism to close the mixture outlet opening 3 and at the same time prevent single chemical components from entering the mixing chamber 2. and a retracted position that opens the component injection aperture.

These apertures are injectors 7 and 8 of a single chemical component.
It is provided on a part of the side wall of the chamber 2 in correspondence with the above.

Each injector 7 and 8 is connected to, for example, a tank 12 by piping 9 and 10, as shown in FIG. 2 and described below.
The injectors 7 and 8 each have a control section connected to the injectors 7 and 8, and each control section of the injectors 7 and 8 can be supplied with control fluid at a constant pressure value.

Reference numeral 13 in FIG. 1 indicates a general control fluid pressure regulating device.

FIG. 2 shows an enlarged longitudinal section of one of the injectors, for example the injector of FIG.

As can be seen in FIG. 2, the injector consists of a body 14 screwed into a suitable housing, for example in the body 1 of the mixing head, defining a cylindrical cavity 15 at one end and a wall of said mixing chamber. A tapered nozzle 16 is provided for injecting the chemical components into the mixing chamber through the aperture at 17 .

Reference numeral 18 in FIG. 2 designates a chamber of annular or similar shape, connected on one side to the component supply duct 19 and on the other side via a radial passage 20 to the internal cavity 15 of the injector and the nozzle. Connect to 16.

A cylindrical cavity 15 in the injector starts from a radial feed channel 20 for the component and extends rearwardly over a length 15a into which a support piston 21 for the needle valve slides.

This valve consists of a conical part 22 and a terminating cylindrical end part 23 with a diameter corresponding to the smallest diameter of the injection nozzle 16.

The needle valve 22, 23 and piston 21 assembly is axially centered such that the needle valve 22, 23 closes the nozzle 16 and prevents components from being delivered into the mixing chamber from an advanced position. is movable to a retracted position in which it opens an injection nozzle, which together with the injection nozzle defines an annular passage whose cross-sectional area determines the pressure value for supplying and injecting the components into said mixing chamber.

The axial cavity 15a in which the needle valve piston 21 slides ends opposite the injection nozzle 16 and comprises a control fluid chamber 24 there as shown.

The control fluid chamber 24 has a slightly larger diameter than the piston 21 and forms an annular shoulder 25 against which rests a larger diameter rear part 26, i.e. the piston head, on which pressure of the control fluid is applied. .

The control fluid chamber 24 has a relatively large length, for example a length equal to 3 to 5 times the control piston stroke, but the stroke of the piston 21 is limited behind by a washer 27 or by other stop members in the chamber 24. Ru.

The dimensions of the chamber 24, in particular its maximum diameter, are such that the thrust exerted at constant pressure by the control fluid is precisely balanced by the counter-thrust exerted on the other end of the piston 21 by the chemical component supplied via the injector, so that the The size is such that it provides a suitable injection pressure.

The control fluid chamber 24 is connected at its rear end, for example by a radial channel 28 and an annular channel 29, to a duct 30, to which a supply line 9 for pressurized fluid is connected.

The remotely controlled injector of the present invention is operated as follows.

Pump 11 constitutes a source of control fluid of constant pressure value for both nozzles 7 and 8 at the same time and can therefore be operated or regulated by remote control without directly influencing mixing head 1.

As a result, the head 24 of each control piston 21 is subjected to a pressure directed towards the injection nozzle, which pressure is maintained in the absence of a counterpressure at the opposite end, i.e. whenever the supply of the chemical components to be mixed is interrupted or Whenever components are circulated separately at fairly low pressure values, piston 2
1 and needle valves 22 and 23 into the nozzle 16
The nozzle is then advanced to the position shown in FIG. 2 where it is closed.

As soon as the component is fed into the injector, i.e. as soon as the counterpressure provided by said chemical component is applied to the end of the piston 21 of the needle valve, this pressure exerts a thrust on the side of the piston 21 opposite the control fluid;
As a result, the piston 21 together with the needle valve is pushed back and rests in a stable equilibrium position in which the nozzle 16 opens and the components are injected into the mixing chamber 2 at the desired pressure value.

During operation, nozzle 1 may be damaged due to an accident, for example, due to impurities.
When the supply pressure of a chemical component changes due to partial blockage of 6, this results in a change in the chemical component pressure to the control cylinder and automatically assumes a different equilibrium position which brings this component supply pressure to the desired supply value. .

This automatic adjustment results from the fact that the control fluid pressure on the head 25 of the piston remains approximately constant.

As is evident from the above description and the accompanying drawings, the present invention enables the operation of each injector by remote control, adjusting each injector to a desired pressure value, and independent of sources that may lead to fluctuations in the component supply pressure. The automatic adjustment ability of the injector is demonstrated.

Although the accompanying drawings illustrate the use of a single control fluid pressure regulator 13 for both injectors, it is clear that individual regulators may be used if desired, and that the nozzle 16 is connected to the mixing chamber plug. When closed by 4, it is also possible to interrupt the supply of control fluid and allow the circulation of the components to take place at a lower pressure or at a pressure considerably lower than the injection pressure, and to circulate the chemical components through the same injector.

The examples described above and shown in the accompanying drawings therefore:
For the mixing head 1 of the reactive chemical components fed into the mold, the needle valve, which determines the injection pressure of the components into the mixing chamber, is no longer an injector of other known types. The idea of the invention is that instead of being balanced by a spring as in , it is simply balanced by the pressure of a control fluid that can be maintained at a nearly constant value during operation of the mixing head, i.e. can be adjusted or varied as required. It will be understood that these are merely examples.

Thus, a precise degree of atomization in the reactive chemical components can be ensured, and better mixing control and better mixture quality can be achieved under any conditions of use.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a typical mixing head with two valves for chemical component injection according to the invention, and FIG. 2 is an enlarged longitudinal sectional view of the injection valve in the mixing head of FIG. DESCRIPTION OF SYMBOLS 1... Mixing head, 2... Mixing chamber, 3... Opening part, 4... Cleaning member, 5... Cylinder, 7, 8...
- Injector, 9, 10... Piping, 11... Pump, 12... Tank, 13... Control fluid pressure adjustment device,
14... Injector body, 15... Cavity, 1
6... Nozzle, 17... Wall part, 18... Annular chamber,
19... component supply duct, 20... radial passage,
21...Piston, 22...Conical part, 23...
- Cylindrical portion, 24... Control fluid chamber, 25... Shoulder, 26... Head, 27... Washer, 28...
... Radial passage, 29 ... Annular path, 30 ... Duct.

Claims (1)

[Scope of Claims] 1. A remotely controlled injector for a mixing head for supplying chemical components into a mold, the mixing head comprising a mixing chamber and having an opening for injecting the components in a part of its side wall; A body having a cylindrical cavity with a nozzle at one end communicating with the pouring aperture of the mixing chamber, said cavity in fluid communication with a supply duct for one component, and a needle valve connected to the cavity of the injector. The needle valve is axially movable within the cavity at the end of the control piston from a closed position to a balanced open position, and the needle valve is axially movable within the cavity at the end of the control piston, and the needle valve is axially movable within the cavity at the end of the control piston. A remotely controlled injector characterized in that it is configured to apply a thrust of a component and a counter thrust of a control fluid having a constant pressure value on the other side. 2. Injector according to claim 1, wherein the injector comprises a control side, which is connected to a source of control fluid via a pressure regulating device. 3. The cavity in which the piston of the needle valve slides extends rearwardly into a control fluid chamber having a length relatively greater than the stroke of the control piston.
Injector described in section. 4 the control fluid chamber has a larger diameter than the control piston;
An injector according to any one of claims 1 to 3, wherein the control piston has a rear head that slides in the control chamber between a front annular shoulder portion in this chamber and a rear stop member. . 5. The control chamber is arranged coaxially outside the control chamber and connected to the fluid supply duct via a radial passage led out from the annular chamber. injector.