GB2123334A - Mould cooling means - Google Patents

Abstract

A cooling circuit of equipment, such as an injection moulding machine (not shown), has cooling passageways to an input end of which one end (4) of a duct (2) is connected and to the output end of which one end (10) of a second duct (9) is connected. Cooling liquid is supplied to the duct (2) at an end (3) thereof, passes through a solenoid shut-off valve (5) and through a manual (6) or automatic (6a) pressure reducing valve, a pressure sensor (7) indicating the pressure. Liquid entering the duct (9) at (10) has its pressure sensed by a pressure sensor and indicator (12) and is drawn in by an electrically driven self-priming liquid ring pump (13). Downstream of the pump are a pressure switch (14), an air/water separator (15) and an automatic air eliminator (16). The pump (13) creates a suction in the duct (9) and in the cooling passageways of the equipment, and the valve (6 or 6a) is adjusted until the sensor (7) shows zero gauge pressure. The passageways thus operate at negative pressure so that air or gas drawn into the passageways can be pumped by the pump (13) with the liquid and be separated out in the separator (15). In the application of use with an injection moulding machine, by using a porous core in a wall of the mould cavity, the negative pressure in the cooling passageways can be used to extract air and other gases from the mould cavity. <IMAGE>

Description

SPECIFICATION Improvements relating to cooling means The invention relates to cooling means and has particular though not exclusive application to the cooling of injection moulding machines for plastics materials.

To keep the cycle time of moulding machines as short as possible, it is desirable to cool the mould.

Generally this is done with water. Particularly where the water passageways in the mould extend across the joint face between two halves of the mould, there is the likelihood that air will get into the cooling water system when the mould is opened and in any event such moulds are prone to sealing problems such that water leakages can occur.

It has been proposed to operate the mould under negative pressure such that in operation any leaks will comprise air leaks into a cooling system rather than water leaks out of the cooling water system but this has previouly involved a by-pass feed to water to a pump which creates the negative pressure in the mould so that the pump will always be primed and will therefore operate effectively.

According to the invention there is provided apparatus for inclusion in a cooling circuit of equipment having cooling passageways, said apparatus comprising first apparatus for connection into the cooling circuit between a source of cooling liquid and said equipment and second apparatus for connection in a return path of cooling liquid from said equipment, said first apparatus comprising adjustable valve means to reduce the pressure in a duct supplying cooling liquid to said equipment substantially to zero pressure gauge and indicating means to indicate the pressure to which the duct is reduced and said second apparatus comprising a self-priming liquid ring pump and indicating means to indicate the suction pressure created by the pump in a duct connecting said pump to said equipment.

Preferably said first apparatus includes a shut-off valve, for example a solenoid valve, and the pressure reducing valve is either manually or automatically operable.

Advantageously, a cooling liquid is water and self-priming liquid ring pump is a CA 60, 80, 90 or 91 or a CAM 60, 80, 90 or 91 pump produced by M S P Planet Ltd., 124 Churchill Road, Launton Road Industrial Estate, Bicester, Oxon The second apparatus can advantageously include an air/water separator and/or an automatic air eliminator such that any air drawn into the waterways in said equipment can be extracted from the water circuit downstream of the pump. If the cooling circuit is fed from a cooling tower and returns water to the cooling tower the air/water separator or automatic air eliminator should no be required, but if the cooling circuit receives water from and return water to a chiller, then the automatic air eliminator or air/water separator will reduce the likelihood of the chillder becoming air-locked by air drawn into the cooling circuit.

Where the equipment is an injection moulding machine for plastics material, by including a porous core, for example of expanded zinc, in a wall of the mould cavity, the reduced pressure in the waterways of the mould can be used to extract air and other gases from the mould cavity, thereby obviating the need momentarily to open the halves of the mould to allow such gases to escape to atmosphere. Thus with such a porous core which is permeable to gases, the air within the mould cavity when the mould is closed and gases collecting therein when plastics material is forced into the mould cavity can be drawn into the cooling water circuit of the mould by the action of the pump and subsequently separated from the cooling water.

The invention is diagrammatically illustrated by way of example in the accompanying drawing, which in an upper part shows a circuit diagram of first apparatus of apparatus according to the invention and in a lower part shows a circuit diagram of second apparatus of apparatus according to the invention.

Referring to the drawing, first apparatus 1 comprises a duct 2 having an inlet end 3 and an outlet end 4 and including a shut-offvalve 5 from a, preferably solenoid operated, shut-off valve and a manual pressure reducing valve 7 or alternatively an automatic reducing valve 6a with a pressure sensing and indicating means 7 connected downstream thereof. The inlet end 3 of the duct 2 is, in use, connected to a pipe through which cooling liquid, usually water, is supplied and the outlet end 4 of the duct is connected to the inlet of equipment which includes cooling passageways, for example the mould of an injection moulding machine.

The second apparatus 8 comprises a duct 9 having an inlet end 10 and an outlet end 11 and including, connected to the duct 9, a pressure sensing and indicating means 12, an electrically driven selfpriming liquid ring pump 13, a pressure switch 15, an air/water separator 15 and an automatic air eliminator 16. The inlet end 10 of the duct 9 can be connected to the outlet of the cooling system of the equipment and the outlet end 11 of the duct can be connected as a return pipe to the source of cooling water to which the inlet end 3 of the duct 2 is connected, for example a chiller or a cooling tower.

In operation, the solenoid valve 5 is operated to open the duct 2 thereby allowing fluid to flow into the apparatus 1. The pressure switch 14 of the apparatus 8 will sense the fluid pressure and will generate a signal to energize the electric motor driving the pump 13. In case air-pockets in the ducts 2 and 9 might allow the pump discharge pressure to fall below the setting of the pressure switch 14, a timer (not shown) is preferably connected across the switch contacts to prevent spasmodic operation.

With the pump 13 running and creating a suction in the duct 9 upstream thereof and thus in the waterways of the equipment (not shown), the valve 6 or the valve 6a is adjuted until the pressure sensing and indicating means 7 indicates a pressure of zero gauge. The waterways within the equipment will thereafter be at negative pressure and thus any air or gases drawn into the waterways will pass through the pump 13 into the air/water separator 15 and out to atmosphere via the eliminator 16. The liquid pumped by the pump 13 will pass to the outlet 11 of the duct 9 and thus back to the source of fluid to be recycled by way of the inlet connection 3 of the duct 2. The pressure sensing and indicating means 12 will indicate the vacuum pressure existing at the inlet of the pump 13.

CLAIMS (Filed 13July1983) 1. Apparatus for inclusion in a cooling circuit of equipment having cooling passageways, said apparatus comprising first apparatus for connection into the cooling circuit between a source of cooling liquid and said equipment and second apparatus for connection in a return path of cooling liquid from said equipment, said first apparatus comprising adjustable valve means to reduce the pressure in a duct supplying cooling liquid to said equipment substantially to zero pressure gauge and indicating means to indicate the pressure to which the duct is reduced and said second apparatus comprising a self-priming liquid ring pump and indicating means to indicate the suction pressure created by the pump in a duct connecting said pump to said equipment.

2. Apparatus according to claim 1, in which said first apparatus includes a shut-off valve and the pressure reducing valve is either manually or automaticaly operable.

3. Apparatus according to claim 1 or claim 2, in which the second apparatus includes an air/water separator and/or an automatic air eliminator such that any air drawn into the waterways in said equipment can be extracted from the water circuit downstream of the pump.

4. Apparatus according to any one of claims 1 to 3, in which the equipment is an injection moulding machine for plastics material and has a mould cavity and a porous core is included in a wall of the mould cavity, whereby the reduced pressure in the waterways of the mould can be used to extract air and other gases from the mould cavity, thereby obviating the need momentarily to open the halves of the mould to allow such gases to escape to atmosphere.

5. Apparatus for inclusion in a cooling circuit of equipment having cooling passages substantially as hereinbefore described and illustrated with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. gases drawn into the waterways will pass through the pump 13 into the air/water separator 15 and out to atmosphere via the eliminator 16. The liquid pumped by the pump 13 will pass to the outlet 11 of the duct 9 and thus back to the source of fluid to be recycled by way of the inlet connection 3 of the duct 2. The pressure sensing and indicating means 12 will indicate the vacuum pressure existing at the inlet of the pump 13. CLAIMS (Filed 13July1983)

1. Apparatus for inclusion in a cooling circuit of equipment having cooling passageways, said apparatus comprising first apparatus for connection into the cooling circuit between a source of cooling liquid and said equipment and second apparatus for connection in a return path of cooling liquid from said equipment, said first apparatus comprising adjustable valve means to reduce the pressure in a duct supplying cooling liquid to said equipment substantially to zero pressure gauge and indicating means to indicate the pressure to which the duct is reduced and said second apparatus comprising a self-priming liquid ring pump and indicating means to indicate the suction pressure created by the pump in a duct connecting said pump to said equipment.

2. Apparatus according to claim 1, in which said first apparatus includes a shut-off valve and the pressure reducing valve is either manually or automaticaly operable.

3. Apparatus according to claim 1 or claim 2, in which the second apparatus includes an air/water separator and/or an automatic air eliminator such that any air drawn into the waterways in said equipment can be extracted from the water circuit downstream of the pump.

4. Apparatus according to any one of claims 1 to 3, in which the equipment is an injection moulding machine for plastics material and has a mould cavity and a porous core is included in a wall of the mould cavity, whereby the reduced pressure in the waterways of the mould can be used to extract air and other gases from the mould cavity, thereby obviating the need momentarily to open the halves of the mould to allow such gases to escape to atmosphere.

5. Apparatus for inclusion in a cooling circuit of equipment having cooling passages substantially as hereinbefore described and illustrated with reference to the accompanying drawings.