GB1604987A

GB1604987A - Method and apparatus for the manufacture of filter elements

Info

Publication number: GB1604987A
Application number: GB2488578A
Authority: GB
Original assignee: PLASTIC ENGS Ltd
Current assignee: PLASTIC ENGS Ltd
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-12-16

Description

(54) A METHOD AND APPARATUS FOR THE MANUFACTURE OF FILTER ELEMENTS (71) We, PLASTIC ENGINEERS LIMITED, a British Company of Treforest Industrial Estate, Near Pontypridd, Glamorgan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a method and apparatus for the manufacture of disc type filter elements.

In the manufacture of all plastics strainer type filters by injection moulding, current practice is to load the mesh preform into a mould by hand. For cylindrical shaped filters, cylindrical shaped preforms are loaded on to the cores of a mould by hand before the mould halves are closed for injection. For flat disc type filters, and for cylindrical filters closed at one end with a mesh disc, the disc preform is loaded in one of the following ways. In a vertical machine the disc is simply laid flat on the horizontal mould surface in the appropriate position. In a horizontal machine the disc is temporarily attached to the vertical face of the core or cavity, by means of a double sided adhesive panel, by wetting, by liquid adhesive, or by locating on a core pin if the filter is designed with a central hole in its base.

The manual insertion of this filter preform can occupy a disproportionately large percentage of the total moulding cycle and thus reduce the potential output rate of the moulding machine and increase production costs.

The purpose of this invention is to use an automatic method to produce filter elements for disc filters or for the closed end of cylindrical filters and thereby to increase output rates.

According to this invention therefore we provide a method of manufacturing disc filter elements by intermittently feeding into a mould a strip of mesh material moving a core to punch out of said strip when stationary a disc of mesh material and feed it into the mould cavity to hold it there. moving an auxiliary core into the mould cavity to punch a hole in said disc, injecting plastics material around the periphery of said hole and around the periphery of said disc to form a frame to support said mesh, and then withdrawing said core to free the filter element so formed from the cavity.

There is also provided apparatus for manufacturing disc filter elements comprising a mould having a cavity therein of a shape corresponding to the shape of the element to be moulded, means for intermittently feeding a strip of mesh material into the mould, a first core, means for moving said first core when said strip is stationary to punch out a disc of mesh material from said strip and feed it into the cavity and hold it there, a second core, means for moving said second core to punch a hole in said disc and means for injecting plastics material around the periphery of said hole and around the periphery of said disc to form a frame to support said mesh.

In a preferred embodiment of the invention to be described in detail hereinafter, filter mesh is supplied in the form of a continuous roll wound on a spool. The mesh strip is fed across the open face of a mould in the correct location relative to the mould cavity. As the mould closes the core punches out a disc from the strip of the correct size and shape and pushes this into the base of the cavities i.e. in the correct position for moulding.

The surplus strip from which the disc had been punched out is wound up in a roll on a spool on the opposite side of the mould.

The intermittent movement of the strip across the mould and the winding action of the spools is actuated by the opening and closing action of the mould in a similar way to the action of a punch press fabricating parts from metal strip.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which: FIGURE 1 is a cross-section through a mould in accordance with this invention in a closed position for producing filter elements; FIGURE 2 shows the mould of Figure 1 in the open position; and FIGURE 3 shows a filter element pro duced by the mould shown in Figures I and 2.

The mould I shown in Figures I and 2 comprises three main sections 2. 3 and 4.

Section 2 comprises an injection nozzle 5 clamped to an injection cavity-forming block 6 by means of a plate 7. The injection cavityforming block 6 is shaped to provide channels to form the solid parts 8 to the disc filter element 9 to be formed and has an exit hole 10 for scrap punched out of a strip of plastics filter mesh material 11 which is fed through a passageway 12 in section 3 from a feed spool 13 to a take up spool 14 across the opening to the cavity formed by a bore 15 in block 16 of section 3. The bore 15 receives a main core 17 mounted on a further block 18 forming part of section 4, another block 19 mounts auxiliary cores 20 and 21 which together can be moved relative to the main core 17.

As is seen in Figure 1, the injection nozzle orifice 22 is located at a position in the cavity-forming block 16 to inject molten plastics material around the periphery of a disc of mesh material 23 held in the base of the cavity by the main core 17.

In operation the strip of mesh material is fed into the passageway 12 onto take-up spool 14 and is held taunt. Blocs 18 and 19 are then moved by means not shown into the bore 15 wherein the main core 17 shears a circle of mesh 23 from the strip 11 and carries it down to the bottom of the cavity holding it there when the auxiliary cores 20 and 21 are then moved relative to the main core 17 to punch out holes 24 and 25 shown in Figure 3, the mesh material punched out being ejected from the exit hole 10. Molten plastics material, preferably nylon is injected into the nozzle 5 and exits from the orifice 22 to pass into the channels which form the solid parts 8 of the element 9. The end 26 of the main core 17 may have channels located in the same position as in the injection cavity-forming block 6 so that the solid parts 8 extend on each side of the filter mesh disc 23 after injection moulding.

After moulding the sections 3 and 4 are moved away from the section 2 allowing a completed moulded filter element to be ejected. The section 4 then continues its movement back away from section 3 so that the main core 17 and auxiliary cores 20 and 21 clear the passageway 12 in section 3. The filter mesh material strip 11 is then advanced by a distance slightly greater than the diameter of the bore 15 and then held stationary so that another moulding operation may commence when section 3 is moved up to section 2 before section 4 is advanced to enable the main core 17 to shear a disc of mesh material from the strip 11.

The movement of the sections and the intermittent advance of the strip mesh material are synchronized so that the operation is entirely automatic and continuous.

The filter element need not be circular, it could be hexagonal or any other shape. The outer circumfcrential shape is dictated by the shape of the cavity in the block 6 whilst the shape of the filter mesh is dictated by the shape of the bore 15. Thus the outer solid parts of a filter element may be in the form of a hexagon whilst the mesh filter area moulded into the solid circumference may be circular. The cavity may be shaped to provide strengthening ribs for the element.

The mesh is preferably of nylon but may be of other plastics material, or it may be of metal.

To obtain an effective shearing action the plane of the mesh material across the bore 15 is at an acute angle to the direction of movement of the core 17.

It will be appreciated that by suitable provision of channels in the cavity forming block 6 any configuration of filter may be moulded having solid areas and areas of mesh at locations dictated by the use of that element.

WHAT WE CLAIM IS: 1. A method of manufacturing disc filter elements by intermittently feeding into a mould a strip of mesh material, moving a core to punch out of said strip when stationary a disc of mesh material and feed it into the mould cavity to hold it there, moving an auxiliary core into the mould cavity to punch a hole in said disc, injecting plastics material around the periphery of said hole and around the periphery of said disc to form a frame to support said mesh, and then withdrawing said core to free the filter element so formed from the cavity.

2. A method as claimed in Claim 1, wherein said mesh material is plastics material and the movement of said strip across said cavity is synchronized with the operation of said core or cores.

3. A method of manufacturing disc filter elements substantially as described herein with reference to the accompanying drawings.

4. Apparatus for manufacturing disc filter elements comprising a mould having a cavity therein of a shape corresponding to the shape of the element to be moulded, means for intermittently feeding a strip of mesh material into the mould, a first core, means for moving said first core when said strip is stationary to punch out a disc of mesh material from said strip and feed it into the cavity and hold it there, a second core, means for moving said second core to punch a hole in said disc and means for injecting plastics material around the periphery of said hole and around the periphery of said disc to form a frame to support said mesh.

5. Apparatus as claimed in Claim 4

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. duced by the mould shown in Figures I and 2. The mould I shown in Figures I and 2 comprises three main sections 2. 3 and 4. Section 2 comprises an injection nozzle 5 clamped to an injection cavity-forming block 6 by means of a plate 7. The injection cavityforming block 6 is shaped to provide channels to form the solid parts 8 to the disc filter element 9 to be formed and has an exit hole 10 for scrap punched out of a strip of plastics filter mesh material 11 which is fed through a passageway 12 in section 3 from a feed spool 13 to a take up spool 14 across the opening to the cavity formed by a bore 15 in block 16 of section 3. The bore 15 receives a main core 17 mounted on a further block 18 forming part of section 4, another block 19 mounts auxiliary cores 20 and 21 which together can be moved relative to the main core 17. As is seen in Figure 1, the injection nozzle orifice 22 is located at a position in the cavity-forming block 16 to inject molten plastics material around the periphery of a disc of mesh material 23 held in the base of the cavity by the main core 17. In operation the strip of mesh material is fed into the passageway 12 onto take-up spool 14 and is held taunt. Blocs 18 and 19 are then moved by means not shown into the bore 15 wherein the main core 17 shears a circle of mesh 23 from the strip 11 and carries it down to the bottom of the cavity holding it there when the auxiliary cores 20 and 21 are then moved relative to the main core 17 to punch out holes 24 and 25 shown in Figure 3, the mesh material punched out being ejected from the exit hole 10. Molten plastics material, preferably nylon is injected into the nozzle 5 and exits from the orifice 22 to pass into the channels which form the solid parts 8 of the element 9. The end 26 of the main core 17 may have channels located in the same position as in the injection cavity-forming block 6 so that the solid parts 8 extend on each side of the filter mesh disc 23 after injection moulding. After moulding the sections 3 and 4 are moved away from the section 2 allowing a completed moulded filter element to be ejected. The section 4 then continues its movement back away from section 3 so that the main core 17 and auxiliary cores 20 and 21 clear the passageway 12 in section 3. The filter mesh material strip 11 is then advanced by a distance slightly greater than the diameter of the bore 15 and then held stationary so that another moulding operation may commence when section 3 is moved up to section 2 before section 4 is advanced to enable the main core 17 to shear a disc of mesh material from the strip 11. The movement of the sections and the intermittent advance of the strip mesh material are synchronized so that the operation is entirely automatic and continuous. The filter element need not be circular, it could be hexagonal or any other shape. The outer circumfcrential shape is dictated by the shape of the cavity in the block 6 whilst the shape of the filter mesh is dictated by the shape of the bore 15. Thus the outer solid parts of a filter element may be in the form of a hexagon whilst the mesh filter area moulded into the solid circumference may be circular. The cavity may be shaped to provide strengthening ribs for the element. The mesh is preferably of nylon but may be of other plastics material, or it may be of metal. To obtain an effective shearing action the plane of the mesh material across the bore 15 is at an acute angle to the direction of movement of the core 17. It will be appreciated that by suitable provision of channels in the cavity forming block 6 any configuration of filter may be moulded having solid areas and areas of mesh at locations dictated by the use of that element. WHAT WE CLAIM IS:

1. A method of manufacturing disc filter elements by intermittently feeding into a mould a strip of mesh material, moving a core to punch out of said strip when stationary a disc of mesh material and feed it into the mould cavity to hold it there, moving an auxiliary core into the mould cavity to punch a hole in said disc, injecting plastics material around the periphery of said hole and around the periphery of said disc to form a frame to support said mesh, and then withdrawing said core to free the filter element so formed from the cavity.

5. Apparatus as claimed in Claim 4

wherein said mould comprises a block having a passageway therethrough across the opening to said cavity through which said mesh material is fed, the passageway across said cavity being at an acute angle to the direction of movement of said core.

6. Apparatus as claimed in Claim 4 or 5, wherein said cavity is shaped to provide strengthening ribs to said element as the plastics material is injected into the cavity.

7. Apparatus for manufacturing filter elements substantially as described with reference to the accompanying drawings.

8. A filter element when made by the method claimed in any one of Claims 1 to 4.

9. A filter element produced by the apparatus as claimed in any one of Claims 4 to 7.