Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
FORMER AND METHOD OF MAKING THE SAME
Document Type and Number:
WIPO Patent Application WO/2002/064349
Kind Code:
A1
Abstract:
A process for manufacturing a former (2) for use in the construction of pavement like sites wherein a continuously driven sheet of thermo-plastic (4) is coated with aqueous silicone emulsion (8) and then heated (10) and vacuum formed (14) to the desired shape (16). The heating step serves to remove the aqueous content of the silicone emulsion and an anti-static and anti-adhesive non-detectable micro granular coating results.

Inventors:
HOWDEN ROBERT ELLIS (GB)
Application Number:
PCT/GB2002/000598
Publication Date:
August 22, 2002
Filing Date:
February 11, 2002
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
GRASS CONCRETE LTD (GB)
HOWDEN ROBERT ELLIS (GB)
International Classes:
B29C51/02; B29C51/10; B29C51/16; B29C51/18; B29C69/00; E01C9/00; B29C33/64; B29C51/42; B29C51/44; (IPC1-7): B29C51/10; E01C9/00
Foreign References:
US4331628A1982-05-25
US4944907A1990-07-31
GB2040214A1980-08-28
US4702048A1987-10-27
US3802790A1974-04-09
Attorney, Agent or Firm:
Barnard, Eric Edward (102-108 Clerkenwell Road, London EC1M 5SA, GB)
Download PDF:
Claims:
CLAIMS
1. A process of manufacturing a former (2) for use in the construction of pavement like sites comprising the steps of : i) spraying a continuous belt driven sheet of thermoplastic (4) on at least some of its surface area (6) with an aqueous silicone emulsion (8); ii) heating (10) the sprayed sheet (12) to the optimal temperature ; iii) and vacuum forming (14) of the sheet into a desired former shape (16) comprising at least one shaped hollow body closed at one end.
2. A process of manufacturing a former (2) for use in the construction of pavement like sites comprising the steps of : i) coating at least some surface area (6) of a continuous belt driven drive sheet of thermoplastic (4) with a substance; ii) heating (10) of the thermoplastic sheet (4); iii) and vacuum forming (14) of the sheet into a desired former shape (16) comprising at least one shaped hollow body closed at one end; whereby the coating provides antistatic and antiadhesive qualities to the coated surface.
3. A process according to claim 1 or 2 wherein at least one shaped hollow body is a plurality of shaped hollow bodies.
4. A method for constructing a pavement like site utilising a former manufactured in accordance with claims 1 or 2.
5. A former (2) for use in the construction of pavement like sites comprising: i) at least one shaped hollow body closed at one end and adapted to shape a formable site material; ii) a coating on at least some surface area (6) of the former which provides that surface area with antistatic and antiadhesive properties.
6. A former according to claim 5 wherein the coating comprises of at least micro granular silicone.
Description:
FORMER AND METHOD OF MAKING THE SAME BACKGROUND OF THE INVENTION Field of the Invention The present invention relates in general to formers primarily for use in the construction of pavement-like sites, in particular formers which are void forming moulds for the construction of concrete surfaces. More particularly, the invention relates to a process of making such a former.

Description of the Prior Art A typical state of the art former (20) is shown in Figures I to 3. The former (20) is composed of a plurality of shaped hollow bodies or projections (21) each closed at one end (22). The projections (21) are interconnected by a base sheet (24) and are open at the end adjacent the base sheet (24).

The projections (21) are used to shape a formable site material. Such formers (20) are made from a web of plastic sheet material which is subjected to heating and vacuum forming to assume the shape shown. During construction of a site, one or more formers are placed on the site with the closed ends (22) of the projections (21) uppermost. A formable site material such as concrete (30) is then poured onto the former (20) so as to fill the apertures or gaps between the projections (21) up to or close to the level of the closed ends (22) as shown in Figure 3. When the site material is set the exposed closed ends (22) of the formers (20) are removed, conveniently burned away, to reveal voids extending through to the underlying base. The resultant voids in the site material may then be filled with a further site material, such as soil, which allows grass or other plants to be grown within the voids. It is a disadvantage of the art that during the step of pouring the site material a fine film of the site material may coat the uppermost closed ends (22) of the former. This film then hampers the burning of the closed end of the bodies.

After manufacture the individual formers (20) are placed in a stack and nested together. It is a disadvantage of the art that as a result of the plan and sectional profile (Figures 1 and 2) the formers (20) are susceptible to binding while nested making separation difficult. The problem is compounded by transportation and handling which serves to compress the formers (20) further into the nest. This requires that the formers (20) will be nested with a sufficient gap between their bases, typically 18mm, to allow for subsequent compression, resulting in a reduction in deliverable quantities.

It is thus the aim of the present invention to provide an improved former for use in the construction of pavement like sites.

STATEMENT OF INVENTION According to a first aspect of the present invention there is provided a process for manufacturing a former for use in the construction of pavement like sites comprising the steps of : i) spraying a continuous belt driven sheet of thermo-plastic on at least some of its surface area with an aqueous silicon emulsion; ii) heating the sprayed sheet; iii) and vacuum forming of the sheet into a desired former shape comprising at least one shaped hollow body closed at one end.

According to a further aspect of the present invention there is provided a process for manufacturing a former for use in the construction of pavement like sites comprising the steps of : i) coating at least some surface area of a continuous belt driven drive sheet of thermo-plastic with a substance; ii) heating of the thermo-plastic sheet; iii) and vacuum forming of the sheet into a desired former shape comprising at least one shaped hollow body closed at one end; According to another embodiment of the invention the silicone emulsion can alternatively be applied after the heating stage. The temperature of the plastic must be limited to above 60°C and below 80°C. In this aspect the invention thus provides a process of manufacturing a former which comprises the steps of heating and vacuum forming a sheet of thermo-plastic into a desired former shape with at least one shaped hollow body closed at one end and spraying the former with an emulsion, preferably a silicone emulsion, whilst the shaped former is still at an elevated temperature to create a coating. The coating preferably provides anti-static and anti- adhesive qualities to the coated surface and may be a silicone emulsion.

Further according to the invention there is provided a former for use in the construction of pavement like sites comprising; at least one shaped hollow body closed at one end and adapted to shape a formable site material ; a coating on at least some surface area of the former which provides that surface area with anti-static and anti-adhesive properties. The invention may be understood more readily, and various other features of the invention may become apparent, from consideration of the following description.

BRIEF DESCRIPTION OF DRAWINGS Figure I is a plan view of a typical former; Figure 2 is a section view of the former, the view being taken along the line II-II of Figure 1.

Figure 3 is a view corresponding to Figure 2 and shows the use of the former in creating a site; and Figure 4 is a schematic representation of the process for manufacturing a former in accordance with the invention.

A preferred embodiment of the present invention will now be described by way of example only.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT As represented in Figure 4 a continuously driven sheet or web (4) made, for example, of recycled high impact styrene with a thickness of between (1.14 x 10-3) metres to (1.70 x 10-3) metres is drawn off from a reel (60) and is guided though the various process stages. Initially the sheet (4) is coated on at least one surface (12) with an aqueous silicone emulsion (8). As illustrated, the sheet (4) is coated on both upper and lower surfaces. Emulsion (8) is stored in a header tank (61) and sprayed onto the upper surface (ll). An additional supply of emulsion (8) in a reservoir (65) is dispensed with a sponge wiper (64) to coat the lower surface (12) evenly. Alternatively a pump mechanism can be employed to spray the aqueous silicone emulsion so that it may be stored, remotely. The sheet (4) is guided by a roller (62) and then passed through a heater unit (10) which heats the sheet (4) in preparation for vacuum-forming. The heating step raises the temperature of the sheet (4) to around 150°C. The heating step also causes evaporation of the aqueous content of the silicone emulsion (8) leaving a micro-granular coating of silicone on the previously coated surfaces (11,12) of the sheet. The resultant micro-granular coating gives the coated surfaces (11,12) significant anti-static and anti-adhesive properties without there being a detectable film coating. The sheet is then vacuum formed by tools (14) into the shape previously described in connection with Figures 3 to 5.

The shaped sheet is optionally subjected to a perforation-forming punching operation at a punching station (30) to sub-divide the sheet into pre-determined areas corresponding to individual formers and at a final guillotine station (31) the sheet is severed into individual formers.

A number of variants can be adopted, for example the emulsion (8) can be applied on selected areas of the sheet. It is preferred to apply the emulsion prior to heating but it is possible to locate the coating equipment after the tooling (14). In this case, however, the emulsion (8) is applied to the sheet which is still at an elevated temperature and there is a more restricted range of temperatures at which the emulsion (8) can be successfully applied. Usually the elevated temperature of the sheet should not be outside the range of 60-80°C.

Whichever location is adopted for the coating equipment the formers which are produced overcome the problems discussed hereinbefore. Firstly during use the closed ends (22) of the projections (21) present the coating and inhibit the site material from attaching itself to the closed ends (22). Secondly the coating inhibits the formers from becoming fixed together when stacked.

In this connection the minimum gap of 18mm between the base sheets can be considerably less (10mm or less) and engaging surfaces of the formers do not tend to adhere or lock together.

Typically a nest of formers would occupy a cube of 600mm x 600mm x 1000mm. This same volume can now hold 80% more formers which greatly reduces storage and transport costs.

There is thus provided a plastic former of the type already discussed which has a micro-granular coating of silicone on at least one of its surfaces or part of it's surface area giving significantly anti-static and anti-adhesive qualities to that surface or surface area. The anti-static and anti- adhesive qualities provided by the silicone coating help to prevent binding of the formers when nested together enabling rapid de-nesting of the packed formers ; preventing over-compaction of the formers within the nest and enabling a greater number of formers to be contained within each nest. These properties also help to prevent unwanted adhesion of the filling site material i. e. concrete, to the former preventing a film covering the closed ends of the bodies and hampering of the burning of the closed ends.