GB1599886A

GB1599886A - Grating member and gratings

Info

Publication number: GB1599886A
Application number: GB2960777A
Authority: GB
Original assignee: Laporte Industries Ltd
Current assignee: Evonik LIL Ltd
Priority date: 1977-07-14
Filing date: 1977-07-14
Publication date: 1981-10-07
Also published as: BE868923A; DE2830873A1; DK312078A; NL7807600A; IE781143L; IE46927B1

Description

(54) GRATING MEMBER AND GRATINGS (71) We, LAPORTE INDUSTRIES LIMITED, a British Company, of Hanover House, 14 Hanover Square, London W.1., 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:- The present invention relates to gratings and to grating members.

A significant use of gratings or grating members is to provide a floor for livestock such as pigs or cattle, humans, vehicles or machines such floor being capable of permitting material, which may be liquid, semi-solid or solid but of suitable dimensions, having regard to the spacing of the grating members to pass through the floor. Modern methods of animal husbandry commonly employ pens or other enclosures in which livestock for example pigs or cattle, may be housed at a high density and for prolonged periods the floors of the pens or enclosures comprising gratings, the grating members having a spacing which allows the animals to stand on the floor without significant danger of injury caused, for example, by their feet passing through the grating, while allowing the animal waste products to pass through the grating into a collection facility, e.g. a pit, whence it may be collected for recycling as a fertiliser or for disposal otherwise.

The present invention relates to a floor member in the form of a grating comprising an arrangement, defined hereafter, of grating; members, preferably made from a moulded thermoplastic polymer material. The term floor member is intended to indicate a member capable, with others, of forming a supporting floor for livestock such as pigs or cattle, or for humans, vehicles or machines.

In general, we have found that a thermoplastic polymeric material is especially suitable for use with animals (e.g. pigs).

Wood tends to splinter and stain and may undergo biological attack, apart from being almost prohibitively expensive for use of the kind now envisaged. Steel, or other suitable metals such as cast iron, tends to corrode at least partly because of attack by urine.

Concrete is rather porous and tends to retain the waste matter in surface pores besides being so dense that only relatively small grating members may be handled manually. This last feature of concrete may be pertinent on farms since it is common practice to remove the gratings at intervals to allow access to the underlying collection facility.

The floor members or grating members are preferably made from a thermoplastic dough moulded at a pressure below 200 atmospheres in contrast to normal pressures of above 200 atmospheres which may be used in, for example, extrusion moulding processes. We use the term "dough" to mean a mass made physically workable primarily by the application of shear forces to its components. The dough from which the mouldings are made may be produced by the application of shear forces to a mass of particles of thermo-plastic polymer, admixed if desired with a minor quantity, for example up to 20% by weight, of other materials. The energy imparted by the shear forces causes an increase in temperature sufficient to partially melt the particles and form a mouldable dough. If desired heat may also be imparted to the dough although this may be unnecessary if sufficient shear is utilised. Preferably more than 70% consists of material of the polyolefine class such as polyethylene.

The warm dough may be moulded by feeding it under a pressure below 200 atmospheres, as known in the art, into a shaped receptacle, and thereafter the shaped dough is allowed to solidify in or out of the mould. This technique has been found to result in a moulding having a relatively dense outer portion and a relatively low density core portion.

In practice the core of the mouldings comprises a plurality of small cavities or bubbles. We believe that the resulting characteristic density profile of the mouldings contributes to a relatively high strength/weight ratio. The low density core portion may comprise a roughly central axial portion of the mouldings occupying from about - to 2 of the smallest crosssection of the moulding and comprises a plurality of cavities, having diameters in about the T mm to 3 mm range or even larger, which are formed during solidification of the dough. Preferably the grating members made from thermoplastic from dough derived from mixed thermoplastic waste from the moulding industry since this may result in an extremely cost-competitive product as well as providing waste-recycling. Gratings or grating members made from thermoplastic materials are smooth-surfaced - and are, generally, readily cleaned and sterilised.

Thermoplastic materials have also the general advantage that they can be readily moulded into desired shapes at much lower temperatures than metals. The colour of recycled thermoplastic waste material is usually dark and somewhat unattractive but for gratings in animal sheds this has little or no significance. Plastics generally have lower thermal conductivity than metals and concrete, and are therefore more comfortable for the animals which may thrive better as a result.

The present invention provides a floor member in the form of a grating comprising an arrangement in a horizontal plane or a plurality of substantially T-shaped grating members each having an elongated shaft corresponding to the upstroke of a T and a relatively shorter head corresponding to the cross of the T, in which arrangement (a) the adjacent grating members lie in a "head-to-tail" arrangement, as hereafter defined, with their shafts lying parallel and their heads lying in the plane of the shafts, (b) the shafts of adjacent grating members are spaced by engagement between the head of a member with the shafts of the adjacent members, thereby to define grating slits between the sides of the shafts; (c) the shafts have constant cross section along their lengths: (d) the upper surfaces of the shafts form a planar surface interupted by the slits; and (e) the shafts have cross-sections arranged to define grating slits having downwardly increasing widths. By a "headto-tail" arrangement is meant an arrangement in which the grating members lie with their heads, alternately at opposite sides of the grating.

The present invention further provides a kit of grating members suitable for arrangement into a grating as last above provided.

The present invention further provides a construction for housing animals the floor of which is formed by a grating according to the present invention.

The engagement of adiacent heads and shafts of the grating members makes for stability of the grating members to rocking motion. Because the shafts are of constant cross-section, engagement between a head and a shaft is unaffected if all the shafts are shortened, e.g. by sawing. Therefore, grating members can be supplied to a customer who saws them down to the length dictated by, for example, the existing equipment in his piggery. Alternatively, the mould can be stopped when shorter shafts are desired. Neither of these expedients could be adopted if, for example, each grating member were I-shaped.

It will be noted that two of the overall dimensions of the grating are variable, the one dimension by shortening the shafts of the members and the other dimension by adding or removing members to or from the grating.

Preferably, the shafts of the grating members have a symmetrical cross-section of a shape suitable to provide grating slits of downwardly increasing widths. The present invention provides a floor member having a high solid floor area while providing a passage of solid or semi-solid matter through the floor which is less likely to block than a slit of constant width.

The dimensions of the grating members may be selected with a view to the intended purpose, for example with respect to the dimensions, including weight of vehicles, people, machines or animals which are to rest or move on the grating and with respect to the particular character of the material which is to pass through the slits therein.

The grating arrangement according to the invention may be strengthened by - the inclusion of additional reinforcing spacing members between the shafts to reduce flexure in a horizontal plane which could result in an animal's foot being trapped between adjacent shafts. The spacing members may be moulded integrally with the grating members or may be separately manufactured to a suitable shape to correspond to the conformation of the sides of the slits formed by adjacent grating members. Preferably the sides of the spacing members facing along the slit opening, in position in the grating, are angled towards each other in a downwards direction at an angle to the vertical corresponding to the angle from the vertical of the sides of the shafts.

Preferably tying means, e.g. one or more bars or wires running across the shafts are used in conjunction with the spacing members, to increase the rigidity of the grating member and to spread any load more evenly between the shafts. The insertion of the tie bars or wires is a simple operation since the shafts may be drilled easily to receive them. Preferable a plurality of separate tie bars or wires is used to form separate removable grating sections.

Suitably, adjacent grating members may be connected to each other at their points of engagement after manufacture, e.g. during installation, to increase stability by, for example, the application of heat to the surface areas of the T-arms and the shafts which are to be in engagement so as to produce a weld. A suitable means of applying heat is a hot-air welding torch.

Alternatively the members may be connected by solvent welding. So that the grating may be removed in unitary portions if desired. It is preferred to leave an adjacent pair of members unwelded at suitable intervals.

Unitary portions of a floor member comprising grating sections of the kind above envisaged may also be formed in the course of manufacture, e.g. during the initial moulding operation in which case the T-members of the gratings are only notionally present not having been separately formed. Nevertheless the grating sections so produced provide a new and useful manufacture and constitute a further aspect of this invention. Reference to a number of grating members, in connection with integrally moulded floor sections is to the number of shaft portions said section corresponds to. Integrally moulded grating sections as last described may include one or more spacing members at each end of the section, if required together with, if desired, further reinforcing spacing members and tying means. Such spacing members as are redundant at each end of a run of grating sections may be removed by sawing.

Due to the relatively low density of thermoplastic polymer grating sections moulded at pressures below 200 atmospheres such sections may suitably include from 2 to 6 grating members or their equivalent without being unduly heavy for manual removal and replacement.

Advantageously grating sections-may be moulded as pairs connected at the heads of the grating members with the shafts of the grating members extending outwardly.

Preferably such mouldings include an extra portion of material lying between the joined heads to allow for the precise length of the grating members, including heads, to be selected by cutting away an appropriate portion of the extra material when separating the grating sections.

The grating members whether in integrally moulded grating sections, or not, may be formed with one or more internal reinforcing members, suitably metallic in character, and, suitably, in the form of girders, rods, tubes or bars positioned according to known principles. By this means the members may be brought up to any required minimum strength for use in relation to large loads.

The grating is suitably supported at the ends of the grating members, above the collection facility provided beneath the grating to carry off material which has passed through the slits.

One use, which is preferred, for the grating is in the housing of animals, especially pigs and calves. For this purpose a suitable arrangement consists of a pit or trough with a rim having a horizontal flange and a vertical lip. The grating members in appropriate relative position lie across the width of the trough supported on the flange at either side, and are prevented from slipping lengthwise out of the proper arrangement by the lip. The floor of the trough may slope downwards to permit the animal waste material to run away. Suitable pits or troughs of this type are already known in the art.

It may be desirable to adjust the dimensions of the grating members if animals other than pigs are involved. Cattle are bigger, and therefore the grating member will in general be longer. Because of the increased length of the member and also the generally greater weight of calves, it may be desirable to reinforce the grating member as above described.

The present invention will now be more particularly described with reference to figures 1 to 7 accompanying the Provisional Specification which illustrate embodiments of the invention suitable for use in the housing of pigs.

Figure 1 shows an assembled grating in plan view, schematically, only the axes of the shafts (1) and heads (2) of the members being shown.

Figure 2 shows two adjacent members of the grating, shown in Figure 1, in an exploded perspective view.

Figure 3 shows an end view of one of the members shown in Figure 2 in the direction of arrow A.

Figure 4 shows the section of the grating (not exploded) along the line B-B of Figure 1 or Figure 2.

Figure 5 shows a section through a grating in accordance with the present invention, in the same sense as Figure 4 but showing a variation in the cross-sectional shape of the grating members.

Figure 6 shows a section through a shaft of another grating member in accordance with the present invention.

Figure 7 shows, schematically, possible variations of the conformation of the grating members from the strict T-shape shown in Figures 1o.

The dimensions of the grating member shown in Figure 2 are:- (a) length including head-1088 mm (b) width of shaft across upper surface 79 mm (c) thickness of head vertical to upper surface-67 mm (d) length of head along upper surface at right angles to shaft-126 mm All dimensions can be varied to a greater or lesser extent. It is to be understood that the dimensions given are, strictly, those of the internal wall of the mould used to make the grating member, and that a shrinkage of up to 2% on any linear dimension has been allowed for in the designing of the mould. In the assembled grating, surfaces 5 and 6 of grating member 4 (being the end faces of the head) engage corresponding side surfaces (not visible in the Figure) of the shaft of member 3. The engagement consists in contact or near contact between the surfaces. A similar engagement occurs between the side surfaces 7 and 8 of the shaft of the member 4 and the end surfaces (not visible in the Figure) of the head 9thereof.

The cross-section of the shaft is (see Figure 3) approximately that of a trapezium in outline, the four sides of the outline being marked 10, 11, 12 and 13. Side 10 is the bearing surface of the shaft which, together with the surfaces of the other shafts, forms a planar surface interrupted by slits.

Chamfers 14 and radii 15 are optional.

Chamfers 14 render the corners of the bar less likely to be broken off than if the corners were unchamfered.

The slits are defined by the engagement between the heads and shafts. This is shown in more detail in Figure 4, in which the walls of a slit are marked 16. It will be observed that the slits have downwardly increasing width.

In the embodiment shown in Figures 1 to 4 the floor surface formed consists of solid planar surfaces of width 79 mm and slits of width 23.5 mm. The slits are vertical for 10 mm below the floor surface, and then widen downwards, the sides being at an angle of about 12C to the vertical. We find these dimensions to be a good compromise for the housing of pigs it being borne in mind that a shed may contain both a sow and piglets.

The embodiment of the invention shown in Figures 1 to 4 contains moulded grating members comprising recycled thermoplastic waste of which about 80% is comprised of polyolefin polymers.

In Figure 5 the outline of the shaft section 17 is approximately that of a trapezium, but two of the angles of the trapezium are right angles. Nevertheless the slits of the grating (with sides 18) widen downwardly. Also, the heads and shafts engage in contact or near contact over a substantial area, as in the case of the grating previously described.

However, alternate members are mirror images of one another, and this may be inconvenient in production and assembly.

For this reason we, in general, prefer shafts which are symmetrical about a plane perpendicular to the surface which forms the upper surface of the grating. In that case, all members of a kit of grating members can be identical.

Another shaft cross-section which would also be suitable is shown in Figure 6.

There is a possibility of variation from the strict T-shape shown in Figures 1 to 4. The head of the grating member may in fact comprise two arms, one to each side of the shaft, either or both of which are not at the end of the shaft. Further or alternatively, the head of the grating member need not be perpendicular to the shaft. This will generally be less convenient than a true Tshape, but the property of adjustable grating member length (discussed above, and not shared by, for example, an I-shaped member) is retained. Variations as last above described are illustrated in Figure 7.

WHAT WE CLAIM IS: 1. A floor member in the form of a grating comprising an arrangement in a horizontal plane of a plurality of substantially Tshaped grating members each having an elongated shaft corresponding to the upstroke of a T and a relatively shorter head corresponding to the cross of the T, in which arrangement (a) the adjacent grating members lie in a "head-to-tail" arrangement, as hereinbefore defined, with their shafts lying parallel and their heads lying in the plane of the shafts, (b) the shafts of adjacent grating members are spaced by engagement between the head of a member and shafts of the adjacent members, thereby to define grating slits between the sides of the shafts; (c) the shafts have constant cross section along their lengths; (d) (d) the upper surfaces of the shafts form a planar surface interrupted by the slits; (e) the shafts have cross-sections arranged to define grating slits having downwardly increasing widths.

2. A floor member as claimed in claim 1 wherein the shafts of the grating members have a symmetrical cross-section.

3. A floor member as claimed in claim 1 or 2 having additional spacing members between the shafts of the grating members.

4. A floor member as claimed in claim 3 having tie bars or wires running across the

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

Claims

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

The dimensions of the grating member shown in Figure 2 are:- (a) length including head-1088 mm (b) width of shaft across upper surface 79 mm (c) thickness of head vertical to upper surface-67 mm (d) length of head along upper surface at right angles to shaft-126 mm All dimensions can be varied to a greater or lesser extent. It is to be understood that the dimensions given are, strictly, those of the internal wall of the mould used to make the grating member, and that a shrinkage of up to 2% on any linear dimension has been allowed for in the designing of the mould. In the assembled grating, surfaces 5 and 6 of grating member 4 (being the end faces of the head) engage corresponding side surfaces (not visible in the Figure) of the shaft of member 3. The engagement consists in contact or near contact between the surfaces. A similar engagement occurs between the side surfaces 7 and 8 of the shaft of the member 4 and the end surfaces (not visible in the Figure) of the head 9thereof.

The cross-section of the shaft is (see Figure 3) approximately that of a trapezium in outline, the four sides of the outline being marked 10, 11, 12 and 13. Side 10 is the bearing surface of the shaft which, together with the surfaces of the other shafts, forms a planar surface interrupted by slits.

Chamfers 14 and radii 15 are optional.

Chamfers 14 render the corners of the bar less likely to be broken off than if the corners were unchamfered.

The slits are defined by the engagement between the heads and shafts. This is shown in more detail in Figure 4, in which the walls of a slit are marked 16. It will be observed that the slits have downwardly increasing width.

In the embodiment shown in Figures 1 to

4 the floor surface formed consists of solid planar surfaces of width 79 mm and slits of width 23.5 mm. The slits are vertical for 10 mm below the floor surface, and then widen downwards, the sides being at an angle of about 12C to the vertical. We find these dimensions to be a good compromise for the housing of pigs it being borne in mind that a shed may contain both a sow and piglets.

The embodiment of the invention shown in Figures 1 to 4 contains moulded grating members comprising recycled thermoplastic waste of which about 80% is comprised of polyolefin polymers.

In Figure 5 the outline of the shaft section

17 is approximately that of a trapezium, but two of the angles of the trapezium are right angles. Nevertheless the slits of the grating (with sides 18) widen downwardly. Also, the heads and shafts engage in contact or near contact over a substantial area, as in the case of the grating previously described.

However, alternate members are mirror images of one another, and this may be inconvenient in production and assembly.

For this reason we, in general, prefer shafts which are symmetrical about a plane perpendicular to the surface which forms the upper surface of the grating. In that case, all members of a kit of grating members can be identical.

Another shaft cross-section which would also be suitable is shown in Figure 6.

There is a possibility of variation from the strict T-shape shown in Figures 1 to 4. The head of the grating member may in fact comprise two arms, one to each side of the shaft, either or both of which are not at the end of the shaft. Further or alternatively, the head of the grating member need not be perpendicular to the shaft. This will generally be less convenient than a true Tshape, but the property of adjustable grating member length (discussed above, and not shared by, for example, an I-shaped member) is retained. Variations as last above described are illustrated in Figure 7.

WHAT WE CLAIM IS: 1. A floor member in the form of a grating comprising an arrangement in a horizontal plane of a plurality of substantially Tshaped grating members each having an elongated shaft corresponding to the upstroke of a T and a relatively shorter head corresponding to the cross of the T, in which arrangement (a) the adjacent grating members lie in a "head-to-tail" arrangement, as hereinbefore defined, with their shafts lying parallel and their heads lying in the plane of the shafts, (b) the shafts of adjacent grating members are spaced by engagement between the head of a member and shafts of the adjacent members, thereby to define grating slits between the sides of the shafts; (c) the shafts have constant cross section along their lengths; (d) (d) the upper surfaces of the shafts form a planar surface interrupted by the slits; (e) the shafts have cross-sections arranged to define grating slits having downwardly increasing widths.
2. A floor member as claimed in claim 1 wherein the shafts of the grating members have a symmetrical cross-section.
3. A floor member as claimed in claim 1 or 2 having additional spacing members between the shafts of the grating members.
4. A floor member as claimed in claim 3 having tie bars or wires running across the

shafts of the grating members to hold them together.
5. A floor member as claimed in any one of claims I to 4 wherein adjacent grating members are connected at their points of engagement.
6. A floor member as claimed in claim 5 wherein said connection is performed after manufacture of the grating members.
7. A floor member as claimed in any one of claims 1 to 6 in the form of an arrangement of thermoplastic polymer mouldings.
8. A floor member as claimed in claim 7 wherein the mouldings are formed at a pressure below 200 atmospheres.
9. A floor member as claimed in claim 7 or 8 wherein the thermoplastic polymer comprises more than 70% by weight of a material of the polyolefin class.
10. A section of a floor member as claimed in any one of claims 1 to 9 in the form of a grating section comprising a plurality of grating members connected to each other or held together.
11. A floor member as claimed in any preceding claim including one or more metallic reinforcing members.
12. A floor member as claimed in claim 5 in the form of an integrally moulded thermoplastic polymer grating section including from 2 to 6 grating members.
13. A kit of grating members suitable for arrangement to form a floor member as claimed in any one of claims 1 to 11.
14. A floor member as claimed in claim 1 and substantially as described herein with reference to and as illustrated by Figures 1 to 4 of the drawings.
15. A floor member as claimed in claim 1 and substantially as described herein with reference to and illustrated by any one of Figures 5 to 7 of the drawings.
16. An enclosure for livestock including a floor member as claimed in any preceding claim and an underlying livestock waste' product collection facility.