GB2189426A - Forming an article of ceramics material - Google Patents

Abstract

The method comprises the steps of forming a main body member of the article of ceramics material; surrounding the member with an outer shell. The exemplified product is a lamp base (1) comprising a main body member (2) cast of potters fine casting clay surrounded by a thin shell (4) of PVC material having side walls (5) extending between end caps (6) and (7). A bore (12) formed in the body member (2) during casting accommodates a cable to a bulb holder (14). To form the lamp base the main body member is cast and dried at room temperature. The outer shell is formed and slid and bonded onto the main body member. A hole (17) is drilled into the bore and the fittings, including the cable are then mounted on the lamp base. Alternatively, the main body member may be cast within the outer shell. <IMAGE>

Description

SPECIFICATION A method for forming an article The present invention relates to a method for forming an article, and in particular, though not limited to a method forforming a lamp base, such as, for example, a lamp base for a table lamp orthe like.

The invention also relates to the article and/or lamp base.

In many cases, it is desirabletoformalamp base or indeed any other article from a ceramics material.

The normal processforforming a lamp base orother such article from a ceramics materials isthatthe article is first moulded from the ceramics material which may be any suitable casting clay, such as, for example, potters fine casting plaster, or the like in a mould. On setting, the moulded article is removed from the mould and placed in a kilnforfiring and drying. This process can take a number of hours, in most cases. The article is then glazed, or should it be desired to provide a coloured article, the article would normally be painted first, and then glazed.

However, after glazing, it is essential to place the article in a kiln again forfurtherfiring, drying and baking ofthe glazed material. This, it will be appreciated, has many disadvantages. First of all, considerable costs are involved in kiln-drying the moulded article in the first instance, and then baking on the glaze thereafter. Furthermore, the capital cost of insulation of suitable kiln equipment can be relatively expensive. Afurther problem with casting articles and indeed lamp bases is that unless one is particularly careful when removing the mould, very often portions of the moulded article may break off during mould removal. This, in general, leads to the scrapping of the article.

There is therefore a need for a method forforming an article, and/or a lamp base of ceramics material, which avoids problems of methods known heretofore. There is also a need for an article and lamp base made according to the method.

The present invention is directed towards providing such a method and article.

According to the invention, there is provided a method for forming an article of ceramics material comprising the steps offorming a main body member of the article of ceramics material and surrounding the main body memberwith an outer shell. Preferably, the main body member is moulded in a mould and allowed to set in the mould.

Advantageously, the main body member is removed from the mould and allowed to dry at room temperature. In one embodiment of the invention, the main body member is an elongated body member and a bore extending longitudinally through the main body member is formed during moulding.

Further,the invention provides a method for forming an articlewhich includesthe steps of forming the outer shell ofthe article, forming the main body member in the outer shell by moulding the ceramic material in the outer shell, and allowing the ceramic material to set in the outer shell.

Preferably, the method includes the step of forming the outer shell with an open mouth, and advantageously, the method includes the step of placing the outer shell in a support mould with the open mouth directed upwardly, and pouring the ceramic material mixed with water into the outer shell through the open mouth. Advantageously, an end cap is secured to the outer shell to close the open mouth.

Additionally, the invention provides a method for forming a lamp base, the method comprising the following stepsforming a main body member of ceramicsmaterial,forming partofanoutershell in the form of a sleeve like member, and sliding and securing the sleeve-like member onto the main body member. Preferably,themain bodymemberis provided by an elongated body member, and a bore is cast longitudinallytherethrough. Advantageously, a pair of end caps are secured to the ends ofthe main body member and to the ends ofthe sleeve-like member.

Further,the invention provides an article formed according to the method of the invention, the article comprising an outer shell surrounding a main body memberformed of ceramics material.

In oneembodimentoftheinvention,thearticleisa lamp base, and comprises an elongated main body member with a bore to accommodate a cable extending longitudinallytherethrough.

Advantageously, the outer shell is of sheet material, preferably of PVC sheet material.

The invention will be more clearly understood from the following description of some preferred embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which: Figure lisa perspective view of a lamp base according to the invention.

Figure2 is a sectional perspective view of the lamp base of Figure 1, Figure 3 is a plan view of portion ofthe lamp base of Figure 1 developed, Figure 4 is an exploded view of portion ofthe lamp base of Figure 1, Figure 5 is a perspective view of portion of the lamp base of Figure 1 being assembled, Figure 6 is a perspective view of portion of the lamp base of Figure 1 further being assembled, Figure 7 is a perspective view of portion of a mould for moulding part ofthe lamp base of Figure 1, Figure 8 is a perspective view of a lamp base according to another embodiment ofthe invention, Figure 9 is a perspective view of a lamp base according to a still further embodiment of the invention, Figure 10 is a perspectiveview of portion ofthe lamp base of Figure 9, Figure 11 is a perspective view of a mould for use in the lamp base of Figure 9, Figure 12 is a sectional perspectiveviewofthe lamp base of Figure 9 in a further stage of construction, and Figure 13 is a sectional perspective view ofthe lamp base of Figure 9.

Referring to the drawings and initially to Figures 1 to 7 there is illustrated a lamp base according to the invention, indicated generally by the reference numeral 1 formed by a method also according to the invention.The method forforming the lamp base 1 is described below. The lamp base 1 comprises a main body member 2 surrounded by a relativelythin walled outer shell 4 having foursidewalls 5of concave shape, which terminate in a top end cap 6 and a bottom end cap 7. The side walls 5 are of PVC material andformedfrom a blank8provided bya sheet of PVC material as illustrated in Figure 3 and described below. The end caps 6 and 7 are also of PVC material.The body member 2 is of ceramics material, in this case potters fine casting plaster and is moulded with a bore 12 extending between the end caps 6 and 7to accommodate a cable 13. Abulb holder 14 is secured to the lamp base 1 by a threaded nipple 15 which extends through a portion 32 ofthe bore 12 of reduced diameter and through a hole 16 in the top end cap 6. A spacer 33 is provided on the nipple 15 between the bulb holder 14 and the end cap 16. The nipple 15 engages threads (not shown, on the bulb holder 14 and a nut 35 secures the nipple 15 within the bore 12. A hole 17through the side wall 5 and the main body member 2 accommodates the cable 13 into the bore 12.A grommet 19 is provided on the outer end ofthe hole 17 and a safety grommet 36 is provided on the cable 13 to avoid the cable being pulled through the hole 17.

The lamp base is constructed according to the following method. The body member 2 is cast in a silicone rubber mould. Such mouldswill be well known to those skilled in the art and the mould is not described or illustrated. Prior to casting the body member, a removable plug 29, see Figure 7, is placed centrally in the mould (not shown) to form the central bores 12 and 32. The plug 29 is of timber and has an elongated portion 30 to form the bore 12 and a short portion 31 of reduced cross sectional area to form the bore 32. The portion 30 is tapered very slightly towards the portion 31 for ease of removal of the plug and the portion 31 is also provided with a very slighttaper in the same direction.Potters fine casting plaster is then mixed with water and poured intothe mould and allowed to set. Onceset,the removable plug is removed from the cast body member 2 and the body member 2 is then removed from the rubber mould and allowed to dry at room temperature. As can be seen, the outer surface 3 of the main body member 2 is shaped with concave side walls to form the concave side walls 5 of the outer shell 4. The outer surface ofthe mould is then sealed with size.

The outer shell 4 is formed by cutting outthe blank 8 illustrated in Figure 2toform a sheetof PVC material. Simultaneously with cutting out the blank 8, fold lines 18which areformed by lines of weakness are impressed into the blank8 in a suitable pressing tool. The fold lines 18 are illustrated by broken lines. The blank 8 is then bent along the fold lines 18toform thefourside walls 5 and a securing tab 20. The tab 20 is secured to the edge 21 of the side wall 5 by adhesive, in this case an adhesive sold underthe Trade Mark "SUPERGLUE" to form a sleeve-like member 38, see Figures 4 and 5.The outer surface 3 of the body member 2 is coated with an adhesive, in this case a water based glue sold underthe Trade Mark POLYBOND and the sleeve-like member 38 is slid onto and thus bonded to the bod-y member 2, as illustrated in Figure 5. Thetop end of the body member is coated with POLYBOND and placed upside down on top of a sheet 39 of PVC material as illustrated in Figure 6. A bead 41 of "SUPERGLUE" from a dispenser43 is provided on the PVC sheet 39 around the sleeve-like member 38 to bond the sheet of material 39 to the sleeve-like member 38. The sheet 39 is then trimmed to form the end cap 6. The hole 16 is cut in the end cap 6.

The hole 17 is drilled through one side wall5 through the body member 2 into the bore 12to accommodatetheelectrical cable 13. The cable 13 is threaded through the holes 17 and the grommet 19 is secured at the outer end of the hole 17. The safety grommet 36 is secured on the cable. The portion of the cable within the bore 17 is threaded through the nipple 15 and connected to the bulb holder 14, which in turn is secured to the nipple 15. The bottom end of the cap 7 is formed from a sheet of PVC material similarto the sheet 39 and secured to the bottom end ofthe lamp base in similarfashion as the top end cap 6.

Referring now to Figure 8there is illustrated a lamp base 40 according to another embodiment of the invention. In this case the lamp base 40 is substantially to the lamp base 1 and similar components are identified by the same reference numeral. This lamp base 40 is also constructed using a similar method. The only difference between this lamp base 40 and the lamp base 1 is that two lengths of beading 42 of plastics material are secured to the side walls 5 adjacent the end caps 6 and 7 to conceal the free edges of the end caps 6 and 7.

Referring now to Figures 9 to 13 there is illustrated a lamp base 50 according to another embodiment of the invention. This lamp base is also substantially similartothelampbasel and similar components are identified by the same reference numerals. The main difference between this lamp base and the lamp base 1 is in the method of construction. In this case, the outer shell comprising the sleeve-like member 38 and the top end cap 6 are formed initially and the main body member 2 is cast directly into the outer shell 4. The sleeve-like portion 38 ofthe outer shell 4 isformed from a blanksimilartothe blank8 of Figure 3. The end caps 6 abd 7 are formed buy a vacuum forming process which will be well known to those skilled in the art, and each comprise a base 9 with side walls 10. The top end cap 6 is secured to the sleeve-like member 38 by bonding the side members 10tothesidewalls5with "SUPERGLUE".Thus,the outer shell 4 is formed with an open mouth 24, see Figure 10. The shell is inverted and placed in a support mould 26 with the open mouth 24facing upwardly. The support mould 26 is oftimber material having a hollow interior 27 which defines the outer surface of the shell 4. The plug 29 is placed centrally in the outershell Land illustrated in Figure 12.

Once the top end cap 6 is secured to the side walls 5, the side members 10 of the end cap 6 retain the side walls 5 with a substantially concave shape as illustrated in Figure 5. On insertion into the interior 27 ofthe mould 26, the side walls 5 ofthe outershell 4are supported and the concave shape oftheside walls 5 is retained. Furthermore, the support mould 26 prevents the side walls 5 distorting whilethe main bodymember2is influidform.

The potters fine casting plaster is mixed with water in conventional fashion, and poured into the hollow shell 4,thusfilling the shell to the open mouth 24.

The plaster 11 is allowed to set. The releasable plug 29 is removed and the outer shell 4 with the main body member 2 cast within is removed from the support mould 26.

The hole 17 is drilled through one ofthe side walls 5through the body member 2 into the bore 12. The rest of the assembly of the lamp base 50 is similarto the assembly described with reference to Figures 1 to7.

It has been found that the invention has many advantages over known methodsforforming lamp bases or indeed any other articlefrom a mouldable ceramics material. A particular advantage isthat it leads to a relatively easily manufactured article which can be produced at a relatively low cost. In particular, it has the great advantage that complex shapes may be cast without any ofthe difficulties of casting such shapes using known methods of casting. For example, one particular problem with forming articles of complex shape from casting is the difficulty in removing the moulded article from the mould after the article has been cast without damage occuring. In the case of the present invention, this problem does not arise since the surface of the lamp base is formed by the outer shell.Indeed, in the case ofthe lamp base 50 the outer shell as well asforming the outersurface alsoformsthe mould. Thus, a better quality finish on the outer surface of the article can be provided. Very often, when removing a moulded article from its mould, portions ofthe mouldable material break off, while in the case ofthe lamp base 50 this problem does not arise. In the case ofthe lamp bases 1 and 40 even if small chips break off the body member they will be concealed bythe outer shell.Where the method is used for producing a lamp base, particular advantages are achieved in that relatively lightweight materials which are attractive and pleasing to the eye may be used in the outershell, and at the same time, the lamp base is provided with a suitable weight to ensure stability of the base,thus avoiding ittopplingover.

Furthermore, by virtue of the fact that the outer shell can be relativelythin, materials which are relatively expensive may be used in forming the outer shell, since only a relatively thin film ofthe material is required.

Afurther advantage and a particuiarly important advantage ofthe invention is that by virtue ofthefact thatthe main body member is of ceramics material and is surrounded by an outer shell, it is unnecessary to fire the body member in a kiln. Once itisallowed to dry at room temperature,this is perfectly adequate. In fact, it has been found, in practice, that perfectly adequate drying can be achieved at room temperature in aboutfive days.

While particular shapes of lamp base have been described, it will be appreciated that lamp bases of many other shapes, construction and/or configurations could be manufactured using the methods ofthe invention without departing from the scope ofthe invention. Indeed, it will be appreciated that articles other than lamp bases may be provided according to the invention using the method ofthe invention. Further, it is envisaged in certain cases that an outer shell with an open mouth could be formed in one piece, and an end cap provided to close the open mouth.Alternatively, in certain cases, it is envisaged that an entirely closed shell could be provided in one piece, in this case the ceramics material could be injected into the shell through a small diameter opening, indeed, a hypodermic needle and syringe and the like could be used for injecting the ceramics material into the shell. In other cases it is envisaged that the shell may be formed in two halves.

Needless to say, it will be appreciated that materials other than PVC may be used for forming the outer shell, for example, an outer shell of any type of plastic material could be used without departing from the scope ofthe invention, and indeed, in certain cases it is envisaged that the outer shell may be provided by material other than plastics material. Further, in certain cases, it is envisaged that the outer shell may be provided by a moulding, such as an injection moulded shell, an extruded shell, a rotationally moulded shell or could be formed by any other suitable means. Indeed, in certain cases, it is envisaged thatthe outer shell may be of a light timber material, cardboard material or the like.

It is also envisaged that ceramics materials besides potters fine casting plaster may be used.

Indeed, it is envisaged that any type of casting clay may be used, such as earthenware, stoneware and the like. Of course, it will be appreciated that it is not necessary for a bore to be provided in the lamp base, and where a bore is provided, it need not be provided through the body member, in certain cases it could be provided through the body member and the outer shell.

It is also envisaged in certain cases that instead of vacuum forming the end caps or indeed forming them in one piece with the shell, they could be formed or manufactured using any other suitable process. In fact, in certain cases it is envisaged that the top and bottom end caps may be dispensed with altogether. In particular,the bottom end cap in certain cases could be dispensed with. Additionally, it is envisaged that the top and bottom end caps could be of material different to the material forming the side walls, or in certain cases, it is envisaged that the end caps may be of different colour material to the material forming the side walls, and indeed, in certain cases, it is envisaged that both end caps may be of different colours and they may also be of different colourto the material forming the side walls. Similar comments apply to the material of the end caps.

Needless to say, it will be appreciated that while relatively simple shapes with relatively simple cross sections have been illustrated, lamp bases or indeed any other articles with much more complex shapes and cross sections could be provided. Indeed, where the shell ofthe article is mouldedfrom a material, then extremely complex shapes could be achieved.

For example, figures of people, animals or any other types offigures could be moulded of a relatively light-weight shell which would, in general, have a relatively thin wall and the shell would then be filled with the mouldable material. Thus, the shells, by virtue ofthe fact that they could of relatively thin wall construction, could be formed of relatively expensive and exotic materials. This would then give the impression ofthe article being solidly formed from the material of the outer shell. Needless to say, it is not necessarythatthe outer shell should be of thin wall construction, it could be of a relatively thick wall construction.

Claims (44)

1. A method for forming an article of cera mics material comprising the steps of: forming a main body member ofthe article of ceramics material, surrounding the main body memberwith an outer shell.

2. A method as claimed in Claim 2 in which the main body member is moulded in a mould and allowed to set in the mould.

3. Amethod as claimed in Claim 1 inwhichthe main body member is removed from the mould and allowed to dry at room temperature.

4. A method as claimed in Claims 2 or3 in which the main body member is an elongated body member and a bore extending longitudinally through the main body member is formed during moulding.

5. A method as claimed in any preceding claim in which the method includes the step of partly forming the outer shell in sleeveform and sliding and bonding the outershell onto the main body member.

6. A method as claimed in Claim 5 in which the method includesthestepofformingthesleeve portion of the outer shell by forming the sleeve with four side walls from a sheet of material, the sheet of material being cutto size, and spaced apart fold lines being provided in the material corresponding to the corners ofthe side walls.

7. A method as claimed in Claim 6 in which the method includes the step of bonding an end capto the main body member and to the ends of the side walls,andforming an opening in the end capto communicate with the bore in the main body member.

8. A method as claimed in Claim 7 in which a second end cap is bonded to the other end ofthe body memberandto the ends ofthesidewalls.

9. A method as claimed in Claim 1 in which the method includesthestep of forming the outer shell of the article, forming the main body member in the outershell by moulding the ceramic material in the outer shell, and allowing the ceramic material to set in the outer shell.

10. A method as claimed in Claim 9 in which the method includes the step of forming the outer shell with an open mouth.

11. Amethod as claimed in Claim 10 in which the method includes the step of placing the outer shell in a support mould with the open mouth directed upwardly, and pouring the ceramic material mixed with water into the outer shell through the open mouth.

12. A method as claimed in Claim 10 or 11 in which an end cap is secured to the outer shell to close the open mouth.

13. A method as claimed in Claim 12 in which the end cap is secured by adhesive.

14. A method as claimed in any of Claims 9 to 13 in which the method includes the step of casting a removable plug in the ceramic material, and removing the plug when the ceramic material is set to form a hollow bore through the main body member.

15. Amethodasclaimedin Claim 14inwhicha holeisformedintheoutershelltocommunicate with the bore in the main body member.

16. Amethod as claimed in any of Claims 9to 15 in which the method includes the step of forming the outer shell having an outer side wall extending between a pair of spaced apart end caps.

17. A method as claimed in Claim 16 in which the method includes the step offorming the outer shell from a sheet of material forming spaced apartfold lines on the sheet of material, and bending the sheet of material along the fold lines to form fou r side walls.

18. A method as claimed in Claim 16 or 17 in which the method includes the step of forming the end caps by vacuum formation, the end caps having a base with upstanding side members.

19. A method for forming a lamp base, the method comprising the following steps: forming a main body member of ceramics material, forming part of an outershell in the form of a sleeve like member, and sliding and securing the sleeve-like member onto the main body member.

20. A method as claimed in Claim 19 in which the main body member is provided by an elongated body member, and a bore is cast longitudinally therethrough.

21. A method as claimed in Claim 20 in which a pair of end caps are secured to the ends ofthe main body member and to the ends of the sleeve-like member.

22. A method as claimed in Claim 21 in which the method comprises the step of forming an opening in one end cap to communicate with one end of the bore.

23. A method as claimed in Claim 22 in which an electrical cable is passed through the bore and through the opening in the end cap.

24. A method as claimed in Claim 23 in which a hole is drilled through the sleeve-like member, and the main body member to communicate with the bore, the electrical cable being passed through the hole.

25. A method as claimed in Claim 24 in which the second end cap is secured to the body member and the sleeve-like member after the electrical cable has been threaded through the bore.

26. A method as claimed in any of Claims 19 to 25 in which the method includes the step offorming the outersleeve-like memberfrom sheet material, the sheet material being cut to size, forming fold lines in the sheet material to define corners of side walls, and bending the sheet of material along the fold lines to form the side walls of the sleeve-like member.

27. A method as claimed in any preceding claim in which the outer shell is formed of sheet material.

28. A method as claimed in Claim 27 in which the sheet material is a plastics material.

29. A method as claimed in Claim 27 or 28 in which the sheet material is PVC.

30. A method as claimed in any preceding claim in which the ceramics material is casting clay.

31. A method as claimed in any preceding claim in which the ceramics material is potters fine casting plaster.

32. Amethodforforming a lamp base,the method comprising the steps of: forming an outer shell ofthe lamp base byforming a sheet of material to form a sidewall of an elongated outer shell ofthe lamp base, forming a pair of end caps of the outer shell, securing one ofthe end caps to the sidewall, placing the outer shell in a support mould with an open mouth facing upwardly, inserting a removable plug to form a hollow core in the outer shell, forming a main body member by moulding a ceramics material in the outer shell, allowing the ceramics material to set, removing the plug, removing the outer shell from the support mould, forming a hole through the outer shell to communicate with the bore, and securing the second end cap to the side wall to close the open mouth.

33. A method as claimed in Claim 32 in which the method includes the step offorming spaced apart fold lines in the sheet of material to form the side wall, and bending the sheetalongthefold linesto form a plurality of sidewalls.

34. Amethodforforming a lampbase,the method comprising the steps of: forming an elongated main body member of ceramics material with a bore extending therethrough, and securing an outer sleeve-like shell to the main body member.

35. An article formed according to the method of any ofthe preceding claims in which the article comprises an outer shell surrounding a main body memberformed of ceramics material.

36. An article as claimed in Claim 35 in which the outer shell comprises a sidewall extending between a pair of spaced apart end caps.

37. An article as claimed in Claim 36 in which a bore extends through the main body member between the end caps, a hole being provided in one of the end caps to communicate with the bore, and a second hole being provided through the side wall and the main body member to communicate with the bore.

38. An article as claimed in any of Claims 35 to 37 in which the outer shell is of PVC material and the main body member is of potters fine casting plaster.

39. An article as claimed in any of Claim 35 to 38 in which the article is a lamp base, and a nippleto secure a bulb holder is provided in one end cap engaging the bore.

40. An article as claimed in Claim 39 in which an electrical cable extends through the hole in the side wall into the bore and through the nipple.

41. An article as claimed in any of Claims 35to 40 in which the outer shell comprises four side walls.

42. Articles substantially as described herein with referenceto and as illustrated in the accompanying drawings.

43. Lamp bases substantially as described herein with reference to and as illustrated in the accompanying drawings.

44. A method for forming an article substantially as described herein with reference to and as illustrated in the accompanying drawings.