GB1583048A

GB1583048A - Method of assembling mould parts to form a whole mould for casting metal

Info

Publication number: GB1583048A
Application number: GB34472/77A
Authority: GB
Original assignee: KOHLSWA JERNVERKS AB
Current assignee: KOHLSWA JERNVERKS AB
Priority date: 1976-08-18
Filing date: 1977-08-17
Publication date: 1981-01-21
Also published as: NO772842L; DK367277A; NO149686B; FR2361955A1; FR2361955B1; DK146758B; FI772441A; FI60657B; DK146758C; FI60657C; NO149686C

Description

(54) METHOD OF ASSEMBLING MOULD PARTS TO FORM A WHOLE MOULD FOR CASTING METAL (71) We, KOHLSWA JERNWERKS AB., a Swedish body corporate of Kolsva, Sweden, 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:- When assembling mould parts to form a whole mould for casting metal, for example cast iron, cast steel, light metals and bronzes, the mould parts are sometimes glued to gether along their contacting surfaces.Since the moulding material in the region of a glued joint often does not have sufficient strength to withstand the load exerted by the metal during casting and solidification, the joint or joints between the mould parts must be strengthened, for example by plac ing weights on top of an upper mould part, by using clamping devices on the mould parts or by embedding the mould parts in a material which presses the mould parts towards each other. If an efficient joining is not achieved, the castings produced will have dimensional faults, flashes or other defects caused by unsatisfactory joining of the mould parts. In addition, the castings may have internal faults because the molten metal has not sufficed to fill up the mould completely.

The present invention aims to provide a method of achieving an efficient and tight securing together of mould parts without the use of the previously mentioned weighting and/or clamping so that castings of a high quality can be manufactured without the dimensional faults, flashes and other defects mentioned above.

According to the invention, a method of joining together mould parts to form a whole mould for casting metal, is characterised in that, in the manufacture of the mould parts, connecting bodies with exposed surfaces are moulded in at portions of the mould parts which are to face each other in the assembled mould, and in that exposed surfaces of the connecting bodies in mould parts arranged adjacent to each other are arranged facing each other and- are glued to each other when the mould parts are assembled to form the whole mould.

The connecting bodies should be of a material of higher strength than the material of the mould parts when the latter are ready for casting. The connecting bodies which are glued together may, if they consist, for ex ample, of steel, be retrieved when knocking out the castings from the moulds, so that after breaking down the glue, for example by heat treatment, they may be used again.

If the connecting bodies consist of a cheap plastics material or wood, it may be suitable to use them once and then discard them.

Connecting bodies of plastics material are particularly preferred. The connecting bodies may be placed at a relatively great distance from the casting cavity of the mould, and therefore there is no risk that organic material will melt or be destroyed in some other way. Connecting bodies of plastics material may suitably be injection-moulded, for example from PVC, or they may be compression-moulded and reinforced, for ex ample from phenol resin reinforced with paper or glass fibre.

In a particularly advantageous embodi ment of the method of the invention, one mould part has connecting bodies moulded into it, each provided with an anchoring part for anchoring the connecting body in this mould part, and either with a female or male part with an exposed surface which matches an exposed surface of the male or female part, respectively, of a connecting body which is moulded in, and is anchored by an anchoring part in, another mould part. Alternatively, each of two mould parts may be provided with connecting bodies each having an anchoring part and a female part, the two mould parts being joined together using a double male part in the form of a separate body with an exposed surface which matches exposed surfaces of the female parts of the two mould parts.

Preferably, in the above-mentioned cases, the connecting bodies are provided with anchoring parts having a greater lateral extension than the female and male parts.

In another embodiment of the invention the connecting bodies consist of plates which are moulded into the mould parts, during manufacture of the latter, with outwardlyfacing surfaces exposed. The exposed surfaces of these plates in abutting mould parts are arranged facing each other and glued to each other during the assembly of the mould parts to form the whole mould.

To achieve an effective anchoring of the plates in the mould parts in the last mentioned embodiment, the plates may be provided with anchoring parts which extend into the interior of the mould parts. According to one embodiment these anchoring parts are made in the form of shafts. A number of other designs of the anchoring parts are possible, for example, discs, flanges, rings, etc. In certain cases it may also be an advantage to make these anchoring parts flexible or movable to facilitate a complete mould filling. Again, when using plates as the connecting bodies, at least some of the plates abutting each other in adjacent mould parts may be formed with a male and female part, respectively, for guiding the mould parts with respect to each other.

The method according to the invention may be applied to moulds having mould parts manufactured from all types of moulding material used in the foundry technique.

For the gluing together of the exposed surfaces of the connecting bodies there may be used a glue which is conventionally used for gluing the material from which the bodies are made. Glue in the form of a resinous binder, which hardens at room temperature, is preferred, for example epoxy resins, polyurethane resins and epoxy resins modified with polyamides, phenol resins or polyurethane resins. It is also possible to use a glue of inorganic type.

The invention will now be described by way of example, with reference to the accompanying drawings, in which Figures 1 to 3 are sectional views of two mould parts joined together by three different embodiments of the method according to the invention, and Figure 4 is a sectional view of two mould parts joined together by connecting bodies in the form of plates provided with guiding members.

A moulding material is prepared from quartz sand of medium grain size (approximately 0.25 mm). The sand is first mixed with 0.4 per cent by weight (calculated on the sand) of an ester hardener consisting of a mixture of equal parts of diacetine and triacetine and thereafter with 4 per cent by weight (calculated on the sand) of water glass (sodium silicate) containing 40 per cent by weight of silicate and 60 per cent by weight of water. Mould parts 10 and 11, respectively, of a block mould according to Figure 1 are manufactured from this moulding material by consolidating the moulding material around patterns on a pattern board with connecting bodies 12, 13, 14 and 15 of PVC arranged at the sides of the patterns. Each connecting body has a substantially frusto-conical anchoring part 12a, 13a, 14u and 15a, respectively, for securing the body to the mould part.The anchoring parts are also provided with shoulders 12b, 13b, 14b and 15b, respectively, for strengthening their anchorage. The connecting bodies 12 and 13 have a cylindrical female part 1 2c and 13c, respectively and the connecting bodies 14 and 15 a cylindrical male part 1 4c and 15c, respectively. The cylindrical inner surfaces of the female parts 1 2c and 13c, which are exposed prior to the joining of the mould parts, fit the exposed cylindrical outer surfaces of the parts 14c and l5c. For each mould part the Figures show only two connecting bodies.

Normally there are several connecting bodies, evenly distributed around the pattern. The pattern board with its patterns, which is provided with fastening devices, for example pigs, for the female parts 12c and 13c in bodies 12 and 13 and holes for the male parts 14c and 15c in bodies 14 and 15, is suitably vibrated or rammed when the moulding material is applied. When the mould parts have been cured for 15-30 minutes the patterns can be withdrawn, the connecting bodies then being anchored in the respective mould parts.After some addi tional hours of curing, the mould parts 10 and 11 are put together, and the cylindrical inner surfaces of the female parts 12c and 1 3c and the mating cylindrical outer surfaces of the male parts 1 4c and 1 sic are glued together, for example with a cold-setting polyurethane glue (such as Plastic Mastic No. 573.8 with hardener Kleiberit B8 from Klebchemie, Germany). The surfaces of the mould parts 10 and 11 facing each other make contact with each other after the assembly.

Casting metal into the mould, for ex ample steel, is normally carried out at least six hours after withdrawing the pattern.

The ingate is designated 16. The cast mould is held together by the adhesive force at the glued connecting bodies during the entire casting and solidification process. After knocking out the cast mould, a casting of high quality without dimensional faults, flashes and other defects is obtained.

If, for example, a furan resin is used as the binder in the above example, instead of water glass, in an amount (including hardener) of 2 per cent by weight (calculated on the sand), the pattern may be withdrawn after 10 minutes, the mould parts may be assembled after half an hour and the casting may be performed at least 2 hours after withdrawal of the pattern.

Figure 2 shows the use of two mould parts 10 and 10', respectively, in which the connecting bodies 12, 13, 12' and 13', respectively, all have female parts 12c, 13c, 1 2'c and 1 3'c, respectively, of the same type as those in the mould part 10 of Figure 1. When joining together the mould parts 10 and 10', the female parts 12c, 13c, 12'c and 1 3'c, respectively, are glued together with double male parts in the form of separate bodies 17 and 18, respectively, of PVC.

The upper portions of the cylindrical outer surfaces of the parts 17 and 18 are then glued to the cylindrical inner surfaces of the female parts 1 2c and 13c, respectively, and the lower portions of the cylindrical outer surfaces of the parts 17 and 18 are glued to the cylindrical inner surfaces of the female parts 12'c and 13'c, respectively.

The male and female parts in the connecting bodies need not be of cylindrical shape. They may, among other things, be conical, spherical or parallelepipedic. Similarly, the anchoring parts need not be of frusto-conical shape. However, it is a great advantage if the anchoring parts have a greater lateral extension than the female and male parts. Along other things, the anchoring parts may be in the form of one or more rods or shafts extending into the mould part, preferably more or less in the lateral direction.

Figure 3 shows the use of connecting bodies in the form of plates 22, 23, 24 and 25 with anchoring parts in the form of shafts 26, 27, 28 and 29 extending into the moulding material. The mould parts are glued together where the plates 22 and 23 in the mould part 10 make contact with the plates 24 and 25 in the mould part 11. The other parts of the surfaces of mould parts 10 and 11 facing each other also make contact with each other.

Figure 4 illustrates the use of connecting bodies in the form of plates which are provided with guiding members. A plate 22a with shafts 26 in the upper mould part 10 is formed with a hole 31 and a plate 24a with shafts 28a in the lower mould part 11 is formed with a frusto-conical peg 32. The maximum diameter of the peg is substantially the same as the diameter of hole 31.

WHAT WE CLAIM IS: 1. A method of joining together mould parts to form a whole mould for casting metal, characterised in that, in the manufacture of the mould parts, connecting bodies with exposed surfaces are moulded in at portions of the mould parts which are to face each other in the assembled mould, and in that exposed surfaces of the connecting bodies in mould parts arranged adjacent to each other are arranged facing each other and are glued to each other when the mould parts are assembled to form the whole mould.

2. A method according to claim 1, in which one mould part has connecting bodies each provided with an anchoring part for anchoring the connecting body in this mould part, and either with a female or male part with an exposed surface which matches an exposed surface of the male or female part, respectively, of a connecting body which is moulded in, and is anchored by an anchoring part in, another mould part.

3. A method according to claim 1, in which each of two mould parts is provided with connecting bodies each having an anchoring part and a female part, the two mould parts being joined together using a double male part in the form of a separate body with an exposed surface which matches exposed surfaces of the female parts of the two mould parts.

4. A method according to claim 2 or 3, in which the anchoring part of a connecting body has a greater extension in the lateral direction than its female or male part.

5. A method according to claim 1, in which connecting bodies in the form of plates are moulded into the mould parts, during manufacture of the latter, with outwardly-facing surfaces exposed, the exposed surfaces of plates in abutting mould parts being arranged to abut each other and being glued to each other during assembly of the mould parts to form the whole mould.

6. A method according to claim 5, in which at least some of the plates are provided with anchoring parts in the form of shafts extending into the interior of the mould parts.

7. A method according to claim 5 or 6, in which at least some of the plates facing each other in adjacent mould parts are formed with a male or female part, respectively, for guiding the mould parts with respect to each other.

8. A method according to any of claims 5 to 7, in which at least some of the plates are provided with flexible or movable anchoring parts extending into the interior of the mould parts to anchor the plates to the mould parts.

9. A method of joining together mould parts to form a whole mould for casting metal, substantially as herein described with

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. parts 10 and 10', respectively, in which the connecting bodies 12, 13, 12' and 13', respectively, all have female parts 12c, 13c, 1 2'c and 1 3'c, respectively, of the same type as those in the mould part 10 of Figure 1. When joining together the mould parts 10 and 10', the female parts 12c, 13c, 12'c and 1 3'c, respectively, are glued together with double male parts in the form of separate bodies 17 and 18, respectively, of PVC. The upper portions of the cylindrical outer surfaces of the parts 17 and 18 are then glued to the cylindrical inner surfaces of the female parts 1 2c and 13c, respectively, and the lower portions of the cylindrical outer surfaces of the parts 17 and 18 are glued to the cylindrical inner surfaces of the female parts 12'c and 13'c, respectively. The male and female parts in the connecting bodies need not be of cylindrical shape. They may, among other things, be conical, spherical or parallelepipedic. Similarly, the anchoring parts need not be of frusto-conical shape. However, it is a great advantage if the anchoring parts have a greater lateral extension than the female and male parts. Along other things, the anchoring parts may be in the form of one or more rods or shafts extending into the mould part, preferably more or less in the lateral direction. Figure 3 shows the use of connecting bodies in the form of plates 22, 23, 24 and 25 with anchoring parts in the form of shafts 26, 27, 28 and 29 extending into the moulding material. The mould parts are glued together where the plates 22 and 23 in the mould part 10 make contact with the plates 24 and 25 in the mould part 11. The other parts of the surfaces of mould parts 10 and 11 facing each other also make contact with each other. Figure 4 illustrates the use of connecting bodies in the form of plates which are provided with guiding members. A plate 22a with shafts 26 in the upper mould part 10 is formed with a hole 31 and a plate 24a with shafts 28a in the lower mould part 11 is formed with a frusto-conical peg 32. The maximum diameter of the peg is substantially the same as the diameter of hole 31. WHAT WE CLAIM IS:

1. A method of joining together mould parts to form a whole mould for casting metal, characterised in that, in the manufacture of the mould parts, connecting bodies with exposed surfaces are moulded in at portions of the mould parts which are to face each other in the assembled mould, and in that exposed surfaces of the connecting bodies in mould parts arranged adjacent to each other are arranged facing each other and are glued to each other when the mould parts are assembled to form the whole mould.

reference to any of Figures 1 to 4 of the accompanying drawings.

10. A metal-casting mould when made by the method claimed in any of the preceding claims.