GB2287428A - Tool manufacture by moulding-machining - Google Patents

Description

1 2287428 The applicant has observed the need to equip high technology

installations and processes, such as in the aeronautical or automobile industry, with tools, equipment, matrices, etc., made of competitive materials in terms of mechanical features with metals, and which involve obvious advances as regards weight, recycling, repairs, etc.

The applicant has worked with copolymers of nylon, and has found that the intended goals are achieved with a copolymer obtained from opencut rough cast caprolactame subsequently machined to obtain the desired equipment.

Specifically, the invention refers to an equipment manufacturing process that is characterized by the combina tion in an opencut cast of a caprolactame and a prepolymer consisting of a caprolactame solution with acyl group radicals and polyoxypropylene radicals, using as catalyst a magnesium bromide solution in caprolactame, resulting in a rough cast copolymer that is machined to the desired tool shape.

The process covered by the invention is based on the following basic products:

E-Canrolactame.

Chemical formula Molecular weight Fusion point Melting point Density 30 Water content Acidity Alkalinity polyoxypropylene radicals.

viscosity 50-QC Acid level 2-Oxohexamethylenimine C,H1,0 N 113.16 69.2 268.5 1.02 0.015 0.05 0.05 Pl-30 PrelDolvmer.

C C gr/cm3 % in weight maximum neq/kg maximum neq/kg maximum Based on the caprolactame with acyl and 2,000 - 10,000 mPas meq/kg maximum 2 Cl Catalyst. Dissolution of magnesium bromide in caprolactame.

Extinction 390 nn 0.06 max.

Ether -- 100 Dpz maximum Fusion point Water content Acid level viscosity pH solvent is Water content 4 Demoulder B. Amide of a fatty acid.

139-1452C 0.04 in weight 270 meq/kg maximum Antifoam stabilizer.

2511C 800 to 1,600 cst to 8.5 0.5 in weight maximum Chemical reaction.

The caprolactame polymerizes by anionic polymerization.

The catalyst is a strong base that f orms links in the lactame. In the process, we use a cocatalyst (the prepolymer) to accelerate the reaction, where the catalyst is the third fundamental element.

Manufacturing process.

The parts are manuf actured in an open system at low pressure and polymerized within a f ew minutes.

This is one of the fundamental differences of the invention process in comparison to conventional methodology.

Material DreDaration.

The components are prepared in two stainless steel tanks named A and B. The materials are heated in an inert nitrogen atmosphere to up to 1201452C, depending on the formulation.

The cast is manufactured in one of the following materials:

Steel.

Machinable aluminum.

3 Cast aluminum.

cast iron.

Silicone.

Zamac.

The maximum cast filling time for pieces of up to 250 Kg. is 120 sec., depending on the percentage of catalyst. The cast is open type, i. e. without the upper cast cover. The material must be rapidly poured to prevent material polymerization and, as a result, the formation of layers during the filling process, e.g. pouring is carried out at more than 50 liters/minute.

The f inished piece should f oam at the top. This portion of the piece is machined once the piece has polymerized.

The manufacturing process is as follows:

a) Both the cast and the different components must be at a temperature exceeding ambient temperature, and for this reason they are preheated.

b) The casts must be clean and preheated.

c) The compositions of tanks A and B are located in two tanks differing in nitrogen atmosphere. The mixtures will have been previously weighed in accordance with the required amounts.

d) Both components are mixed in the cast. After 60 sec., the mixture begins to polymerize. The mixture temperature should be 120 to 1302 C. For annular parts, a prior mixture must be made by hand, in order to prevent the formation of an unpolymerized film on the portion opposite the material drop.

e) Once the heated pieces are withdrawn from the cast, they are put into a kind of rack so that they are not deformed during the cooling process. This implement may be made of epoxy, polyester or wood, although substances that may end up marking the raw material should always be avoided.

f) Thin pieces (less than 6 mm thick) 4 is need to be kept in this type of part until the temperature is lower than 702 C (crystal transition temperature) to free them of stresses. This usually takes some five minutes.

g) In the event that the cooling procedure does not conform with the above mentioned norms, high stresses are produced in the material, which cause breaks during the -machining process.

The general process is based on blocks without linear additives. In order to raise the CLTE (coefficient of linear thermal expansion) value, inorganic additives are used, for example from the family of fiberglasses that provide structural stiffness. The formulations admit quantities of fiber ranging from 10% to 40% without altering the other mechanical properties.

AiDiDlications in the aeronautic field.

Equipment manufacture.

To date, we have been able to conf irm the following results:

a) Tools manufactured with this type of material have performed in a similar way as metal tools in the f abrication of the f ollowing types of parts f or measuring and deep pressing:

- Benders for oil press (Becker) - Benders for rubber press (Pacific) p Deep pressing in mechanical and/or hydraulic press (Muller) - Pressing in free fall press - Drawing tools for Sheridan press.

In all cases, the material has produced parts as would any material of the aluminum or iron family. Neither cracks nor breaks of any kind have been detected in the internal or external tool structure.

Although the raw material price is similar to that of aluminum, the material density is 1. 16 gr/cm3, which means a notable weight reduction in relation to conventional equipment of aluminum (density 2.75) or ferric material (density 7.85) for the same part volume.

The material can be glued with conventional market adhesives of the cyanoacrylate series. This greatly facilitates the inclusion of modifications.

Pieces that are juxtaposed and glued to each other do not demonstrate any discontinuity in consecutive pressings throughout time. Neither do the plates obtained from these kinds of tools.

b) Milling tools.

Due to the possibility of precasting relatively large pieces, for the purpose of reducing weights and costs this type of material was very practical for making milling equipment. It accepted both vacuum and pressure pumps of up to 13 kg/cm2, and the dimensional stability made it possible to make any kind of tool for conventional machine tools.

Since milling tools require a high dimensional stability, they were loaded with a lower percentage of fiberglass.

c) Dual action pressing tools.

The male and female parts followed the design and manufacture of a conventional pressing tool. The press, including the brake nerves, reacted the same as in any metal die as regards obtainment of creases, lubrication, flange shaping and other peculiarities.

Guiding was done as usual with polyamide leads. In some cases, turrets of the same material were included. Selection of one or the other depended on the required die stiffness. In no case were there apparent differences between the two due to the material.

Pressings over 150 mm. were normal, especially in streamlines and leading edges. The material never revealed any weakness resulting from use in this type of structure.

Precast parts were always used initially with a constant overthickness of approximately B-10 mm. This permitted rough-hewn machining and short finishing times.

Applications in the automobile field.

6 a) Manufacture of preseries equipment. Both pressing and shaping dies are made in copolymer materials. Tool design is the usual for dual action dies: male and f emale parts in synthetic material and mobile press guided on polyamide leads or columns as required by the die stiffness.

The dies made to date have not revealed any type of weakness in terms of edge abrasion or breaking due to weakening. More than 5,000 pieces in 2. 00 mm thick plates pressed on this type of material have been produced without any apparent deformations.

Due to its density (1.16), the die weight is about one third of those made of aluminum, and a seventh of those manufactured with ferric materials.

Changes are very easy to make. it is simply necessary to machine a channel in the male and female parts of the zone to be modified. Another rough piece is then glued, with conventional glues of the cyanoacrylate family, to the contour of the above channel. The material with the new piece is put into the milling machine f or milling the modification by conventional methods.

This technique is very convenient and cheap f or making all sorts of parts f or impact/crash, saf ety deformation and aesthetic testing. With the obtained dies, it is possible to have parts during the design and engineering process without having to wait the months required to obtain final dies for a great deal of the necessary stamping work.

b) Equipment manufacture for previously shaped parts.

This is the case of:

a,,) Assembly line control models.

b,) Tools for modifications on already manufactured parts, e.g. sun roofs, insertion of fan elements in hoods, and in general all small and mediumsized parts that involve modifications on previous parts.

c.) Clamps and other corroding elements t A 7 is f or moving sheet metal during the welding and/or painting process.

c) Study equpiment.

In some cases, it may be advisable to manufacture a small series of parts to shorten development time of assembly processes on the assembly and/or welding lines. This type of material makes it possible to make definitive parts without having to wait for metal dies.

The material is supplied in blocks, plates or, in the case of simple geometric figures, preshaped moulds. This material accepts machining speeds of 15 meters per minute, and it is possible to rough hew at more than 50 mm. an operation. The shavings are clean and do not produce any kind of toxic smoke during the cutting process.

The finished parts are polished by hand or machine using conventional sandpaper. Final polishing is done by water polishing.

As indicated above, both the product itself and the shavings are fully recyclable.

8

Claims (13)

1. C L A I M S

   Equipment manufacturing process, characterized by combination in an opencast mould of a caprolactare and a prepolymer consisting of a caprolactame solution with acyl group radicials and polyoxypropylene radicals, and using a magnesium bromide solution in caprolactame as catalyst, resulting in a rough moulded copolymer that is machined to the desired tool shape.
2. 2. Equipment manufacturing process, according to the preceding claim, characterized by the fact that the components of the combination are previously heated in separate inert atmosphere tanks at a temperature of between 1202 and 1452 C.
3. 3. Equipment manufacturing process, according to the preceding claims, characterized by the fact that a fatty acid amide is used as casting agent.
4. 4. Equipment manufacturing process, as per the preceding claims, characterized by the fact that pouring speed from tanks to cast exceeds 50 1/minute.
5. 5. Equipment manufacturing process, according to the preceding claims, characterized by the fact that inorganic loads are added to the combination to increase structural resistance.
6. 6. Equipment manufacturing process, according to the preceding claims, characterized by the fact that before casting, the moulds are heated.
7. 7. Equipment manufacturing process, according to the preceding claims, characterized by the fact that the cast copolymer is put onto a rack to prevent deformation during cooling.
8. 8. Equipment manufacturing process, according to the preceding claims, characterized by the fact that the machined tool is polished with sandpaper.
9. 9. Equipment manufacturing process, according to the preceding claims, characterized by the fact that the shape of the mould is almost the same as the finished tool.

   Ir k 9
10. 10. An article made by taking an opencast mould; combining therein a caprolactame and a prepolymer consisting of a caprolactame solution with acyl group radicals and polyoxypropylene radicals in the presence of a catalyst comprising a magnesium bromide solution in caprolactame; and machining the resulting rough moulded copolymer.
11. 11. An article according to claim 10 comprising a die, mould or tool.
12. 12. Equipment manufacturing process according to claim 1 and substantially as hereinbefore described.
13. 13. An article according to claim 10 and substantially as hereinbefore described.