MXPA04008188A

MXPA04008188A - Die casting machine with dispenser for solid lubricant, adapted to cause phase change of the lubricant prior to be dispensed to the shot sleeve.

Info

Publication number: MXPA04008188A
Application number: MXPA04008188A
Authority: MX
Inventors: Edwards Dean
Original assignee: Chem Trend Inc
Priority date: 2002-02-21
Filing date: 2002-02-21
Publication date: 2005-05-17
Also published as: CN1620347A; WO2003072283A1; JP2005518282A; KR20050004783A; EP1476263A1; BR0215600A; AU2002244100A1; CA2477007A1; CN1295045C

Abstract

The present invention relates to a die casting machine which includes a dispenser that causes a plunger lubricant to undergo a phase change. The dispenser also dispenses the plunger lubricant. The present invention also relates to a method of lubricating a die casting machine which involves effecting a phase change in the plunger lubricant prior to dispensing the plunger lubricant. The present invention also relates to a plunger lubricant blank which under goes a phase change in the dispenser.

Description

- MOLDING MACHINE IN MATRIX WITH DOSER FOR SOLID LUBRICANT, ADAPTED TO CAUSE A PHASE CHANGE OF THE LUBRICANT BEFORE BEING DOSE TO THE SLEEVE FEEDING FIELD OF THE INVENTION This invention relates to piston lubricants and their use in matrix molding processes.

BACKGROUND OF THE INVENTION Although matrix molding procedures have been known for many years, there are still problems. One of the continuing problems relates to the area of piston lubricants and other lubricants necessary for the efficient and cost-effective manufacture of molded metal parts on matrix. The known lubricants have various environmental, safety and maintenance drawbacks. A matrix molding apparatus generally comprises a die and a feeding sleeve. The molten metal to be molded is introduced into the feed sleeve. A plunger extends axially within the feed sleeve to push the molten metal into the die. The feeding sleeve and the plunger require lubrication because the molten metal itself can solidify in the feed sleeve or the plunger and because the plunger can generate significant amounts of additional heat by friction as it rubs against the sleeve. feeding. In addition, the lubricants help prevent the plunger from rubbing irregularly against the inner wall of the feed sleeve. Irregular rubbing prevents a uniform movement of the plunger that can result in a lower quality molding, which must be discarded. Irregular rubbing also results in significantly increased wear and tear of the plunger and feed sleeve, resulting in an increase in waste time in repairs, repair costs and finally the need to replace the plunger. In the past, various types of lubricants have been used with less than satisfactory results. Oil-based lubricants are not favored because they tend to generate smoke and degrade when they come into contact with the molten metal or the feed hose that is hot from repeated use. Oil-based lubricants require large amounts of warehouse space because they are bulky. In addition, oil-based lubricants present slip and fall hazards if splashed onto the floor. Water-based lubricants prevent the formation of smoke and degradation of oil-based lubricants, but suffer from their own drawbacks. The main drawback is that the carrier water must completely evaporate before the introduction of the molten metal because a violent reaction can be generated if the molten metal is brought into contact with water. Water-based lubricants are typically sprayed on the hot hose through the use of compressed air. The noise of the compressed air and the machinery used to produce the compressed air requires the use of noise-proof structures with additional concomitant costs. In addition, liquid lubricants require pumps and tubes which are susceptible to mechanical failure for extended periods of use. Water-based lubricants often include particulate materials such as graphite or other inorganic particles that tend to coagulate in or within the spray nozzle used to apply the lubricant. This decreases the reliability of the machinery used to apply the lubricant because the nozzle must be cleaned periodically. In addition, it can be obtained as - - partial lubrication of the feeding sleeve results from a partially blocked nozzle, which generates an irregular rubbing of the plunger in the feeding sleeve and its concomitant problems. Water-based lubricants also require large amounts of storage space because they are bulky. Other types of lubricants have been used, including solids in the form of pellets, powders and scales. They present some of the same flaws as water-based lubricants. Lubricants known as pellets tend to jump on the floor during application and create the danger of slipping and falling. Powder and flake lubricants may require complicated additional machinery to carry out their use, which makes their use more expensive and requires more work. In addition, lubricating materials can be more expensive than water-based materials due to their limited availability. In addition, all known lubricants suffer from serious cleaning problems. Known liquid lubricants tend to splash excessively when applied. A known spray lubricant tends to create working conditions with dust. In any case, significant amounts of time, energy and money must be spent to keep the work area clean and safe because spilled lubricants interfere with the change of empty lubricant containers, create unpleasant working conditions and can be a hazard. of fire. Accordingly, the inventor has recognized the need to improve the piston lubricants and associated methods of application of said lubricants, and this invention solves one or more of these drawbacks.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a matrix molding machine which includes a metering device which causes the piston lubricant to undergo a phase change. The doser also doses the piston lubricant. The present invention also relates to a method for lubricating a matrix molding machine that involves carrying out a phase change in the piston lubricant before dosing in piston lubricant. The present invention also relates to a design of a piston lubricant which undergoes a phase change in the dispenser.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a matrix molding machine in which the present invention can be used.

DETAILED DESCRIPTION With reference to Figure 1, a matrix molding machine 10 includes a horizontal cylindrical feed sleeve 12. A plunger 14 can be moved between the feeding sleeve 12 from a retracted position, which is shown in Figure 1, to an advanced position (not shown) close to a matrix 16. The matrix 16 comprises matrix halves 18 and 20 defining a die cavity 22. The feeding sleeve 12 is in fluid communication with the die cavity 22. In operation, a lubricant according to the present invention is loaded in a dispenser 24. From the dispenser 24 the lubricant is introduced into the feed sleeve 12 through a pouring orifice 26. This is done at the beginning of each operation cycle, while the plunger 14 is in its retracted position, as shown in Figure 1. The desired amount of molten metal is then introduced into the feed sleeve 12 through the orifice 26. of pouring. The plunger 14 is then advanced forward in the direction of the die 16 until it blocks the pouring orifice 26. Then, further advancement is made at a predetermined distance, by injecting the molten metal into the cavity 22 of the matrix. After a pre-set waiting time, which allows the molten metal to solidify, the matrix 16 is opened and the plunger 14 is further advanced to complete its total stroke in which the molding is released from the stationary half of the die. This also drives the residual solidified plug from the feed sleeve 12. The plunger 14 is then retracted to a starting position and the molding is ejected from the movable half 18 of the die. The machine is then ready for another cycle. The dispenser may include a hopper where the piston lubricant is received and stored in bulk before being dosed. A possible embodiment of a hopper is shown in Figure 1 with the reference number 28. Any suitable dispenser can be used with emphasis placed on that by selecting one that provides a measured quantity of plunger lubricants in a manner that is not costly. In a useful mode, the doser is a doser that melts hot. The doser can be connected to the feed hose in the pouring orifice. Alternatively, the dispenser may be separate from the supply sleeve, as shown in Figure 1. The dispenser may also include a nozzle to aid in the metering of the piston lubricant. Any nozzle can be used together with the dispenser. However, the preferred nozzles are those which generate a minimum amount of splashing, dose a measured amount of lubricant and also obtain the desired pattern of lubricant coverage within the feed sleeve. For example, the nozzle may provide the lubricant in a drip, in a stream, in a spray or in a mist such as an atomized spray of air. Various components and additional methodologies can be used to facilitate the metering of the piston lubricant. The piston lubricant can be any lubricant suitable for the application in which the lubricant is to be used. Typical materials which are capable of lubricating the feeding sleeve are contemplated for use in the composition of the invention. The preferred plunger lubricant is selected to generate relatively little smoke, be relatively inexpensive to manufacture and relatively easy to load inside the dispenser. A preferred plunger lubricant is a solid lubricant which has a melting temperature in the range of operating temperatures of the feed hose in which the lubricant is to be used. By way of example only, the lubricants may include metal soaps, fatty acids, graphite, ceramic materials, polymer resins with high melting temperature, natural and synthetic waxes, gilsonite, glass and mixtures of these materials. Useful metal soaps include many sulfonates, naphthenates and carboxylates. Of these, fatty acid soaps such as zinc stearate and sodium stearate are preferred when taking into account their own properties, their easy availability and their low cost. However, other metal soaps known for their lubricating properties including, by way of example only, tin, copper, titanium, lithium, calcium, magnesium and other alkaline and alkaline earth metal soaps of the fatty acids can be advantageously included. Fatty acids can also be included and their relatively low cost, easy availability and contribution to the overall lubricity of the composition make them attractive for such use. An example is stearic acid, which is advantageously used since it has good lubricating properties, is non-toxic, is inexpensive and is readily available. Materials such as graphite and ceramic materials such as boron nitride, silicon nitrate or chromium carbide are useful for additives to piston lubricants, as well as in molybdenum sulfides. Polymer resins with a high melting temperature include, for example, polyethylene, polypropylenes, polyvinyl chlorides, polyvinyl alcohols, polyvinyl acetate of celluloses, polyesters, polyethylene glycols, polyactylates, polymethacrylates, polystyrenes, epoxy resins, silicone resins, polyamides and any copolymer resin of the above. Actually, you can use almost any thermoplastic material. Of the natural and synthetic waxes that can be used advantageously, polyethylene waxes of relatively high molecular weights are generally preferred when taking into consideration the lubricity they impart. However, polypropylene, bisamide, ester, microscrystalline material, beeswax, paraffin, oxidized material, copolymers and meat-flesh waxes are also preferred. Vitreous materials useful in the present invention are preferably alumina, alumina / silica, silica or borax. Optionally, these vitreous materials can be used in the form of staple fibers. Diatomaceous earth, talc, mica or other metal oxides, boric acid, sawdust and phosphorus compounds including phosphate esters may also be useful. The plunger lubricant may be in the conformation, shape and size that is convenient for it to be used in the dispenser or for it to be loaded in the hopper. For example. Preferred lubricants can be a powder, a particulate material, a flake or a solid preform, in a conformation of a tube, a rod, a disc or a brick. In addition, the lubricant can be a solid preform wound on a coil. Depending on the shape, shape and size of the selected lubricant, a variety of manual and automatic devices can be used to load the lubricant into the hopper. Preferably, the piston lubricant is a solid preform. In operation, the metering device performs a phase change of the piston lubricant by providing the operating conditions necessary to promote a phase change from a phase state to another phase state in the lubricant. The piston lubricant at least partially experiences at least one phase change after it is loaded into the dispenser. The phase change is carried out before or simultaneously with the supplied piston lubricant. For convenience, both situations are referred to as the phase change that takes place before it is delivered. Although lubricants with phase change from solid to liquid are preferred, lubricants with phase change from liquid to solid are also contemplated. Although a single phase change for the lubricant is preferred, the lubricants may also undergo multiple phase changes so that the lubricant cycles between the phases while in the dispenser. In addition, the lubricants may undergo partial phase changes so that two phase states exist concurrently in the dispenser. Preferably, prior to dosing, the plunger lubricant which is ready to be metered, i.e., the lubricant that is near the nozzle, has substantially completed the phase change from one phase state to another phase state, although a complete phase change is not required. Stated another way, while it is preferred that the piston lubricant be in a single phase state when it is supplied, the piston lubricant which has two phase states can also be supplied. Such lubricants can be a combination of materials that melt and which do not melt under normal operating conditions for matrix molding machines. After the appropriate phase state, or the combination of phase states, that the lubricant has reached in the dispenser, the dispenser supplies the lubricant, preferably through a nozzle, into the feed sleeve. When the lubricant is received in the feed sleeve, it may have a phase state equal to or different from that which it presents when dosed. In addition, the lubricant may also be in a combination of phase states when it is received in the feed sleeve. In one embodiment, the lubricant is dosed as a liquid and is a liquid when it is received in the feed sleeve. In another embodiment, the lubricant is dosed as liquid and is a solid when it is received in the feed sleeve. In a third embodiment, the lubricant is supplied as a liquid and has a solid cover with a liquid center when it is received in the feed sleeve. In a fourth embodiment, the lubricant is supplied as a combination of solid and liquid and is a liquid when received in the feed sleeve. In a fifth embodiment, the lubricant is supplied as a combination of solid and liquid and is a combination of solid and liquid when received in the feed sleeve.

This modality covers lubricants which can be a combination of materials which melt and which do not melt under normal operating conditions for matrix molding machines. Although the invention has been specifically described in relation to certain specific embodiments thereof, it should be understood that this is by way of illustration and not limitation, and that the scope of the appended claims should be broadly considered as allowed by the prior art.

Claims

1. A matrix molding machine, comprising: a dispenser adapted to cause a piston lubricant in a first phase state to at least partially experience a phase change to a second phase state and which is adapted to dose the piston lubricant to a feed hose.

2. The matrix molding machine, as described in claim 1, further comprising a feeding sleeve adapted to receive the piston lubricant from the dispenser.

3. The matrix molding machine, as described in claim 1, wherein the first phase state is solid and the second phase state is liquid.

4. The matrix molding machine, as described in claim 1, wherein the dispenser is adapted to dose the piston lubricant substantially in the second phase state.

5. The matrix molding machine, as described in claim 1, wherein the dispenser is adapted to dose the piston lubricant in two phase states.

6. The matrix molding machine, as described in claim 1, wherein the piston lubricant is a solid preform. The matrix molding machine, as described in claim 1, wherein the dispenser includes a nozzle adapted to provide a measured quantity of the piston lubricant. 8. The matrix molding machine, as described in claim 7, wherein the nozzle is selected from the group consisting of a drip nozzle, a stream nozzle or a spray nozzle. 9. The matrix molding machine, as described in claim 1, wherein the dispenser further includes a hopper. 10. The matrix molding machine, as described in claim 1, wherein the plunger lubricant is adapted to undergo, at least partially, a second phase change. The matrix molding machine, as described in claim 1, wherein the doser and the feeding sleeve are adapted to prevent a second phase change in the piston lubricant. 12. A matrix molding machine, comprising: a dispenser adapted to cause a plunger lubricant in a first phase state to at least partially experience a phase change to a second phase state and adapted to supply the piston lubricant; and a feeding sleeve adapted to receive the piston lubricant of the dispenser. 13. A method of lubricating a matrix molding machine, comprising: producing a phase change in a piston lubricant; and dose the piston lubricant. The method as described in claim 13, wherein the plunger lubricant is supplied in a feed sleeve. 15. The method as described in claim 13, wherein the step of performing is carried out before the dosing step. 16. The method as described in claim 13, wherein the step of performing occurs simultaneously in the dosing step. 1

7. The method as described in claim 13, wherein the phase change is from solid to liquid. 1

8. The method as described in claim 13, further comprising carrying out a second phase change in the piston lubricant. 1

9. The method as recited in claim 13, wherein the supplying step further includes supplying the plunger lubricant in a manner selected from the group consisting of drip, stream or spray. The method as described in claim 13, wherein the embodiment further includes melting the piston lubricant. 21. A manufacturing article, comprising: a plunger lubricant preform which experiences, at least partially, at least one phase change in a dispenser. 22. The article as described in claim 21, wherein the preform undergoes a phase change from solid to liquid. 23. The article as described in claim 21, wherein the preform includes a natural wax or a synthetic wax. 24. The article as described in claim 21, wherein the preform includes at least one material which does not melt under normal operating conditions for matrix molding machines.