CN1295045C - Die casting machine with solid lubricant meter suitable for leading to phase change before lubricant being filled into injection cylinder - Google Patents

Abstract

The present invention relates to a die casting machine which comprises a meter enabling a plunger piston to be lubricated so as to undergo the phase change, wherein the meter is selectively provided with a lubricant for plunger pistons. The present invention relates to a method for lubricating a die casting machine, which relates to the implementation of the phase change in the lubricant for plunger pistons before the distribution of the lubricant for plunger pistons. The present invention also relates to a semifinished lubricant for plunger pistons, which undergoes the phase change in the meter.

Description

Die-casting machines with solid lubricant metering for causing a phase change before the lubricant is injected into the injection cylinder

technical field

The present invention relates to plunger lubricant and its application in die-casting process.

Background technique

Although the die casting process has been known for many years, problems still exist. A continuing problem relates to the area of plunger lubricants and other lubricants necessary for the efficient and low cost manufacture of die cast metal parts. Known lubricants present a range of environmental, safety and storage issues.

A die casting equipment usually includes a mold and an injection cylinder. The molten metal to be cast is introduced into the shot cylinder. A plunger extends axially into the shot cylinder to force molten metal into the mold. The shot pot and plunger require lubrication because the molten metal can weld itself to the shot pot and/or plunger and because the plunger can generate a lot of additional heat from friction as it rubs against the shot pot. Additionally, the lubricant helps prevent the plunger from unevenly rubbing against the inner walls of the injection cylinder. This uneven friction prevents smooth plunger movement and can lead to subnormal casting, which must be removed.

Uneven friction also leads to significantly increased wear and tear on the plunger and shot cylinder, which leads to increased downtime, repair costs, and even plunger replacement.

Various lubricants have been used in the past with less than satisfactory results. Oil-based lubricants are less favorable because they tend to smoke and decompose when they come into contact with molten metal or a shot cylinder that becomes hot from repeated use. Oil-based lubricants require a large warehouse space because they are bulky. Additionally, oil-based lubricants present a slippery and fall hazard if spilled on the floor.

Water-based lubricants avoid the smoking and decomposition of oil-based lubricants, but suffer from their own disadvantages. The main disadvantage is that the entrained water must be completely evaporated before being introduced into the molten metal as violent reactions may result if the molten metal comes into contact with the water. Water-based lubricants are typically injected into the injection cylinder by compressed air. The noise of the compressed air and the machinery used to generate the compressed air requires the use of noise-proof structures at additional expense. In addition, liquid lubricants require pumps and lines, which are prone to mechanical damage due to prolonged service life. Water-based lubricants typically include particulate material such as graphite or other inorganic particles that tend to agglomerate at or in the nozzle used to apply the lubricant. This reduces the reliability of the machinery used to apply the lubricant because the nozzles have to be cleaned regularly. In addition, local lubrication of the shot pot can be caused by partially clogging the nozzle, thus causing uneven friction of the plunger in the shot pot and its attendant problems. Water-based lubricants also require a lot of storage space because they are bulky.

Other types of lubricants that have been used include granular, powdered, and chipped solids. These suffer from the same drawbacks as water-based lubricants. Known granular lubricants tend to bounce off the ground during application and create a slip and fall hazard. Powder and flake lubricants may require complex additional machinery to effectuate their application, thus making their use more expensive and labor intensive. Also, due to their limited availability, such lubricants are more expensive than water-based lubricants.

Furthermore, all known lubricants suffer from severe purity problems. Known liquid lubricants tend to splash excessively when used. Known powder lubricants tend to create dusty working conditions. In either case, a great deal of time, energy, and money must be expended to keep the work area clean and safe as the splashed lubricant affects shutting off empty lubricant containers, creating unpleasant working conditions, and possibly a fire hazard.

Accordingly, the present inventors have recognized a need for improved lubricants for plungers and related processes for applying those lubricants that overcome one or more of these disadvantages.

Contents of the invention

The present invention relates to a die casting machine including a meter for subjecting a plunger lubricant to a phase change. The meter also dispenses plunger lubricant. The invention also relates to a method of lubricating a die casting machine involving effecting a phase change in the plunger lubricant prior to dispensing the plunger lubricant. The invention also relates to a plunger lubricant semi-finished product which undergoes a phase change in a meter.

Description of drawings

Figure 1 shows a pattern casting machine in which the present invention is utilized.

Detailed ways

Referring to FIG. 1 , a die casting machine 10 includes a horizontal cylindrical injection cylinder 12 . A plunger 14 is movable within the injection cylinder 12 from a retracted position (not shown) to an advanced position (not shown) adjacent to the die 16, the retracted position being shown in FIG. The die 16 includes two mold halves 18 and 20 which define a mold cavity 22 . The injection cylinder 12 is in fluid communication with the mold cavity 22 .

In operation, a lubricant according to the invention is added to the meter 24 . From the meter 24 the lubricant is introduced into the injection cylinder 12 through the pouring hole 26 . This is done at the beginning of each working cycle while the plunger 14 is in its retracted position as shown in FIG. 1 . The required amount of molten metal is then introduced into the shot cylinder 12 through the sprue hole 26 . The plunger 14 is then advanced in the direction of the die 16 until it blocks the pouring hole 26 . It then travels a further predetermined distance to inject molten metal into the mold cavity 22 . After a preset dwell time, which allows the molten metal to solidify, the die 16 is opened, and the plunger 14 then travels further to complete its full stroke, during which travel the casting is unloaded from the fixed half-mold 20 of the die. This also squeezes residual, solidified filler from the shot pot 12 . The plunger 14 is then retracted to the starting position, and the casting is ejected from the movable die half of the die. The die casting machine is then ready for another cycle.

The meter may include a silo in which the plunger lubricant is stored and contained in bulk prior to dispensing. One possible embodiment of the silo is shown at 28 in FIG. 1 . Any suitable meter may be used, the choice being emphasized on being able to provide a measured amount of plunger lubricant in an inexpensive manner. In a useful embodiment, the meter is a thermally fused meter. The gauge can be attached to the shot cylinder at the pouring hole. Alternatively, the gauge can be separated from the shot cylinder, as shown in Figure 1.

The meter may also include a nozzle to assist in dispensing plunger lubricant. Any type of nozzle can be used in conjunction with the meter. However, preferred nozzles are those that produce minimal splashing, dispense a measured amount of lubricant, while still achieving the desired form of lubricant distribution within the shot cylinder. For example, the nozzle may provide droplet, streamline, spread or mist, such as air atomized spread. A range of additional elements and methods are available to facilitate the delivery of plunger lubricant.

The plunger lubricant may be any lubricant suitable for the application in which the lubricant is to be used. Typical lubricable plunger materials are contemplated for use in the composition of the present invention. Preferred plunger lubricants are selected to have relatively low fuming, and are relatively inexpensive to produce, and relatively easy to add to the meter. A preferred plunger lubricant is a solid lubricant that has a melting temperature in the range of the operating temperature of the shot cylinder in which such lubricant is to be used.

Useful metal fatty acid salts include a number of sulfonates, naphthenates, and carbonyls. Among these metal fatty salts, fatty acid fatty acid salts such as zinc stearate and sodium stearate are preferable in view of their known properties, their easy availability and low price. However, other metal stearates known for their lubricating properties, including, by way of example only, tin, copper, titanium, lithium, calcium, manganese, and other fatty acid basic and strongly basic rare earth metal stearates are also may preferably be included.

Fatty acids may also be included, their lower cost, availability, and effect on the overall lubricity of the article making them attractive for this application. An example is stearic acid, which is conveniently used because it has good lubricity, is non-toxic, inexpensive and readily available.

Materials such as graphite, ceramic materials such as boron nitride, silicon nitride, or chromium carbide are useful additives to plunger lubricants, as is molybdenum sulfide.

Useful high melting polymer resins include, by way of example, polyethylene, polypropylene, polyvinyl chloride, polyvinyl alcohol, polyvinyl acetate cellulose, polyester, polyethylene glycol, polyacrylate, polymethacrylate , polystyrene, epoxy, silicone, polyamide and any of the above copolymer resins. In fact, almost any thermoplastic material can be used.

Of the natural and synthetic waxes that can be conveniently used, the higher molecular weight polyethylene waxes are generally considered to be the most lubricious. However, polypropylene, bisamides, ester microcrystals, beeswax, paraffin oil, oxides, complex polymers and heterosalt waxes are also preferred.

Glass materials useful in the present invention are preferably alumina, alumina/quartz, quartz or sodium borate. Alternatively, these glass materials can be used in chip fiber form. Diatomic minerals, talc, mica, other metal oxides, boric acid, wood flour, and phosphorus compounds, including phosphorus esters, are also useful.

The plunger lubricant can be in any form, shape and size that is convenient for use in a meter and/or addition to a silo. For example, preferred lubricants may be powders, granules, chips, or solid semi-finished products in the form of tubes, rods, disks, or small pieces. Alternatively, the lubricant may be a solid semi-finished product wound on a reel. Lubricant can be added to the silo using a variety of manual and automatic equipment, depending on the type, shape and size of the lubricant selected. Preferably, the plunger lubricant is a solid semi-finished product.

In operation, the meter facilitates a phase change in the lubricant from one phase state to another by providing the necessary operating conditions to cause a phase change in the plunger lubricant. The plunger lubricant, at least in part, undergoes at least one phase change after being added to the meter. This phase change occurs before or simultaneously with the plunger lubricant being dispensed. For convenience, these two cases will be considered as phase transitions occurring prior to being delivered. Although lubricants that change from a solid phase to a liquid phase are preferred, lubricants that change from a liquid to a solid phase are also useful.

Although a single phase change of the lubricant is preferred, the lubricant can undergo multiple phase changes such that the lubricant circulates between phases in the meter. In addition, the lubricant can undergo a partial phase change so that both phases exist side by side in the meter. Preferably, prior to dispensing, the plunger lubricant to be dispensed, ie the lubricant proximate the nozzle, has a substantially complete phase change from one phase state to the other, although complete phase change is not required. Alternatively, although the plunger lubricant is preferably in a single phase when dispensed, it is also possible to dispense plunger lubricants having two phases. This lubricant may be a combination of materials that melt and do not melt under normal operating conditions of the die casting machine.

After the lubricant in the meter reaches the proper phase or combination of phases, the meter dispenses the lubricant, preferably through a nozzle, into the shot cylinder. The lubricant may be in the same or a different phase when contained in the shot pot and when it is dispensed. In addition, the lubricant may also be in a combination of phases when it is contained in the shot cylinder. In one embodiment, the lubricant is liquid when it is contained in the shot cylinder and is dispensed as a liquid. In another embodiment, the lubricant is dispensed as a liquid but is solid when contained in the shot pot. In a third embodiment, the lubricant is dispensed as a liquid and has a solid shell with a liquid center when it is contained in the shot pot. In a fourth embodiment, the lubricant is dispensed as a combination of solid and liquid while it is liquid when contained in the shot cylinder. In a fifth embodiment, the lubricant is dispensed as a solid and liquid combination when it is contained in the shot cylinder. This embodiment covers combinations of materials that melt and do not melt under normal operating conditions of the die casting machine.

Although the invention has been particularly described in connection with certain specific embodiments thereof, it is to be understood that this is done by way of illustration and not of limitation, and the scope of the appended claims is to be construed as far as the prior art permits. as wide as possible.

Claims (18)

1. A die-casting machine, comprising: A meter adapted to phase-change, at least in part, the plunger lubricant in the first phase to the second phase and adapted to dispense the plunger lubricant to the injection cylinder. 2. The die casting machine of claim 1, further comprising a shot cylinder adapted to receive plunger lubricant from the meter. 3. Die casting machine according to claim 1, characterized in that the first phase is a solid and the second phase is a liquid. 4. The die casting machine of claim 1, wherein the meter is adapted to dispense plunger lubricant substantially in the second phase. 5. The die casting machine of claim 1, wherein the meter is adapted to dispense plunger lubricant in two phases. 6. Die casting machine according to claim 1, characterized in that the plunger lubricant is a solid semi-finished product. 7. The die casting machine of claim 1, wherein the meter includes a nozzle adapted to provide a metered amount of lubricant to the plunger. 8. Die-casting machine according to claim 7, characterized in that the nozzle is selected from the group consisting of nozzles producing droplet, streamline, scatter or mist and mixtures thereof. 9. The die casting machine of claim 1, wherein the nozzle further includes a hopper. 10. Die casting machine according to claim 1, characterized in that the plunger lubricant is adapted, at least partially, to undergo a second phase transition. 11. A method of lubricating a die casting machine, comprising: undergo a phase change in the plunger lubricant; and Dispensing plunger lubricant; The plunger lubricant is dispensed into the shot cylinder. 12. A method according to claim 11, characterized in that the phase transition is from solid to liquid. 13. The method of claim 11, further comprising performing a second phase change in the plunger lubricant. 14. The method of claim 11, wherein the step of dispensing further comprises dispensing the plunger lubricant in a manner selected from the group consisting of drops, streamlines, or spread. 15. The method of claim 11 wherein said step of effecting a phase change comprises melting the plunger lubricant. 16. A product of manufacture comprising: A plunger lubricant material that undergoes at least one phase change at least partially in the meter. 17. Product according to claim 16, characterized in that said raw material comprises natural wax or a synthetic wax. 18. Product according to claim 16, characterized in that said starting material comprises at least one material which is insoluble under normal operating conditions of the die-casting machine.