TW201542337A - Self-lubricating composite material and method for the production thereof - Google Patents

Abstract

The invention relates to a method (21) for producing a self-lubricating composite material, wherein a powdery primary metal material is mixed with a likewise powdery secondary material, and the mixture (3) is subjected to a hot-isostatic pressing process (28). In order to do so, the mixture of the primary material and secondary material is filled into a shaping mold, and the mold is evacuated, whereupon the actual hot-isostatic pressing process is carried out. This makes it possible to obtain a substantially compact desired material.

Description

Self-wetting composite material and manufacturing method thereof

The present invention relates to a method of making a self-lubricating composite. The invention further relates to a self-lubricating composite, the use of a self-lubricating composite, and a mechanical device.

The use of solid lubricants (solid lubricants) in today's technology has become commonplace in some areas. An example of a solid lubricant is, for example, graphite or molybdenum disulfide. Such solid lubricants basically perform similar functions as well-known liquid lubricants, particularly lubricating oils. However, the advantage of solid lubricants is that they have a longer life, in particular under certain environmental conditions, since they do not, or at least to a lesser extent, evaporate from the surface to be lubricated, or in this case via the dissolution process. Sometimes solid lubricants, in addition to being used for lubrication, are used in reverse to create controlled friction conditions. It is used, for example, in a car brake.

Substantially a solid lubricant can be added, for example, "manually" to the relevant area to be lubricated. The disadvantage of this method is that it will require "relubrication" from time to time. In other words it has proven to be necessary, for example, to supplement the solid lubricant that is carried away (for example via a wear process).

At the same time, an idea was established to use solid lubricants as an essential component of the material mixture. In this case, the relevant solid lubricant is added to the actual material as a small particle-containing admixture (eg Metal material). In this case, autonomous lubrication is achieved by the wear of the relevant material due to wear. Devices constructed with such materials generally have an extremely high life, are particularly suitable for use in applications that are relatively difficult to access (problems for maintenance operations), and/or those that have relatively high wear, for example based on large dominant forces. .

One of the examples is a metal material with a solid lubricant as described in German laid-open patent application DE 1 533 222 A1. A suitable method has also been found to make such materials. The method proposed therein is a so-called sintering method in which different starting materials in the form of powder are mixed with each other and heated in the oven for a long time. The actual sintering process (heating in the oven) in the sintering process proposed in DE 1 533 222 A1 is carried out under standard atmosphere, optionally also in a protective atmosphere, but at standard atmospheric pressure. As a result, the resulting material generally has residual porosity that cannot be ignored. This results in a decrease in the strength of the resulting material.

European Patent No. EP 1 070 109 B1 discloses a novel solid lubricant and a brake formulation containing a solid lubricant produced using the solid lubricant proposed therein. It is also proposed to manufacture a solid lubricant by a sintering method. It is recommended to expose the metallic zinc and sulfur and carbon in a finely-distributed form to an inert gas atmosphere or air atmosphere at a temperature of from 200 ° C to 1500 ° C for a period of from 0.1 to 6 hours. The sintering process here is also carried out under standard atmospheric pressure. This therefore also produces materials with residual porosity that cannot be ignored.

A method of manufacturing a layer of hard material, and a product of laminating such a hard material, is proposed in the European patent application EP 1 652 608 A1. Wherein a material having a relatively high coefficient of expansion, for example Steel, on the entire surface of the object formed (where the surface can also have a fine area like a sharp corner), a layer containing the hard material is applied by hot-isostatic pressing. In order to prevent spalling, cracking, etc., particularly in critical areas, carbides and/or borides are used as hard materials because they have an expansion coefficient of at least 6.

A sliding contact structure having a first member and a second member is proposed in the Japanese Laid-Open Patent Application No. 2008-298258 A1, wherein one member is kept slidable relative to the other member. Wherein the first element comprises 5 to 40% by volume of solid lubricant particles and 5 to 40% by volume of hard particles in the metal substrate constituting the matrix. The second element contains 5 to 50% by volume of boron nitride particles in a matrix using tantalum nitride as a substrate. For the manufacture of components, different alternative thermoforming methods are recommended, such as hot pressing (thermal pressure sintering, etc.) or hot extrusion. In addition, other alternative methods are also proposed, such as press molding the composite powder (uniaxial pressing, cold pressure forming, etc.), followed by sintering or vacuum sintering the pressed powder under normal pressure.

Residual porosity is undesirable in particular when applied with large forces and/or accompanying large wear of the associated surface. Tests have shown that, in particular, residual porosity in the material can result in increased wear due to the range of fractured bearing surfaces, which of course is undesirable. In addition, pores can cause hygiene problems. This is a serious problem in some cases, especially in the field of food engineering and in the medical field.

There is therefore a need for self-lubricating materials having enhanced material properties relative to self-lubricating materials known in the prior art. In particular, it is desirable that the self-lubricating material produced has a particularly high strength and longevity. In addition, the self-lubricating materials produced should be as hygienic as possible.

The invention proposed in this case solves this problem.

The present invention proposes a method for producing a self-wetting composite material in which a main material (which is preferably present as a powdery hard metal material) is mixed with a secondary material (which is present in a powdery material relative to a soft material of the main material), and The mixture is subjected to a thermal pressure equalization method which is carried out in the following manner: the hot equalization method is carried out in a molding die in which the molding die filled with the material mixture to be hot-pressed is evacuated before the heat equalization method And the material mixture is pressurized in the molding die during the hot grading process to produce a target material that is at least substantially compact. The self-lubricating properties of the material (composite) are achieved in particular by having the resulting material ("target material"; composite material) have a proportion of at least one type of lubricant, in particular at least one type of solid lubricant. Therefore, in addition to "self-lubricating (composite) materials", it can also be called "lubricant-containing (composite) materials", especially "complex materials containing solid lubricants". The main material (as already mentioned) is in particular a metallic material provided in powder form. It is especially a hard material. Here, not only "pure metal" (such as iron) but also a mixture of metal materials (such as an alloy) is thought of. Purely by way of example, various types of steel and/or any form of commercially available hard material mixture are contemplated herein. "Hard" can think of HRC in particular 50. 51. 52. 53, 54, 55. 56. 57. 58, 59. 60. 61. 62. 63. 64. 65. 66 or Hardness of 67 (HRC stands for so-called Rockwell hardness). Especially in hardness In the case of 60, it is generally called a wear-resistant special alloy. (Other limits can also be used, especially the values mentioned above.) Soft secondary materials are also present in powder form. "Soft" is basically understood to be any combination of hardness. It may be particularly the case where, for example, "standard hardness steel" (as a soft secondary material) is mixed with a high hardness steel or other high hardness special alloy (as a main material). It is important that the hardness of the secondary material is lower than the hardness of the primary material (wherein the hardness difference of the HRC grade of, for example, 2, 3, 4, 5, 6, 7, 8, 9, or 10 (and above) should be sufficient) . It has proven to be preferable to use a solid lubricant (e.g., graphite or the like) known in the art of "conventional" as a secondary material. The powder provided can have substantially any shape (e.g., having spherical, irregular, angular, broken or deformed powder particles). The powder can also be produced by any method known in the art, such as, in particular, by atomization, atomization of materials, granulation or mechanical chip evacuation. The powder used therein can be made in the same manner and/or has a similar shape. Different manufacturing methods and/or shapes can also be used. This can be not only the ratio of primary material to secondary material. The powder of the primary material or the powder of the secondary material may also be a mixture of powders having different shapes and/or powders produced in different ways. The powders which are mixed with one another, in which substantially any mixing method known in the art can be used, are subsequently subjected to a thermal pressure equalization process. The hot grading method is carried out in such a manner that heat equalization is carried out in the forming mold (further method steps are required as needed). Wherein "heat equalization" means that the pressurization process is carried out under pressure on the one hand and usually at a high temperature. In addition, the thermal grading method can be performed in several "time periods". It has been confirmed that if only one "time period" of the actual heat equalization method is recommended, it is recommended to pressurize (and usually at a high temperature). Preferably, the "time as large as possible" ratio in the hot grading process (preferably substantially the entire pressurization process) is as recommended. With the aid of the forming die, the target material may have been "roughly" present in the final desired shape. In this way, the subsequent material processing can be reduced (especially, the post-processing time can be shortened). In addition, it reduces the amount of “waste” in the subsequent material processing (especially during the processing of the material being ground). Of course, it may also be necessary to use a small amount of powder mixture (especially to reduce the cost). By reducing post-processing requirements, the workpiece can be exposed to lower levels of vibration over time (which typically occurs during post-processing), which in turn can increase life. For the sake of completeness, it should be pointed out that by means of the forming die it is possible to carry out the shaping without depending on the shape of the workpiece to be realized. In this respect, "standard shape" is conceived herein, in particular, for example, a rod shape, a rectangular parallelepiped shape, a cubic shape, a cylindrical shape, and the like. As already mentioned, the thermal pressure equalization process is carried out by heat-equalizing a forming mold filled with a material mixture to be pressurized, usually a mixture of at least one main material and a secondary material. Vacuum is applied before the "actual pressurization process" in the law. This is generally done after the powder has been filled into the forming die. It is also possible to add "multiple" powder. The powder can be filled with a vacuum followed by a new batch of powder, then vacuumed and the like. By means of the proposed vacuuming, it is possible on the one hand to reduce possible voids and/or reduce the number of holes before the actual heat equalization process. In addition, the (residual) amount of gas (air atmosphere and/or shielding gas) can also be reduced. It is known that such "remaining gas amount" will react with the surface of the powder particles, which may cause deterioration of the material properties of the target material (i.e., the composite material to be produced). Surprisingly, even a relatively poor vacuum has been sufficient to substantially increase the material properties of the target material. Especially thinking about stress 200 mbar, 150 mbar, 100 mbar, 75 mbar, 50 mbar, 25 mbar, 10 mbar, 5 mbar, 2.5 mbar, 1 mbar, 0.5 mbar, 0.25 mbar or A vacuum of 0.1 mbar. The vacuum provided therein can be chosen entirely depending on the nature of the material desired. It has been confirmed that it is also useful if the "lower vacuum" is not a vacuum, but the opposite residual specific (especially protective gas) minimum pressure is also useful. As a suitable minimum value, the value already mentioned above (previously referred to as the upper limit value) can be used. Combinations of "lower limit" and "upper limit" are also conceivable. In addition, if the molding die filled with the starting material is a (vacuum-tightly) sealable mold, it is then evacuated and closed (vacuum-tightly) so that it can be used "in a simple manner independently". And the delivery system is preferred. It is particularly preferred that such a (vacuum-tightly) sealable mold allows the actual oven cavity to be subjected to a thermal pressure equalization process at (substantially) any pressure. The hot press method material mixture is pressurized in a molding die. Especially thinking 200bar, 300bar, 400bar, 500bar, 600bar, 700bar, 800bar, 900bar, 1000bar, 1100bar, 1200bar, 1300bar 1400bar, 1500bar, 1600bar, 1700bar, 1800bar, 1900bar or Pressure of 2000 bar. The volume and/or amount of cavities in the material mixture to be pressurized/pressurized can be reduced by pressurization. If the pressurization is combined with a vacuum forming (and optionally deformable) mold that is hermetically sealed by vacuum, the material mixture does not "directly" reach the gas pressure, especially in an oven (autoclave), which usually has great advantages. . If it is mentioned herein that the molding die filled with the material mixture to be hot-pressed is vacuumed before the hot equalization method, and the material mixture is formed in the molding die (usually mechanical and/or external) during the thermal pressure equalization process. The inside is pressurized, which usually also means that the vacuum is still present/held while being pressurized. "External" pressurization is generally understood to be the action ("production") acting outside the forming mold, and the pressurization (urging force) acting on the material mixture located in the forming mold. The vacuum may be the same (substantially) the same as when the molding die is filled with a mixture of materials. However, it is conceivable that the vacuum will increase (become better; lower residual pressure) or decrease (deterioration; higher residual pressure) after filling the molding die with the material mixture. Additionally or alternatively, (partial) "gas exchange" is also contemplated, for example by rinsing with a shielding gas or the like (especially as described in the context). In other words, the forming mold filled with the material mixture to be hot-pressed can be evacuated before the heat equalizing method, and the material mixture is substantially maintained in the forming mold during the heat equalizing method (or as needed The vacuum is applied (mechanical and/or external) according to the pressure level or the gas composition "change". Or it can be said that the molding die filled with the material mixture to be hot-pressed is evacuated (becomes vacuum, vacuum, etc.) during at least part of the heat equalization method, and the material mixture is allowed to be in the process of the thermal pressure equalization method. Pressurization in the forming mold (regardless of at least temporary/partial residual/presence/generated vacuum). Of course, the pressurization is of course not "continuously by applying air pressure" / by "pressurizing directly with gas" (however, this does not preclude indirect use of air pressure to pressurize, for example, by passing through a sintered mold wall formed into a flexible shape). It is of course conceivable that the vacuum press is only present in a part of the pressurization, in particular the temporary part. It is also conceivable, in addition or alternatively, to change the vacuum (pressure, gas composition, etc.) during pressurization. In order to explain again the idea: in the existing sintering process in the art, the material mixture to be sintered is pressurized, in particular in the filling phase and/or in the heating phase, at a different pressure (and/or gas composition) than the standard atmosphere. For example, it is recommended to fill the sintered mold under reduced pressure to avoid the formation of "balloons". There is basically also the idea of vacuum sintering or sintering in a protective gas atmosphere. However, here (unlike the proposed method) no (mechanical and/or external) pressure acts on the material mixture during the heating phase. Conversely, sintering also applies pressure to the material mixture during the (most) heating phase (for example by treatment in an autoclave). However, the material mixture is not under vacuum (or is not at a different pressure than the surrounding atmosphere). The compacted target material (the final product or intermediate product of the entire production process) can be obtained by a hot press method under the vacuum "on a vacuum (based on a mixture of materials to be pressurized/pressurized). It is different from the target material produced by the sintering method in the prior art, and has no (or at most small) residual pores. This "goal" seems unreasonable because it seems strange to carry out a relatively expensive thermal grading method (which is basically a "special sintering method") in order to obtain a compacted target material (composite material). . This is because it has been assumed to date that it is easier to manufacture compacted target materials by other manufacturing methods, and/or the sintering method has the advantage of being able to produce particularly porous materials. However, the inventors have found that surprisingly excellent material properties (composite properties) can be achieved by means of the proposed method, which makes the relatively expensive manufacturing method using the thermal grading method seem unreasonable. In particular, the material (composite material) which can be produced by this method has a particularly high strength and has self-lubricating properties. Relative to "traditional materials" (especially "conventional sintered materials" and "traditional hot-pressed materials"), the tendency to wear, especially due to the tendency of fracture wear, can be partially reduced significantly. In addition, a hygienic material (composite material) can be achieved by means of the proposed method, which is particularly important in the food sector and/or in the medical field.

Special recommendation with target material 2.5%, 2%, 1.5%, 1%, 0.5%, 0.25%, 0.2%, 0.1%, 0.05% or The method of the present invention is carried out in a manner of a porosity of 0.025%. Alternatively or additionally, the target material may have a higher density than the starting material having a lower density, preferably higher than the weighted average density of the starting material, in particular higher than the starting material having a higher density. Starting materials are understood in particular to be primary and secondary materials (additional blends, such as ceramic powders, binders, etc., if desired). It is specifically noted herein that in the proposed method it is actually possible to even increase the density of the starting material relative to (unpowdered). Obviously, it is thereby possible to realize a material having an extra long life.

It is particularly recommended to carry out the method of the present invention by using a molding die which is deformed under pressure as a molding die. If the forming die can be deformed under pressure, the mold may be particularly susceptible to changing volume ratios (e.g., expansion effects, particularly in the shrinking process common to thermal pressure equalization) when performing the process of the present invention. It may also be the pressure that acts on the material "through the mold", especially the pressure of the fluid. As a deformed molding die, it is suitable, for example, as a thin-walled metal mold (a can-shaped container, which is generally provided with a filling opening; wherein the filling opening is preferably mechanically, in particular still fluid-tight; in particular in a closed mold A "squeezing" of a tubular implementation is conceivable, in which the fusion can be effected, for example, by applying a strong current pulse to the pressing zone.

It is particularly preferred to carry out the process of the invention by means of a pressurization by means of a fluid. Such pressurization can be carried out, for example, by processing in an autoclave, which is generally at a high pressure (or fluid pressure) in its internal space. In particular, the pressure of the fluid that has been mentioned above is considered.

It is further proposed to carry out the process of the invention in such a way that the lowest proportion of the main material is 45 weight percent and the highest proportion is 99 weight percent. The first test showed that (target) materials with exceptional properties were produced in this interval. On the one hand, a particularly strong material can be achieved with a lower limit. The first test showed that too high a volume ratio or weight ratio of "additives" (especially solid lubricants) would cause chipping in the components and, in addition, reduce proper diffusion between the powder particles. On the other hand, the upper limit usually ensures sufficient lubricating properties of the (composite) material produced. Of course, other ratios can be thought of. In particular, the lower limit as the main material may be 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95% by weight. In a similar manner, the maximum ratio is expected to be 80, 85, 90, 95, 96, 97, 98 or 98.5 weight percent as an upper limit. Feasible additives (eg, binders) can be "vested" in either or both of the primary or secondary materials (and, if necessary, the ratio of the materials to each other).

The first experiment has confirmed that it is preferred to use at least one material selected from the group consisting of M390, ASP 60, X260, HIP65-WC, Stellite 12, tungsten carbide, or the like in the method of the present invention. Iron, iron alloy, steel, cobalt, cobalt alloy, nickel and nickel alloy. Such materials generally have sufficient hardness and are therefore particularly suitable for mixing with secondary materials (solid lubricants) to achieve particularly good target materials. The material is a particularly wear-resistant metal or special alloy available on the market. In the case of tungsten carbide (WC), it is usually present as a stoichiometrically fixed mixture of 93.9 weight percent tungsten and 6.13 weight percent carbon. But it may change this ratio by over-sintering and release it Free carbon. However, this causes the tungsten carbide to be deficient in carbon and thus the brittleness. But this can be prevented by increasing the proportion of binder, for example by the ratio of cobalt or nickel. Another possibility is to add extra carbon to the system so that the stoichiometric ratio does not change. Free carbon in the presence of graphite acts as a solid lubricant and reduces wear.

It is advantageous when the method of the present invention uses a material having a solid lubricant (solid lubricant) or a material which is itself a solid lubricant (solid lubricant) as a secondary material. This material is particularly suitable in combination with the method proposed by the present invention (especially for the heat equalization step). In addition, such lubricants are often particularly preferred when used because they are, for example, less washed away from the "use position" (relative to the liquid lubricant). Solid-state lubricants can basically use any solid-like lubricant/solid lubricant known in the art. However, it is also possible to use, for example, a "package fluid" such that the lubricant "bes first solid" but is present as a fluid after leaving the capsule shell.

In particular, it has been confirmed that it is preferred to use at least one material selected from the group consisting of GJSA-XNiSiCr 35-5-2, X120Mn12, X2NiCoMo1895, x53CrMnMoVNb2-9 in the method of the present invention. , X2NiCoMo1895, Nitronic 60, graphite, boron nitride, molybdenum disulfide, graphite sulfide, tungsten sulfide, talc and mica. Such materials are solid lubricants known in the art. However, it is possible to produce a particularly good effect in combination with the proposed method and in particular in combination with the above-mentioned main materials.

It should be noted separately for completeness, of course other major materials and/or other secondary materials may also be used.

Preferably, the powder particle size is at least one starting material (preferably two or all starting materials) 0.001mm and / or The method of the present invention is carried out in a 1 mm manner. Other values are of course conceivable as upper and/or lower limits, for example in particular 0.002 mm, 0.005 mm, 0.01 mm, 0.02 mm, 0.05 mm, 0.1 mm, 0.2 mm and/or 0.5 mm. Such powders can be produced by atomization in a relatively simple, low-wearing manner and in sufficient quantities (and using commercial machinery).

Another preferred development of the process of the invention can be produced when the hot grading process is carried out at a temperature below the melting temperature of the lower melting starting material and/or during a period between 1 and 12 hours. The temperature is preferably selected by multiplying the melting point of the starting material of the lower melting point by the temperature calculated by the specific coefficient. It is particularly preferable to select a temperature range of 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, 0.97 or 0.98 times the melting temperature of the product having the lowest melting point (wherein the above value can be used as the lower limit or the upper limit). Among them, the solidus temperature and the liquidus temperature can be used as the melting point. It is also possible to select an additional time limit for the actual heat equalization time. Purely by way of example, 0.25, 0.5, 1, 2, 5, 10, 15, 20 or 24 hours may be selected as the lower or upper limit.

If at least a portion of the particles (powder particles) of the secondary material, in particular at least a portion of the solid lubricant particles, are provided with a diffusion barrier layer in the process of the invention, another advantage may be created wherein the diffusion barrier layer is preferably nickel, Cobalt, tungsten or molybdenum. In particular, the diffusion prevention refers to the degree of diffusion relative to the lubricant (solid lubricant) used. Thereby, the resulting composite material can be produced with a particularly long shelf life/storage life without significantly reducing the lubricating properties in (subsequent) use. Especially in To some extent, the relevant lubricant can be directly released to the immediate "friction position" by the "friction process". Prior to this, it is possible to "extra" the lubricant in the material composite and, for example, not "exhaust" or the like. Non-diffusion may additionally or alternatively be associated with, for example, oxygen in the air (or other unfavorable materials/substances, in particular materials/substances that should be treated, for example, in a mixer or kneader). The associated lubricants herein can be protected from contact with the relevant materials/related substances so that their adverse degradation can be prevented before "actual lubrication".

It is further proposed to use a composite material which can be produced by the above, or which is produced by the above method. Composite materials can have the same properties and advantages in at least a similar manner. Of course, composite materials can be further developed, especially in light of the above.

It is preferred to use such a composite material as a self-lubricating (composite) material and/or in a bearing region of a mechanical device. In this case, the composite material can satisfy its inherent properties in a particularly good manner.

Finally, a mechanical device is proposed which has a composite of the type suggested above, at least in part. This composite material can be used in particular for at least one bearing region of a mechanical device. Such mechanical devices can also have the aforementioned properties and advantages in at least similar manner. Furthermore, the mechanical device can be further developed at least in a similar manner as described above. It is particularly conceivable to form part of the mechanical device (for example a housing or a worm shaft) in sections, wherein the sections are made of different materials (or have different materials) and/or the sections are designed to be exchanged independently.

It has proven to be particularly advantageous for the mechanical device to have a shaft and/or a housing housing, in particular a worm shaft and/or a worm shaft seat. The housing, and preferably has an extrusion device, or the mechanical device is constructed as an extrusion device. Particularly in these technical applications, the self-lubricating bearing region of the mechanical device, which can be realized in a preferred manner by means of the proposed composite material, can prove to be particularly preferred. Further, it does not matter whether it is a single-screw kneader, a twin-screw kneader or a multi-screw kneader.

Furthermore, it is particularly preferred for the mechanical device to be constructed on the outside of the bearing region, which generally consists of or has such a composite material as the proposed self-wetting composite material, in particular in accordance with a method different from the method described above. The material formed. In particular, it can be "traditional materials", especially "traditional sintered materials". Purely by way of example, general steel or wear resistant special alloys can be used in this field. This generally allows the cost of the entire unit to be significantly reduced without having to give up the advantages of self-lubricating bearings.

In particular, it can be confirmed in the following description that it is preferable that "other standard components" (for example, the mixing blades on the shaft and/or the kneading pins along the shaft housing) have a gap which may be relatively significant with respect to the bearing region (up to a few millimeters). In this way, the bearing area will "wear" for a certain period of time before any areas of the device may also be affected by mutual contact. As the "relative gap", a gap of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 7.5 mm, or 10 mm (upper or lower limit) can be particularly considered.

1‧‧‧ autoclave

2‧‧‧HIP mold

3‧‧‧ powder mixture

4‧‧‧Cylindrical notch

5‧‧‧ Filling port

6‧‧‧Squeeze zone

7‧‧‧Internal space

8‧‧‧Compressor

9‧‧‧Shell

10‧‧‧ worm shaft

11‧‧‧Drive shaft

12‧‧‧ Filling port

13‧‧‧Outlet

14‧‧‧ bearing area

15‧‧‧"General Mixed Blades"

16‧‧‧"General Kneading Pin"

17‧‧‧Bearing area - mixing blades

18‧‧‧ bearing bushing

19‧‧‧ worm components with hybrid blades 15

20‧‧‧ worm components with hybrid blades 17

21‧‧‧ Flowchart

22‧‧‧Smashing process

23‧‧‧Mixed process

24‧‧‧Adding HIP mould

25‧‧‧ Vacuum process

26‧‧‧Back arrow

27‧‧‧ airtight seal

28‧‧‧ HIP method steps

29‧‧‧Cooling step

30‧‧‧Remove composite materials

Further details of the present invention and specific embodiments of the proposed apparatus and the proposed method will be described below with reference to the accompanying drawings. Has been shown: 1 is a schematic view of a part forming mold of a filled powder mixture in an autoclave; FIG. 2 is a schematic sectional view of a worm extruder having two bearing areas; and FIG. 3 is a feasible manufacturing method of a self-lubricating composite material Schematic flow chart.

Fig. 1 shows how the HIP mold 2 filled with a suitable powder mixture 3 ("HIP" means "heat grading"; a sintering mold) how the actual HIP pressing process of the powder mixture 3 is carried out in the autoclave 1. The HIP mold 2 is designed from its outer shape to allow the workpiece produced by the HIP-pressed target material (starting from the powder mixture 3) (in the process, there may also be an "intermediate stage", ie a blank) A certain degree of "oversized" expected shape. This allows the resulting workpiece to reach its final shape at a relatively low cost. In particular it is possible (in the case of a grinding process) to cut off with a relatively small amount of material sufficient to produce the final workpiece (for example by turning, grinding, etc.). It is advantageous to mold by the HIP mold 2 which is somewhat oversized in that the HIP method often cannot avoid a certain degree of dimensional tolerance. By some extent, it is usually too large to reduce the defective parts of the workpiece (especially those that are excessively shrunk and therefore can no longer be formed into a desired shape by the molding of the abrasive material), and (obviously) It is beneficial. In addition to reducing the post-treatment process, it has the further advantage that less powder mixture 3 is required, which also leads to cost reduction.

In the embodiment shown in Figure 1, the HIp mold 2 has a cylindrical indentation 4 which forms a blind hole in the final workpiece.

The HIP mold 2 is filled with the powder mixture 3 through a closable filling opening 5. After filling the HIP mold 2 with the powder mixture 3, the HIP mold 2 is evacuated (absorbed air) and hermetically sealed by the pressing zone 6. The squeezing zone is for example realized by the tubular workpiece being moved towards each other by means of two tool parts. Preferably, it can be a welding rod and a welding sonotrode. In this case, it is possible to achieve "additional closure" by "setting the solder joint" (for example, by applying a short, strong current pulse between the electrode and the welding anvil) after the extrusion process. A long-lasting (vacuum-tight) fluid seal (at least during the period corresponding to the HIP method).

The HIP mold made in this way achieves the desired density in the HIP device.

The so-called co-extrusion machine 8 is shown in a schematic cross section in Fig. 2. Typically, the coextrusion machine 8 typically has a housing 9 and an internal worm shaft 10. In the co-extrusion machine 8, the worm shaft 10 not only rotates but also linearly moves in the longitudinal direction of the worm shaft 10 (or the casing 9), which is indicated by a corresponding arrow in Fig. 2 . The drive train is completed by a drive shaft 11 that passes through the housing 9 (from the left side in Fig. 2) from one side. On the side provided with the drive shaft 11 there is a housing 9 and a filling opening 12 through which the material to be mixed is introduced (which is also of the type provided with a plurality of filling openings 12, part of which is also along the housing The length of 9 is formed). On the side of the housing 9 corresponding to the drive shaft 11, an output port 13 is provided in the housing 9. In order to prevent the output of the mixed material from being blocked when passing through the output port 13, it is preferable to "end" the worm shaft 10 before the output port 13, so there is no part. The minute worm shaft 10 extends through this side of the housing 9 or is adjacent to the output port 13. Sometimes based on the considerable length of the coextrusion machine 8 (generally 1 m to 5 m in length) and the forces encountered in the particular material, most of the inevitable bearings are provided at least at a point spaced apart from the drive shaft 11 in the housing 9. A region 14 in which the worm shaft 10 is supported. However, a plurality of bearing zones 14 are usually provided. In the above embodiment, two bearing regions 14 are provided.

Also common in the co-extrusion machine 8, a plurality of worm elements 19, 20 with mixing blades 15, 17 are provided along the worm shaft 10, and a plurality of kneading pins 16 are provided along the inner side of the housing 9, the kneading pins It is used to fully mix the materials to be mixed.

In order to achieve the longest possible service life of the co-extrusion machine 8 while achieving a reasonable cost, the invention proposes a worm element 19 and a housing outside the bearing region 14 with a mixing blade 15 ("general mixing blade"). The size of the worm element 19 with the mixing blade 15 (of the worm shaft 10) and the kneading pin 16 (of the housing 9) is determined by the presence of a gap between the nines. In this case, for example, a gap of 3 mm is provided. Further materials are used in this range, such as high hardness steels (which are commercially available and inexpensive).

In contrast, in the bearing region 14, the worm element 20 with the mixing blade 17 ("protruding mixing blade") of the worm shaft 10 is frictionally contacted with the corresponding bearing region 14 of the housing 9 The way to determine the size.

The present invention suggests the use of a self-lubricating composite material in the bearing region 14. In this case, by making a partial region (for example, a segment) of the casing 9 in the bearing region 14 with the self-wetting composite material. Now. The same applies to the worm shaft 10. It is further preferred that the corresponding component/component regions (the worm element 20 with the mixing blades 17, the region of the worm shaft 10 and/or the region of the housing 9) (each independently) are designed to be interchangeable.

By the frictional contact between the mixing vanes 17 and the casing 9 in the region of the bearing region 14, a permanent lubrication is achieved in the bearing region 14 based on the special properties of the self-lubricating composite. In addition, the long service life of the co-extrusion machine 8 is achieved based on the high hardness still existing in the self-wetting composite material.

In the unavoidable bearing area 14 during operation, wear is encountered in the range in which the housing 9 and the worm element 20 with the mixing blades 17 are in contact with each other. However, based on the "standard mixing blade 15", the distance between the housings 9 or the "pinch pin 16" is long enough for the worm shaft 10 to be non-detrimental (ie, the housing 9 and the belt are not encountered outside the bearing region 14). The worm element 19 of the mixing blade 15 is in continuous contact until the "wear limit range" is exhausted (i.e., the wear progression in the bearing region 14 substantially conforms to the original design void outside the bearing region 14).

Maintenance of the co-extrusion machine 8 can be performed before this occurs. Normally, the associated worm element 20 of the worm shaft 10 can be replaced with the bearing region 14 of the housing 9. Such a replacement of the "entire device" of the co-extrusion machine 8 is relatively inexpensive. Next, the co-extrusion machine 8 can pass a new "wear cycle".

It should be noted that the "standard" mixing blade 15 and the housing 9 of the worm shaft 10 will not be encountered at all times outside the bearing region 14 when the co-extrusion machine 8 is properly selected for operation (e.g., in accordance with a specified maintenance cycle). Contact. There will also be no encounter with the pinch pin 16 and the worm shaft at any time. 10 contacts. However, the outer mixing blade 15 and the kneading pin 16 in the bearing region 14 still experience some degree of wear due to friction with the material to be mixed. However, this wear is relatively small, so that the worm element 19 with the "standard" mixing blade 15 and the replacement of the kneading pin 16 must be replaced before the usual "wear cycle" is performed.

A schematic flow chart 21 of a possible manufacturing method for a self-lubricating composite is shown in FIG. In a first step 22, the starting material, in particular the primary material and the secondary material, are comminuted or atomized from the melt to be present in powder form. In the next step, the starting materials which are now present in powder form are mixed with each other 23 . The powder mixture presently present is added to the HIP mold in a further step 24. The HIP mold is evacuated in a subsequent step 25, i.e., a negative pressure is applied.

The step 24 of adding the powder mixture to the HIP mold and the vacuuming treatment step 25, which are indicated by the return arrow 26, can be repeated as needed.

The HIP mold is then hermetically sealed 27 and then exposed to high pressure and elevated temperature, for example, in an autoclave. This is the actual HIP processing step 28.

The resulting composite is taken out of the mold 30 after the cooling step 29. This can be done, for example, by destroying the mold (the so-called "disappearing mode").

The resulting artifacts can be re-processed (not separately listed here).

Further description of the self-wetting composite material proposed by the present invention will now be further described below with some exemplary material combinations.

[References]

In order to be able to compare, first of all, in order to have the pressure, speed, quantity, and the fixed precision of the housing and the worm and worm extruder with each equal scale ratio, a combination of materials common in the art is selected. The combination of materials listed in Table 1 is used at this time. The physical and mechanical properties of these materials are listed in Table 2, and the composition of the relevant materials is shown in Table 3.

Specifically mentioned in Table 3, tungsten carbide (WC) with nickel and supplemental carbon (Ni+C) is listed. Tungsten carbide is typically composed of 93.9 weight percent tungsten and 6.13 weight percent carbon and is fully stoichiometrically fixed. By over-sintering this ratio can be changed and free carbon released. But now tungsten carbide lacks carbon and the brittleness increases. This can be prevented by increasing the binder ratio, such as by adding cobalt or nickel. Another possibility is to add extra carbon to the system and thereby keep the stoichiometry constant. Since then, the freely present carbon of graphite functions as a solid lubricant (solid lubricant) and reduces wear.

[Example of proposed lubricant-containing composite material]

Fourteen reference tests were performed in the first test phase, with the combination of materials, particle size and mass ratio (or volume ratio) used, as well as the mixing times used separately, as provided in Table 4 attached. The density of each of the materials used is also listed in the accompanying Table 5.

The starting materials, each in powder form, in all of the examples carried out were mixed with each other for 1 hour in a Turbula mixer. The powder mixture thus obtained was filled in a steel capsule, evacuated and then sealed. The capsules were then hot pressed to a density of 100%, tested and machined to the desired shape. For all combinations of materials used, wear is reduced compared to the measured wear behavior (see above). The heat equalization process was carried out for 3 hours at a pressure greater than 400 bar. The HIP method temperature ("sintering temperature") is the solidus temperature of the material having the lowest melting point of the material used for 0.8 x T _Solidus .

According to a further preliminary test, it is also advantageous to use a plurality of blends other than the substrate (main material) instead of a single mixed material (secondary material). The first test was carried out in the combination of the materials listed in Table 6.

It seems to be useful in selecting the mixing ratio as follows: substrate = 45 to 95 weight percent and metal blend = 5 to 55 weight percent (in the case of metal blends), or substrate = 70 to 99 weight percent Divided and solid lubricant = 1 to 30 weight percent (in the case of solid lubricants). Tests have shown that, especially in the case of solid lubricants, the volume ratio is set at a maximum of 60% because solid lubricants have a lower density. Otherwise a lower density will cause breakage in the component and further proper diffusion between the powder particles may be hindered.

1‧‧‧ autoclave

2‧‧‧HIP mold

3‧‧‧ powder mixture

4‧‧‧Cylindrical notch

5‧‧‧ Filling port

6‧‧‧Squeeze zone

7‧‧‧Internal space

Claims (15)

A method for producing a self-wetting composite material (21), wherein a main material preferably present in a powdery hard metal material is mixed with a secondary material present in a powdery material relatively soft relative to the main material, and The mixture (3) is subjected to a thermal pressure equalization method (28), characterized in that the thermal pressure equalization method (28) is carried out in a molding die (2), wherein the material mixture (3) to be subjected to heat equalization is filled. The molding die (2) is evacuated (25) before the hot grading method (28), and the material mixture is pressurized in the molding die (2) during the thermal grading process to produce at least substantial Upper compacted target material. The method (21) of claim 1, wherein the target material has 2.5%, 2%, 1.5%, 1%, 0.5%, 0.25%, 0.2%, 0.1%, 0.05% or a porosity of 0.025%, and/or a density higher than the starting material having a lower density, preferably higher than the weighted average density of the starting material, especially higher than the density of the starting material having a higher density. . The method (21) of claim 1 or 2, wherein the molding die (2) which is deformed under pressure is used as the molding die (2). The method (21) according to any one of the preceding claims, wherein the pressurization is carried out by a liquid. A method (21) according to any one of the preceding claims, wherein the primary material is present in a ratio of the lowest ratio of 45 weight percent to the highest ratio of 99 weight percent. A method (21) according to any one of the preceding claims, wherein at least one material selected from the group consisting of: M390, ASP 60, X 260, HIP65-WC, Stellite 12, tungsten carbide, iron, iron alloy, steel, cobalt, cobalt alloy, nickel and nickel alloy. The method (21) according to any one of the preceding claims, wherein a material having a solid lubricant or a solid lubricant is used as a secondary material. A method (21) according to any one of the preceding claims, wherein at least one material selected from the group consisting of GJSA-XNiSiCr 35-5-2, X120Mn12, X2NiCoMo1895, X53CrMnMoVNb2-9, X2NiCoMo1895, Nitronic 60, graphite, boron nitride, molybdenum disulfide, graphite sulfide, tungsten sulfide, talc and mica. A method (21) according to any one of the preceding claims, wherein the powder particle size of at least one of the starting materials is 0.001mm and / or 1mm. The method (21) according to any one of the preceding claims, wherein the heat equalization method (28) is carried out at a temperature lower than a melting temperature of the lower melting point starting material, and/or is carried out at a ratio of 1 to 12 hours period. The method of any one of the preceding claims, wherein the particle of at least a portion of the secondary material, in particular at least a portion of the solid lubricant particle system, is provided with an anti- The diffusion layer, wherein the diffusion prevention layer preferably has nickel, cobalt, tungsten, and/or molybdenum. A composite material, which can be produced by the method of any of the above claims, and/or by the method (21) of any of the above claims. A use of the composite material of claim 12 for use as a self-lubricating material and/or in a bearing region (14) for use in a mechanical device (8). A mechanical device (8), characterized in that it has a composite material as claimed in claim 12 at least in a partial region, in particular a composite material as claimed in claim 12 at least in the bearing region (14). The mechanical device (8) of claim 14, wherein the mechanical device (8) has a shaft (10, 11) and/or a shaft housing (9), in particular a worm shaft (10) and/or a worm shaft housing The housing (9), preferably having an extrusion device (8) or a mechanical device (8), is constructed as an extrusion device.