KR20170068429A - Anti-galling method for treating materials - Google Patents

Abstract

A galling suppression method for treating a material, comprising: a first preliminary heat treatment step for increasing the surface hardness of at least one of at least two elements connected to each other at least in one freedom and made of a metallic material; A preliminary surface grinding step is carried out, the method comprising the first step of cleaning at least one part of the surface of the at least one element which has been subjected to the preliminary step, and at least one of the surfaces of the at least one element And a third step of forming a molybdenum disulfide layer on at least one portion of the at least one element that has been previously subjected to the shot peening process is performed by performing a second step of performing a shot peening process on a portion of the molybdenum disulfide .

Description

ANTI-GALLING METHOD FOR TREATING MATERIALS "

The present invention relates to a method for inhibiting gingling to treat a material.

During normal operation, the two mechanical bodies that slide against each other may suffer a phenomenon called galling.

"Gulling " generally refers to the locking of two or more complementary moving mechanical members due to excessive sliding friction, which may result in temporary or permanent interruption of the periodic operation of the mechanical member due to excessive sliding friction have.

This gulling can occur for a variety of reasons, which can lead to one consequence, excessive overheating of the propulsion unit. For example, gauling can be caused by a lack of lubrication, excessive output at full power and extended overtime (e.g. caused by higher operating speeds than the machine's actual capability), or incorrect clearance between parts (An excessively small clearance between the bushing and each pivot can result, for example, in the interruption of the lubricant film, and excessive clearance can preclude accurate isolation of the lubricant and can also cause collisions between the elements).

While there are many mechanical couplings in which no lubricant is used, there is usually a lubricant between the reciprocating elements.

In principle, the present invention is preferably directed to a pivot-bushing assembly comprising a metallic material (e.g., steel, aluminum and other types of alloys) and reciprocating elements.

In this type of assembly, gulling often results in machine breakdown and significant damage to the pivot.

In order to avoid these disadvantages, lubricating oil is often interposed between the pivot and the bushing (within the gap between them) and isolated there by a specific sealing element.

In some cases, however, the lubricating oil may not be sufficient to avoid goring, especially after a number of operating hours.

Thus, especially in the known types of assemblies, galling occurs. Periodic maintenance is provided to check the condition of the lubricant at the clearance between the pivot and the bushing and to restore the ideal condition of the lubricant to avoid the occurrence of this gulling.

Therefore, frequent and expensive periodic maintenance of the assembly is required if a known type of assembly is to suffer from a golfering phenomenon and to avoid the occurrence of this phenomenon (which would cause machine downtime).

To reduce the occurrence of gulling, it is known to perform different kinds of heat treatments for pivots made of quenched and tempered steel, after which the surface of the pivot is ground.

Even after performing the above processing on the pivot, the pivot can under any circumstances be subjected to a golfer phenomenon, and thus the long service life of the pivot is not guaranteed.

The object of the present invention is to solve the above-mentioned problems by proposing a method of inhibiting the golfer to treat the material, which can minimize the occurrence of the golfer negligibly.

Within the scope of this goal, it is an object of the present invention to propose a method of inhibiting the golfer to treat the material, which minimizes the risk of pivoting of the rotating pivot relative to the mating bushing.

It is a further object of the present invention to propose a method of inhibiting goring to treat a material, which can reduce the periodic maintenance of the mechanical coupling, including the elements to which the method is applied.

Another object of the present invention is to propose a method of inhibiting the golfer to treat the material, which is inexpensive, relatively simple to provide in practice, and safe in application.

These and other objects which will become more apparent hereinafter will be attained by a galling suppression method for treating a material wherein at least two elements connected to each other at least in one freedom and made of a metallic material A first preliminary heat treatment step for increasing the surface hardness and a second preliminary surface grinding step are carried out,

- carrying out a first step of cleaning at least one part of the surface of the at least one element which has been subjected to the preliminary step,

Performing a second step of performing a shot peening process on said at least one portion of the surface of said at least one element that has been previously cleaned,

- a third step of forming a molybdenum disulfide layer on said at least one part of said at least one element which has been previously subjected to shot peening.

Other features and advantages of the present invention will become more apparent from a preferred but non-exclusive embodiment of a method for inhibiting gingling for treating a material according to the present invention, which is illustrated by way of non-limiting example in the accompanying drawings, Sectional view of a possible rotatable mechanical coupling provided by applying the method of inhibiting galling according to the present invention along a transverse plane.

Referring particularly to the drawings, reference numeral "1 " generally refers to a rotatable mechanical coupling that is provided by applying a gulling suppression method for processing materials according to the invention.

The method according to the invention can be applied to a mechanical coupling with at least one degree of freedom.

The element is preferably made of a metal material, for example, a metal alloy such as a steel, or a metal in a substantially pure state (e.g., aluminum). When referring to elements made of steel, quenched and tempered steels will generally be used.

In the method of inhibiting ghaling according to the present invention, a first preliminary heat treatment step and a second preliminary surface grinding step are carried out for at least one of the at least two elements to increase the surface hardness.

The two preliminary steps are usually the steps applied in the background art.

The method according to the invention carries out an additional continuous step for at least one element.

In fact, it is necessary to carry out a first step of cleaning at least one part of the surface of the at least one element which has been subjected to the preliminary step.

There is then a need to perform a second step of performing a shot peening process on said at least one portion of the surface of the at least one element that has been previously cleaned.

Finally, there is a need to perform a third step of forming a molybdenum disulfide layer on said at least one portion of at least one element that has been previously subjected to the shot peening process.

The cleaning step is also useful to include surface degreasing at least one portion of the surface of the at least one element that has been subjected to the preliminary step.

Degreasing consists in removing oil or dirt from the surface of the element (usually made of steel) before the next treatment (mechanical treatment, thermal treatment, etc.) or surface finishing. Since the presence of organic molecules (consisting essentially of carbon) can be dangerous, it is important to remove grease and dirt, so that when the heat treatment is carried out, the carbon can actually enter the matrix of material during the heat treatment The carbon contained in the oil present on the outer surface of the part to be processed can move even by some mechanical treatment), resulting in aesthetic damage to the part and also in the local deterioration of its properties. Carbonation can adversely affect the mechanical properties of the part due to curing and embrittlement, and even reduce the corrosion resistance of the part.

The degreasing may be carried out with an organic solvent using the chemical principle of "melting with each other" or with an alkaline or acidic solvent in an aqueous base. In this second case acts on the hydrophilic part of the compound;

A second step of performing a shot peening process on said at least one portion of the surface of said at least one element that has been previously washed continues until a residual compression state of 200 MPa to 10000 MPa is obtained in said at least one portion, The ideal value of the residual compression that can be obtained for the correct implementation of the method according to the invention is approximately 1100 MPa.

Shot peening consists of surface cold-hammering using a cylindrical shot (called a wire cut shot) obtained by cutting a violent jet or wire of a spherical shot.

The machine, i.e., the peening machine, which performs this process, directs the jets of the rounded or cylindrical shot to one or more rapidly rotating impellers, typically a centrifugal impeller, or compressed air toward the workpiece part, The materials used for grit are cast iron, steel, glass and, more rarely, ceramics.

Furthermore, shot peening improves the distribution of surface tension disrupted by mechanical treatment and / or heat treatment and also weakens the concentration of labor caused by notches, threads, decarburization, and the like.

In practice, shot peening is more like sanding because it acts more on plastic than on abrasion, which is more like rolling on purpose.

In fact, shot peening causes surface compression because its jets cause plastic deformation to propagate down to a depth of a few tenths of a millimeter in the material under consideration and technically improve the distribution of surface tension to increase the fatigue strength of the treated portion Because it plays a role.

This effect is due to the residual compressive tension induced in the surface of the material and in the underlying layer, which can reduce the internal tensile when the part is stressed. Therefore, the material becomes more resistant to fatigue stress.

At the end of the treatment, as a side effect, the amount of light reflected from the material is also reduced (i. E., A kind of polished finish), due to the micropores that are generated and superimposed on one another.

If the characteristics of the shot peened material are constant, the effect of shot peening depends on the hardness and size of the shot, the flow rate, the speed and impact angle of the stream, the distance between the part and the projection system, the strength, and coverage. The shot peening strength, measured in Almen degree, was measured on two sides of a layered specimen (76 x 19 mm) obtained from a C 70 UNI 7845 killed steel hardened and tempered at 44 ÷ 45 HRC in the direction of stream injection Quot; s "can take on three different values corresponding to a weak intensity N, a medium intensity A and a strong intensity C short peening. The curvature resulting from the stream of shots is measured by a quadrant comparator.

The coverage is determined by applying a stream of shots to the polished specimen for a time corresponding to the relevant intensity and measuring the area of all collided regions within a circumference having a conventionally set diameter at 50 times magnification, Is defined as the ratio between the sum of the areas of the areas and the area of the area.

The second step of subjecting the at least one portion of the surface of the previously washed at least one portion to a shot peening treatment is performed with an S110 steel ball having a diameter of between 0.01 mm and 1.5 mm, A ball having a diameter of the optimum processing result observed in the method according to the present invention is used.

The second step of performing the shot peening process on the at least one portion of the surface of the at least one element that has been previously cleaned is to determine the intensity with a value of 4 to 20 탆 for the A-type specimen Lt; / RTI > peening).

Even in this case, it is appropriate that the ideal value of the pinning strength referenced to the intermediate strength of the pinning indicated by the letter A and identified by the letter A is approximately 6 or 8.

In any case, the second step of shot peening is performed by providing a coverage of greater than 60%, while an optimal result is obtained at 100% of the at least one portion.

By the third step of the method according to the invention, which forms a molybdenum disulfide layer on the at least one part of the at least one element, a layer of 1 to 50 탆 thick is provided.

Even in this case, it is convenient that the ideal thickness of the molybdenum disulfide within the range of the method according to the present invention is 5 to 15 占 퐉.

In said third step of forming a molybdenum disulfide layer on said at least one portion of at least one element, an aerosol comprising at least 10% by weight of molybdenum disulfide, inorganic resin, solvent and propellant is routed to said at least one portion .

It is desirable to use an aerosol having a content of molybdenum disulfide of greater than 20% to obtain better results and also to obtain a more efficient and stable layer in the treated portion of the element.

A combination of the steps indicated and provided by the method according to the invention is particularly effective since the surface conditioning defines the ideal conditions for the adhesion of the molybdenum disulfide layer.

At the same time, shot peening generates a plurality of continuous microcavities on the outer surface of the element.

Due to the surface irregularities, adhesion of molybdenum disulfide is facilitated, and deposits of a higher thickness, which increase the structural strength, are locally produced.

Also, with respect to the same smooth surface, the surface affected by the plurality of continuous cavities without discontinuity has a larger area, so that the contact area between the molybdenum disulfide and the surface itself increases, and the toughness of the adhesion of molybdenum disulfide Is directly proportional to the area of the surface to be coated, so that irregular surfaces result in stratification of higher stability.

Finally, the residual tension caused by the shot peening step ensures a higher stiffness of the element surface.

Since deformation can cause delamination, the less undeformed element is better suited for subsequent deposition of a layer of rigid material.

Therefore, the combination of the steps entails a synergy combination which ensures the superposition of the effects shown and the effectiveness of the remarkable mechanical coupling in terms of strength, durability and mechanical performance of the molybdenum disulfide layer.

The method according to the invention comprises an auxiliary step of removing material from the other of the two elements to increase the clearance between the two elements connected to each other.

In this case, removal of the material occurs in at least one of the other elements, which is not opposed to and not near the at least one portion through the first through third steps.

By the removal of the material, the sliding between the two (or more) elements takes place only at the part to which the invention is applied, and in fact the other part is separated at a considerable clearance, Is obtained by further removal.

Moreover, due to the increased clearance, a greater amount of lubricating oil (oil or grease) may be contained within this clearance. The lubrication oil is isolated by the respective sealing element of the usual kind within the free space (gap) existing between the elements, and no specific description thereof will be required (because it is known).

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a front sectional view of a possible rotatable mechanical coupling provided by applying a method of inhibiting galls in accordance with the present invention, taken along a transverse plane.

According to a particular application according to the present invention, which allows a simple and immediate confirmation of many of the advantages and possibilities of the present invention, the first element consists of a pivot 2 and the second element consists of a bushing 3.

In use, the pivot 2 is rotatably inserted in the bushing 3 and has at least one portion 4 that slides in a corresponding region of the inner surface of the bushing 3, .

The bushing 3 has been machined off at one portion of the inner surface to form a cavity 5 of larger diameter.

In this way, the clearance 6 can be formed between the pivot 2 and the region 5 of the bushing 3 (this can have a large dimension).

Within the clearance 6, a predetermined amount of lubricating oil that facilitates the relative rotation of the pivot 2 and the bushing 3 can be isolated.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings relate in particular to the operable coupling of links in chains which are interconnected.

In particular analysis of the arrangement given as an example, in this case the links 7, 8 of the chain are keyed to the bushing 3 with a certain interference.

Similarly, two different links 9 and 10 (opposite those which are integral with the bushing 3) are keyed to the pivot 2 with a certain amount of interference.

Actually, according to the above-mentioned configuration, the pivot 2 and the assembly of the links 9, 10 constitute the first joint part, and the bushing 3 and the assembly of the links 7, 8 constitute the second joint part .

The two joint portions constitute a mechanical coupling which is particularly efficient when the method according to the present invention is applied to said portion (4) of the pivot (2) sliding on the inner surface of the bushing (3).

Finally, a sealing element (not shown) is interposed between the pivot 2 and the bushing 3 in order to isolate the lubricant to the clearance 6 formed between the pivots 2 and the area of the larger diameter of the cavity in the bushing 3. [ 11 and 12 are used.

Chains of the kind shown in the accompanying drawings are commonly used for soil mover and many other industrial processes.

The method according to the invention can in any case be applied to a considerable number of other mechanical couplings and joints which are usually gorged due to the speed and frequency of the applied mechanical tension and / or relative motion.

Advantageously, the present invention proposes a method of inhibiting the golfer to treat the material, which can minimize the occurrence of the golfer to a negligible extent, and solves the problems described above.

This result is obtained by a shot peening step and a synergistic effect of the residual compression state due to the presence of the molybdenum disulfide layer.

Advantageously, by means of the method of inhibiting goring according to the invention, the risk of golping of the rotating pivot 2 with respect to the mating bushing 3 is minimized and is thus particularly effective in the case of rotational coupling.

Efficient, the method of inhibiting goring according to the present invention can reduce the periodic maintenance of the mechanical coupling including the elements to which the method is applied.

In fact, the number of maintenance interventions required can be greatly reduced due to the reduction of the occurrence of the golning phenomenon and the presence of the clearance 6 (as compared to the coupling of the traditional kind).

Preferably, the method of inhibiting galling according to the present invention can be performed at a substantially lower cost, is relatively simple to provide in practice, and is safe in application.

The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the appended claims, all details being replaced by other elements which are technically equivalent.

In the example of the illustrated embodiment, the individual features given in connection with the specific example may be interchanged with other features actually present in other examples of the embodiment.

In practice, the materials and dimensions used may be any according to the requirements and the state of the art.

Where reference is made to the technical elements recited in the claims, the reference signs are included solely for the purpose of assisting the understanding of the claims, and such reference signs are, for example, interpreted Lt; / RTI >

Claims (10)

A galling suppression method for treating a material, comprising: a first preliminary heat treatment step for increasing the surface hardness of at least one of at least two elements connected to each other at least in one freedom and made of a metallic material; A preliminary surface grinding step is carried out,
- carrying out a first step of cleaning at least one part of the surface of the at least one element which has been subjected to the preliminary step,
Performing a second step of performing a shot peening process on said at least one portion of the surface of said at least one element that has been previously cleaned,
- performing a third step of forming a molybdenum disulfide layer on said at least one part of said at least one element which has been previously subjected to a shot peening treatment. The method according to claim 1,
Wherein the first cleaning step further comprises surface degreasing at least one portion of the surface of the at least one element that has undergone the preliminary step. The method according to claim 1,
Said second step of effecting a shot peening treatment on said at least one part of the surface of said at least one element which has been previously washed is repeated until a residual compression state of 200 MPa to 10000 MPa is obtained in said at least one part, A method of inhibiting galling for treating a material. The method according to claim 1,
Said second step of performing a shot peening process on said at least one portion of the surface of said at least one element that has been previously washed is carried out with an S110 steel ball having a diameter of from 0.01 mm to 1.5 mm, . The method according to claim 1,
Said second step of performing a shot peening process on said at least one portion of the surface of said at least one element that has been previously cleaned is carried out with an intensity having a value of from 4 to 20 Almen degrees for the specimen A, Gt; The method according to claim 1,
Wherein the second step of performing a shot peening process on the at least one portion of the surface of the at least one element that has been previously cleaned is performed with a coverage of greater than 60 percent of the at least one portion, Golging inhibition method. The method according to claim 1,
A layer of 1 to 50 占 퐉 thickness is formed by said third step of forming a molybdenum disulfide layer on said at least one portion of at least one element. The method according to claim 1,
In the third step of forming the molybdenum disulfide layer on the at least one portion of the at least one element previously subjected to the hot-peening treatment, an aerosol containing molybdenum disulfide, inorganic resin, solvent and propellant in an amount of more than 10% Wherein the at least one portion is roughened. The method according to claim 1,
And a sub-step of removing material from the other of the two elements to increase the clearance between the two elements connected to each other, wherein removal of the material is carried out through the first through third steps Occurs in at least one region that is not opposed to and not adjacent to said at least one portion. The method according to claim 1,
The first element is the pivot 2 and the second element is the bushing 3. In use the pivot 2 is rotatably inserted within the bushing 3 and the inner surface of the bushing 3 And at least one portion (4) sliding in a corresponding region and going through a first to a third step.

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