ES2351085T3 - PROCEDURE AND DEVICE FOR INSULATING AN AREA OF THE SURFACE OF A PIECE. - Google Patents

Abstract

Procedure for the treatment of the surface of a spherical journal (12) by means of a device to isolate an area of the surface (2) of the spherical cylinder (12) against a gaseous medium, a procedure in which a) the spherical journal (12 ) is partially housed through an opening (5) in a hollow chamber (4) of the device and b) the hollow chamber is waterproofed with means (6) for waterproofing, whereby during the treatment of the surface of the spherical journal (12 ) the penetration of the medium into the hollow chamber (4) is prevented, characterized in that c) as a device for insulating a cover sheath (7) is used, which includes a joint element (61) arranged in the opening area ( 5) of the hollow chamber (4), d) the part (3) being fixed by means of a thread (11) in a threaded hole (71) of the cover sheath (7), the joint element (61) interacting tightly ) with an outer contour (21) of the spherical journal (12) and e) nitriding or nitrocarburizing an area (31) of the surface of the spherical journal (12), f) at a temperature between 350 ° C and 900 ° C g) by a gas nitriding process and / or a plasma nitriding process.

Description

Procedure and device to isolate a zone of the surface of a piece.

The invention relates to a method for the treatment of the surface of a spherical journal according to the preamble of claim 1.

The improvement of the finish of surfaces subject to solicitations, in particular surfaces of metal parts, by very different procedures. An improvement of the finish can be achieved, among others, for example by applying a protective layer of dye, by chrome plating, galvanized or applying a layer of oxide or ceramic. It can often be improved in particular the behavior regarding corrosion and wear of parts subject to strong solicitations of materials based on iron properly modifying the surface layer of the piece. In this regard, procedures in particular have been accredited which the state of the surface structure of a piece to iron base is modified by enriching it with nitrogen and / or carbon, with eventual subsequent oxidation, in order to improve resistance behavior for solicitations static and oscillating and / or wear behavior, the behavior in terms of variation of the form and the behavior regarding corrosion of the surface of the piece. Accredited procedures of this type are for example nitriding procedures with gas or liquid or procedures of nitriding with plasma or also a combination of procedures mentioned above and in particular processes of carbonitruration or nitriding in salt bath, which have spread as applications to improve, harden and protect against corrosion or to improve the tribological behavior of surfaces subject to solicitations.

Then there is often the problem that only a part of the surface of a piece must be treated, for example in a gas atmosphere or in a liquid bath and other part determined from the surface no.

This is how the improvement has been known for a long time of the surface finish of spherical caps for systems translation mechanisms, for example for steering arms cross-sections of motor vehicles in a process of carbonitriding in gas or in a liquid bath by nitriding in salt bath. Such spherical caps are composite parts essentially by a tree or shaft shaped approximately cylindrical, which at one end presents along an area determined a thread and its other end is configured as sphere, so that the sphere can interact with a bearing of kneecap of the trailing translation mechanism. Since the sphere, when mounted and in service, is subject to considerable efforts and in particular also loads tribological, it is necessary to harden at least the area of the ball bearing sphere surface, for example in a gas nitrocarburization process in a process chamber or in a liquid bath by nitriding in salt bath.

However, until now it was almost always treated the entire surface of the spherical journal, that is, in particular also the threading area. But the treatment by surface nitriding in a nitriding process or Carbonitruration has a negative impact on the threading area. In a nitriding of a surface area in a process of nitriding thin surface layers are formed, the so-called tie layers with thicknesses of the order of micrometers, since, in particular when there are transverse loads and when they act strong frictional forces, such as those presented on all when screwing into a thread, they can form microcracks in the threading area.

Therefore, in carbonitruration in gas, covered the threading area with a protective paste against the nitriding, which then had to be removed again after the process of nitriding in gas with a considerable cost. In addition, the covering a surface area that is not to be coated with a plastic medium, such as with a protective layer against nitriding, is totally inappropriate for many procedures covering. Thus a protective paste can dissolve in the salt bath nitriding in the nitriding bath liquid, with what on the one hand the nitriding bath gets dirty and on the other side loses surface protection function. But neither in procedures for surface treatment that have to be performed in a process chamber under conditions of depression, as for example, in PVD procedures (Physical Vapor Deposition, known vapor deposition), is desirable by Usually the use of protective pastes to cover areas of the surface that are not to be coated, since the paste of protection, due to its vapor pressure, can vaporize in considerable measure, which on the one hand the necessary depression in the process chamber it can only be maintained at a high cost and on the other hand, when the protective paste vaporizes, they are free surface areas to protect.

From US 6224,673 B1 a known device and a procedure to mask components of turbine during a gas phase diffusion coating. For masking the turbine blade socket a camera is used hollow to which the turbine blades with their surface are subjected rectangular base. If necessary, the camera is waterproofed hollow by waterproofing, such as a means of sealed, facing the atmosphere of the coating.

From DE 1 053 013 a known procedure to avoid or regulate the absorption of carbon in the carbonitriding of dust or gas. In this regard, an area is housed protect from a piece in a hollow chamber. In the hollow chamber it Find a substrate that emits oxygen. In carburetion with carbon monoxide, the carbon monoxide that diffuses is oxidized in the hollow chamber, so that carburetion cannot be performed in the protected area.

From US 2,179,073 a known procedure for the carburation of metallic objects. In this procedure the object to harden is housed in a sheath and to It is then surrounded by a carbon dispenser.

From WO 02/066698 a known device for partial carburetion of parts. This device surround the part to be partially protected and with a very interstitium narrow. The sheath material has a coefficient of expansion thermal inferior to that of the material of the piece to protect, with what when it warms up the interstitium closes and diffusion is prevented into the carburetion gas.

For US 3,740,259 and US document 3,631,837 methods for coating or varnishing are known containers To protect parts of the container, for example in proximities of the pouring mouth, facing dyes or material of coating, the container is screwed before coating on a protective sheath.

By the JP 60-204 procedure 879 a procedure is known to protect a piece against a atmosphere in which the piece is introduced through an opening narrow in a hollow chamber. When heating the sheath and the piece is both expand to a different extent, which eventually closes remaining interstices

By WO 90/10809, EP 0 863 288 A2 and US 6,176,934, other boards are known.

Therefore the task of the invention is propose a simple procedure for the treatment of part of the surface that can also be used with depression in the process chamber

The invention solves the problem by means of a method according to claim 1.

The corresponding claims Dependents refer to constructive forms of the invention especially advantageous.

To perform the procedure corresponding to the invention is suitable a device that is proposed to then to isolate an area from the surface of a piece regarding a fluid medium. The device features a hollow chamber with an opening to house the part, being provided means for waterproof the hollow chamber, which during treatment of the surface of the piece the penetration of the medium can be avoided fluid in the chamber

The device thus presents a hollow chamber with an opening, the hollow chamber being preferably provided in a metal cover sheath, the sheath may be constituted of cover obviously also by other suitable material, by example by a plastic, a ceramic material or a vitreous material. The hollow chamber of the device is then configured such that it can accommodate a part of the piece whose surface area does not it has to be treated in a surface treatment of the piece. For this, they are preferably provided in the opening of the hollow chamber means to waterproof the hollow chamber, which they include a gasket element, in particular an annular gasket, which It is configured and arranged in the area of the camera opening hollow such that it can interact by waterproofing with a outer perimeter of the piece such that the hollow chamber and with it the area of the surface of the piece that is arranged inside the hollow chamber are isolated from a fluid medium that is out of the hollow body. Then it is perfectly possible that the hollow chamber is waterproofed in the opening area by means of a plastically deformable medium, in particular by a paste of protection against nitriding on an outer perimeter of the piece. Then you can support the protective paste against the nitriding of the joint element in its sealing effect, or even by itself assume the function of a means to waterproof the hollow chamber in the area of the opening.

Then the means for waterproofing also by thermal expansion of the hollow body and / or joint element. For example you can choose as a material for the hollow body and / or for the joint element a material that has a different thermal expansion coefficient to the material of the piece. If the surface treatment of the piece is made at a different treatment temperature than the room temperature, for example at a treatment temperature clearly above or below room temperature, then, when the configuration of the piece in the opening correspondingly configured from the hollow chamber of the device corresponding to the invention is suitable, they can interact in drag the part and / or the joint element and the opening of the hollow chamber such that due to the different coefficients of thermal expansion results, when the temperature is different from the room temperature, the corresponding sealing effect.

Within the framework of the invention the piece is a spherical journal, which in a known way encompasses a tree or axis with threaded and a section of sphere, the latter being able to interact in Drag with a spherical bearing. To improve hardness and / or the tribological or other characteristics of the surface of the section of sphere, its surface is nitrated preferably in a reaction vessel in a gas or liquid fluid, that is, The surface is improved by nitriding. In particular it has place the surface nitriding process in an atmosphere of gas according to a procedure known per se by nitrocarburization Within the framework of the invention the procedures mentioned above in a temperature range between 350ºC and 900 ° C, preferably between 500 ° C and 600 ° C. To avoid also the surface of the spherical bore thread zone is subject to nitriding, the threading area of the journal is placed spherical in the hollow chamber of the device, presenting the device in a preferred embodiment in the opening of the hollow chamber, as a joint element, a toroidal ring elastically or plastically deformable, configured and arranged such that it interacts with an outer contour of the tree or axis of the spherical journal Obviously the device can be used analogous way for the partial coating of a surface of any piece, even of a non-metallic piece, being correspondingly configured the hollow chamber and the opening of the device to house the piece.

In another example of execution includes the suitable device to perform the corresponding procedure to the invention an additional equipment to support the function of seal element seal. In this regard it can be treated in Particular of an additional mechanical, pneumatic or hydraulic equipment. In this regard, for example, additional mechanical equipment simple, like a tightening ring that allows pressure on the joint element in an outer perimeter of the piece.

The corresponding device can then also include additional pneumatic or hydraulic equipment. By example may include the gasket element a hollow hose elastically extensible, which is joined by a system of pipes with a hydraulic or pneumatic feeding equipment that subjects the joint element by means of a fluid pressure means that can be carried to the joint element through the piping system with a working pressure such that the hose elastically Extensible is tightened properly on the perimeter outside of the piece, which can increase the effect of tightness In this regard they can be used as materials for elastic hose preferably materials for high temperatures, such as plastics for high temperatures, for example Carbon fiber reinforced materials such as PEEK (polyether ketone) or other suitable materials. In the elastic hose may be constituted, with a proper configuration, also by a metallic material. A joint element that can undergo the working pressure can be especially advantageous when in the process chamber, by example in an ionization chamber, a depression reigns significant, so without an additional support team the effect The sealing element seal is not enough.

In this regard, in an example of execution preferably, the elastically extensible hose is arranged and executed such that the piece, while the hose is not subjected to The working pressure of the fluid pressure medium, can be accommodated without special effort through the opening in the hollow chamber of the device and the elastically extensible hose just squeezes drag tightly over the part when it is subjected to working pressure.

As already mentioned, the treatment of the surface of the piece is usually done in a chamber of reaction or in a process chamber. The process chamber can then include one or more loading equipment, presenting supports to accommodate one or more pieces, being provided in the device equipment to fix the device on a stand. When he device, as described above, includes equipment Additional pneumatic or hydraulic, is subjected to working pressure of one or more devices preferably centrally through a feeding device through a system distributor, which is connected by a pipe system with the devices arranged on the charging equipment in the chamber of process.

Within the framework of the invention a procedure for the treatment of the surface of a piece by means of a device to isolate an area of the surface of the piece of a fluid medium. In the procedure the piece is introduced partially through an opening in a hollow chamber of the device and is waterproofed with means to waterproof the hollow chamber In this way it is avoided during the treatment of surface of the piece the penetration of the fluid medium in the chamber hollow

In this regard it includes the procedure corresponding to the invention for surface treatment of a piece a procedure in which an area of the surface of the part is subjected to nitriding or nitrocarburization, in particular through a gas nitriding process.

The invention will be described below in detail based on the drawing. Shown in schematic representation in:

Figure 1 a suitable device to perform the procedure corresponding to the invention with a piece;

Figure 2 a longitudinal section through a suitable device to perform the corresponding procedure to the invention with joint element;

figure 3 as figure 2 with a team additional and a feeding equipment.

Figure 1 shows an example of execution of a device that will then be named as a whole with reference 1, together with a spherical journal 3 for a system of translation mechanism shown in figure 1 as example for a piece 3. Obviously the explanations that they are still worth the same for any piece 3 that may be It also consists of a non-metallic material.

Device 1 includes a cover sheath 7 preferably metal with a hollow chamber 4, suitable for partially accommodate a part 3. Part 3 includes a section I whose surface is treated by the action of a fluid medium, as well as a section II whose surface area 2 is not to be treated. At example shown here should be treated spherical journal 3, which essentially includes a cylindrical shaft or shaft 32 with a sphere K and a threading 11, preferably in an area 31 of the surface of the K sphere, while the surface area 2 of the journal spherical 3 must not be treated in section II, which includes essentially a thread 11 of the spherical journal 3. To achieve this, the zone II of the threading 11 of the spherical journal 3 is arranged in the hollow chamber 4 of the cover sheath 7. Preferably it is fixed the spherical journal 3 in the cover sheath 7 with the thread 11 in a threaded hole 71. Then it presents the opening 5 of the cover sheath 7 means 6 to waterproof the hollow chamber 4 of the cover sheath 7, which include a joint element 61 preferably configured as a seal ring. Seal ring is then arranged and configured in the area of the opening 5 of the hollow chamber 4 such that it interacts with an outline exterior 21 of spherical journal 3, generating tightness. By example the joint element 61 can be configured as a ring elastic, in particular as a plastic toroidal ring suitable. Then can the joint member 61, as is will describe later, have additional equipment 62 not shown in figure 1 to support the sealing function of the joint element 61, which increase the effectiveness of the seal and facilitate the removal of the cover sheath 7 after surface treatment. In this regard proceed for example simple mechanical equipment such as a clamping ring or a band of tightening, which allows the joint element 61 to be pressed on the outer perimeter 21 of part 3. In this regard they may be means 6 for sealing are also made by means of a thermal expansion of the cover sheath 7 and / or the element of board 61. For example, it can be chosen as a material for the sheath of cover 7 a material that has a coefficient of expansion thermal greater than that of the material of part 3, that is, here the spherical journal 3. Treatment of the surface of the journal spherical 3 is performed at a treatment temperature considerably higher than room temperature, precisely at a treatment temperature between 350 ° C and 900 ° C. That's why it expands cover sheath 7 when heating from temperature ambient to the treatment temperature in the direction of a longitudinal axis A-A that runs axially more strongly than the spherical journal 3. Since the spherical journal 3 is fixed with the thread 11 in the cover sheath 7 in the threaded hole 71, an area of the edge 72 of the opening is squeezed 5 of the cover sheath 7 against the tree 32, due to the different thermal expansion between cover sheath 7 and the spherical journal 3, so that the hollow chamber is waterproofed 4. That is, due to the different thermal expansion of the journal spherical 3 and / or cover sheath 7 and / or joint element 61, the sealing effect of the joint element can be increased 61.

Usually the treatment of the surface of spherical journal 3 in a process chamber no shown, in which usually supports are provided, which in particular may be associated with a charging device, to accommodate one or more spherical caps. Device 1 presents therefore equipment 10 to fix the device 1 in the holder. He equipment 10 may in particular have a screw or a bayonet closure or other suitable means to fix the device 1 on the stand

In figure 2 it is schematically represented a longitudinal section through a device 1. The device 1 includes cover sheath 7 in which it has been housed a section II of part 3. In addition, part 3 presents a section I, whose surface 31 must undergo a surface treatment by a fluid medium, while the surface area 2 Section II should not be treated. 6 means are provided for waterproof the hollow chamber 4, the means 6 being made as joint element 61, which is configured and arranged in the opening area 5 of the hollow chamber 4 such that it can interact tightly with an outer perimeter 21 of part 3. The joint element 61 is then preferably performed as metal seal ring, for example of soft iron, copper, aluminum, brass or other alloy and can cover tightly for example as a toroidal ring when the assembly is mounted the perimeter 21 of the part 3. Obviously the joint element 61 also by other materials, for example by a suitable plastic, in particular by a high plastic temperature, such as carbon fiber reinforced materials, such as for example PEEK (polyether ether ketone), or also by materials ferric metal, such as steel, or a material ceramic or any other suitable material. The joint element 61 it can obviously also contain a metal ring of tightness, which you can present for example to increase the sealing function a coating 63, including the coating 63 a suitable material, for example one of the materials mentioned above or, depending on the application corresponding, a plastically deformable medium, such as a plastically deformable metal or a paste, in particular a nitriding protection paste. Obviously they can also present the non-metallic joint elements 61 a coating 63. Then the means 6 for the tightness also by thermal expansion of the sheath of cover 7 and of the joint element 61. For example, it can be chosen as material for cover sheath 7 a material that presents a coefficient of thermal expansion lower than the material of the piece 3. If the surface treatment of the spherical journal 3 it takes place at a treatment temperature considerably above room temperature, such as a temperature of treatment between 350ºC and 900ºC, then the gasket of cover 7 when heating from room temperature to treatment temperature in the direction of a transverse axis B-B that runs radially less strongly than piece 3 in the corresponding direction. With it and due to the different thermal expansion between the cover sheath 7 and the piece 3, press the outer perimeter 21 of part 3 against the joint element 61, whereby the sealing effect of the joint element 61 can be increased. In particular you can by example also present the joint element 61 another value, in particular a greater value of the expansion coefficient than the piece 3 and / or the cover sheath 7, whereby the joint element, at increase the temperature, it is compressed tightly against the perimeter 21 of part 3 and cover sheath 7.

In figure 3 another schematic is shown exemplary embodiment of a device 1 suitable for performing a procedure corresponding to the invention, which includes equipment additional 62 to support the sealing function of the element gasket 61, in particular an additional pneumatic or hydraulic equipment 62. Device 1 includes cover sheath 7 in which it houses a section II of a piece 3. In addition, it presents part 3 a section I, whose surface 31 has to undergo a treatment superficial by means of a fluid medium, while the area of the Surface 2 of section II must not be treated. The planned means 6 to waterproof the hollow chamber 4 in the opening 5, they are made as joint element 61 with a hollow area 65, the joint element 61 presenting an extensible zone elastically 64.

In one form of execution the zone is made hollow 65 as an elastically extensible closed annular body and hollow, filled with a fluid, for example air. In this regard it is performed the annular body such that the annular body, due to the thermal expansion of the fluid, when the temperature rises you see subjected to an internal pressure such that the elastic annular body extensible presses properly on the outer perimeter 21 of the piece, which increases the sealing effect of the joint element 61 to achieve the tightness of the hollow chamber 4. Such an annular body can obviously be used successfully also in a process chamber that presents with respect to pressure internal body cancel a depression, which, due to the pressure difference of the elastically extensible annular body, it tighten properly on the outer perimeter 21 of the piece, thereby increasing the sealing effect of the element of joint 61 to waterproof the hollow chamber 4.

The joint element 61 with the hollow zone 65 It can also be made as an elastic hose extensible, the hollow zone 65 being able to be subjected by a system of pipes 8 at a working pressure of a fluid pressure medium 13, whereby zone 64 elastically extensible of the element of gasket 61 or the elastically extensible hose can tighten properly the outer perimeter 21 of the piece, with what which increases the sealing effect of the joint element 61 for waterproof the hollow chamber 4. The hollow zone 65 is joined via the piping system 8 with a feed unit hydraulic or pneumatic 9, which in particular includes a system of distribution 14 which is suitable for feeding one or several devices 1 with the fluid pressure medium 13 and subject it to a work pressure.

By using the aforementioned device It is possible in a very simple way to carry out a treatment of the surface of a piece in a fluid medium, except for the treatment a part that can be predetermined from the surface of the piece. Thus the device can be used for example with special success for the treatment of the surface of a sphere of a spherical journal in a nitriding or nitrocarburization process in which a surface treatment of the area should be avoided Threading This avoids the configuration of the called tie layers in the threading area, which in particular when there are transverse loads and when large forces of friction, such as those that occur especially in the screwing a thread, can lead to the formation of microcracks in the threading area.

The threading area cover known for the state of the art with a nitriding layer, which has to withdraw at a considerable cost again after the process of gas nitriding is suppressed using the device described. In addition, the device proposed here can also be used without problems in coating procedures where it is not possible to partially cover the surface with a paste of nitriding or other fluid plastic medium. Through equipment additional, particularly by means of additional pneumatic equipment or hydraulic, the sealing effect of the means to waterproof or can be controlled and / or regulated, subjecting the additional equipment to a working pressure, the sealing effect of the means for waterproofing by A central feeding team.

Claims (3)

1. Procedure for the treatment of surface of a spherical journal (12) by means of a device for insulate an area of the surface (2) of the spherical journal (12) facing to a gaseous medium, procedure in which

to)

he spherical journal (12) is partially accommodated through an opening (5) in a hollow chamber (4) of the device and

b)

the hollow chamber is waterproofed with means (6) to waterproof, with what during the treatment of the surface of the journal spherical (12) prevents penetration of the medium into the hollow chamber (4),

characterized because

C)

how device for insulating a cover sheath (7) is used, which includes a joint element (61) arranged in the area of the opening (5) of the hollow chamber (4),

d)

fixing the piece (3) by means of a threaded (11) into a threaded hole (71) of the cover sheath (7), tightly interacting the joint element (61) with a outer contour (21) of the spherical journal (12) and

and)

nitriding or nitrocarburizing a zone (31) of the surface of the spherical journal (12),

F)

to one temperature between 350ºC and 900ºC

g)

through a nitriding process in gas and / or a plasma nitriding process.

2. Method according to claim 1, in the one who the area (31) of the surface of the journal spherical (12) is further oxidized. 3. Procedure according to one of the preceding claims, characterized in that the process is performed at a temperature between 500 ° C and 600 ° C.