Patent Application
20140193286
The invention relates to a method for the production of a treatment element, in particular a screw and/or kneading element for a screw machine. The invention further relates to a treatment element blank for the production of a treatment element, in particular a screw and/or kneading element for a screw machine, comprising a treatment element core of a first metal material and an anti-wear layer of a second metal material surrounding the treatment element core, wherein the second material is combined with the first material by hot isostatic pressing to form a composite body.
A method for the production of a screw shaft by hot isostatic pressing is known from DE 43 28 160 A1. In order to produce the screw shaft or the screw element, a steel core and a sleeve of a corrosion-resistant and wear-resistant material disposed around said steel core are arranged in a pressing mold in such a way that a slot-like annular space having a constant slot thickness is formed between the sleeve and the inside of the pressing mold. Afterwards a metal powder is introduced in the annular gap and then compressed to form a screw flight front layer. The screw flight front layer is formed by hot isostatic pressing in such a way that it forms one piece with the sleeve and the sleeve forms one piece with the steel core. The blank produced by hot isostatic pressing has three hollow-cylindrical interconnected layers of a constant thickness and is machined after cooling in such a way that the screw flight and the screw flight front layer connected thereto are produced. Since the sleeve is at first relatively soft for machining, the screw element produced after machining is furthermore subjected to heat treatment. The drawback of this method is that the described production method requires a great amount of effort. In particular when the heat treatment is performed, attention must be paid to internal stresses in the screw element to reduce or prevent the formation of stress cracks after heat treatment.
It is an object of the invention to provide a simpler method for the production of a treatment element for a screw machine.
This object is achieved by a method for the production of a treatment element for a screw machine, the method comprising the following steps:
It was found according to the invention that the production or reproduction of a treatment element is much simpler if the annular space formed between the capsule wall and the treatment element core is contoured along the central longitudinal axis or in a sectional plane extending through the central longitudinal axis so as to be adapted to an outer contour of the treatment element to be formed. Since the second material is used for forming an anti-wear layer of the treatment element, said material is a high-alloy and extremely wear-resistant and/or corrosion-resistant material which is correspondingly expensive. Because of the contoured design of the annular space, an anti-wear layer adapted to the outer contour of the treatment element to be formed is already produced during hot isostatic pressing, which reduces both the volume and the amount of material required for the second material and simplifies post-processing of the treatment element blank produced by hot isostatic pressing, in particular facilitating the machining processes for producing the outer contour of the treatment element and/or the heat treatment of the anti-wear layer which is required depending on the subsequent use. The treatment element may be a screw and/or a kneading element. The treatment element core arranged in the capsule may be formed of a solid material or it may be provided with a through-hole.
Since the anti-wear layer according to the production method disclosed in DE 43 28 160 A1 is produced from the sleeve prefabricated by hot isostatic pressing and from the screw flight front layer produced by hot isostatic pressing, a considerable material volume of high-alloy and wear-resistant and/or corrosion-resistant materials is required while resulting in a considerable amount of effort required for post-processing the blank to form the finished screw element. Compared to the production method according to the invention, the prior art method requires an additional production step since the sleeve is prefabricated by hot isostatic pressing. Furthermore, a considerable material volume of the wear-resistant and/or corrosion-resistant materials needs to be removed by machining, which makes post-processing more elaborate. Moreover, when the screw element produced by machining is subjected to subsequent heat treatment, care must be taken to prevent stress cracks from forming in the anti-wear layer during heat treatment as a result of the greatly varying thickness of the anti-wear layer.
In the production method according to the invention, the contoured anti-wear layer of the treatment element blank is adapted to the outer contour of the treatment element, which simplifies post-processing since the material volume to be removed is significantly reduced and/or the anti-wear layer has a substantially constant radial thickness along the central longitudinal axis of the treatment element, allowing the formation of stress cracks during heat treatment to be prevented.
A method, in which the treatment element core is provided with a contour on a core outer side for producing the contoured annular space, provides a simple way of providing the anti-wear layer with a contour on an anti-wear layer inner side facing the treatment element core. This reduces the material volume required for the anti-wear layer and therefore the material quantity required for the second material. Furthermore, this ensures that the anti-wear layer has a substantially constant thickness along the central longitudinal axis which simplifies heat treatment.
A method, in which a core outer side has a radial distance from a central longitudinal axis of the treatment element core which radial distance varies along said central longitudinal axis, provides a simple way of forming a contoured annular gap along the central longitudinal axis or in a sectional plane extending through the central longitudinal axis. The radial distance between the outside of the core and the central longitudinal axis varies between a minimum distance and a maximum distance.
A method, in which a capsule wall inner side of the capsule wall is cylindrical, provides a simple way of forming a contoured annular space along the central longitudinal axis or in a sectional plane extending through the central longitudinal axis. The constant radial distance between the capsule wall inner side and the central longitudinal axis and the varying radial distance of the treatment element core from the central longitudinal axis result in a contoured annular space which has a thickness that varies along the central longitudinal axis. The thickness varies between a minimum thickness and a maximum thickness.
A method, in which the treatment element blank is formed by machining in such a way that a treatment element outer contour is produced, allows an anti-wear layer to be produced that has a substantially constant thickness along the central longitudinal axis. After the removal of material, the radial distance of the anti-wear layer outer side varies along the central longitudinal axis between a minimum radial distance and a maximum radial distance.
A method, in which a capsule wall inner side of the capsule wall is provided with a contour for producing the contoured annular space, provides a simple way of forming a contoured anti-wear layer outer side facing the capsule wall. On the one hand, this reduces the material volume required for the anti-wear layer. On the other hand, this greatly simplifies post-processing since the outer contour of the treatment element blank or of the treatment element is already produced by hot isostatic pressing. If necessary, the outer contour needs to be fine machined.
A method, in which a capsule wall inner side of the capsule wall has a varying radial distance from the central longitudinal axis, ensures that the anti-wear layer outer side facing the capsule wall is provided with a contour along the central longitudinal axis or in a sectional plane extending through the central longitudinal axis.
A method, in which the treatment element blank is produced in such a way as to be provided with a treatment element outer contour and that an anti-wear layer outer side only requires fine machining during post-processing, ensures a simple production of the treatment element.
A method, in which a core outer side of the treatment element core has a constant radial distance from a central longitudinal axis along said central longitudinal axis, ensures a simple provision of the treatment element core.
A method, in which, in order to produce the contoured annular space, a capsule wall inner side of the capsule wall and a core outer side of the treatment element core are provided with a contour, allows an anti-wear layer to be produced which is provided with a contour both on the anti-wear layer inner side and on the anti-wear layer outer side. As a result, the material volume required is on the one hand greatly reduced, allowing the anti-wear layer to be produced from a low material quantity of the second material. On the other hand, post-processing is extremely simplified since the outer contour of the treatment element blank or of the treatment element is already produced during hot isostatic pressing. Moreover, the anti-wear layer has a substantially constant radial thickness along the central longitudinal axis which simplifies heat treatment and prevents the formation of stress cracks.
A method, in which a capsule wall inner side and a capsule wall outer side of the capsule wall are provided with a contour, provides a simple way of forming and removing the capsule.
A method, in which a capsule bottom and a capsule cover are provided with through-openings which are arranged concentrically to each other for producing a treatment element blank having a through-hole, allows a treatment element blank to be produced with a through-hole.
Another object of the invention is to provide a treatment element blank which provides a simple way of producing a treatment element for a screw machine.
This object is achieved by a treatment element blank, in which the anti-wear layer is provided with a contour along a central longitudinal axis. Since the anti-wear layer is provided with a contour, the production of a treatment element from the treatment element blank is greatly simplified. The treatment element blank is the composite body produced directly by hot isostatic pressing without any further post-processing. The contoured anti-wear layer simplifies machining of the treatment element blank to form the outer contour and/or heat treatment of the treatment element after formation of the outer contour. The anti-wear layer is contoured along the central longitudinal axis or in a sectional plane extending through the central longitudinal axis. The other advantages of the treatment element blank according to the invention are the same as those of the method according to the invention already described above.
Furthermore, the advantages of the treatment element blank, in which a core outer side of the treatment element core facing the anti-wear layer is provided with a contour, in which a core outer side has a radial distance from a central longitudinal axis of the treatment element core that varies along the central longitudinal axis, in which the treatment element blank has a cylindrical blank outer side, in which an anti-wear layer outer side of the anti-wear layer facing away from the treatment element core is provided with a contour, in which a core outer side of the treatment element core facing the anti-wear layer and an anti-wear layer outer side of the anti-wear layer facing away from the treatment element core are provided with a contour, and/or in which the anti-wear layer has a radial distance from the central longitudinal axis that varies along the central longitudinal axis, correspond to the advantages of the inventive method already described above.
A treatment element blank, in which the treatment element core is tubular, provides a simple way of producing and configuring different screw machines. The inner side of the treatment element core is provided with an inner profile in the usual manner, allowing differently designed treatment elements to be arranged on a profiled shaft which can be configured in a variable manner.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
In the drawings:
The following is a description of a first exemplary embodiment of the invention which is illustrated in
Production of a treatment element blank 10 in the pressing installation 1 is performed as follows:
In a first step, a treatment element core 11 of a first metal material M1 is arranged in the inner space 9 in such a way that the central longitudinal axis 12 thereof is substantially congruent with the central longitudinal axis 8. The front side of the treatment element core 11 abuts against the capsule bottom 6. The first material M1 shows a high degree of viscosity and ductility. Preferably, the first material M1 is steel. Afterwards, the capsule cover 7 is arranged on the capsule wall 5 and welded thereto. The front side of the capsule cover 7 abuts against the treatment element core 11.
The treatment element core 11 has a core outer side KA facing the annular space 14. The core outer side KA is contoured so as to form a core outer contour AK. Due to the core outer contour AK, the core outer side KA has a varying radial distance RKA from and along the central longitudinal axis 8 or 12, wherein said radial distance RKA varies between a minimum distance RKAmin and a maximum distance RKAmax.
The capsule wall 5 has a cylindrical capsule wall inner side W1, with the result that the capsule wall inner side W1 has a constant radial distance RW1 from the central longitudinal axis 8 or 12. Due to the constant radial distance RW1 and the varying distance RKA of the treatment element core 11, the annular space 14 is provided with a contour, having a thickness DR that varies along the central longitudinal axis 8 or 12, respectively, between a minimum thickness DRmin and a maximum thickness DRmax. The annular space 14 is completely filled with a powder of a second metal material M2 via the filler neck 13; afterwards, the filler neck 13 is closed. The powder 15 is required to form an anti-wear layer 16 surrounding the treatment element core 11. To this end, the second material M2 is a high-alloy material and therefore provides a high degree of wear-resistance and/or corrosion-resistance.
Afterwards, the treatment element blank 10 is produced in the pressing installation 1 by hot isostatic pressing so as to form a composite body of the first material M1 and the second material M2.
After hot isostatic pressing, the capsule 2 is removed by machining Due to the constant distance RW1, the treatment element blank 10 has a non-contoured cylindrical blank outer side RA. Correspondingly, the anti-wear layer 16 of the treatment element blank 10 has a constant radial distance RV from the central longitudinal axis 12 which corresponds to the distance RW1.
In a next step, the treatment element blank 10 is processed to form a treatment element 17. To this end, the treatment element blank 10 is formed by machining in such a way that a treatment element outer contour AB is produced. To this end, material areas 18 of the anti-wear layer 16 of the treatment element blank 10 are removed. The treatment element 17 is thus formed by said removal of material. The treatment element outer contour AB is formed by the anti-wear layer outer side VA. After the removal of material, the radial distance RVA varies along the central longitudinal axis 12 between a minimum distance RVAmin and a maximum distance RVAmax. Since both the core outer side KA, which corresponds to the anti-wear layer inner side V1, as well as the anti-wear layer outer side VA are provided with a contour, the anti-wear layer 16 of the treatment element 17 has a substantially constant thickness DV along the central longitudinal axis 12. Furthermore, an axial through-hole 20 is produced that is provided with an inner profile 19 for a profiled shaft. The through-hole 20 is preferably concentric to the central longitudinal axis 12. The blank outer side RA of the treatment element blank 10 is shown below the central longitudinal axis 12 in
Since the annular space 14 has a radial distance RKA that varies along the central longitudinal axis 12 because of the contoured core outer side KA, the anti-wear layer inner side V1 is provided with a contour as well, with the result that the quantity of the second material M2 required for the formation of the anti-wear layer 16 is comparatively reduced. After the removal of material, the anti-wear layer 16 also has a constant thickness DV in the material areas 18 which simplifies the subsequent heat treatment of the treatment element 14 while preventing the formation of stress cracks.
The following is a description of a second exemplary embodiment of the invention which is illustrated in
The treatment element blank 10a is produced in the manner already described above by arranging the treatment element core 11a in the capsule 2a of the pressing installation 1a and filling the annular space 14a with the powder 15. The treatment element blank 10a is produced by hot isostatic pressing. After hot isostatic pressing, the capsule 2a is removed by machining Since the capsule wall 5a is provided with a contour, the treatment element outer contour AB is already formed during the production of the treatment element blank 10a. Corresponding to the radial thickness DR of the annular space 14a, the radial thickness DV of the anti-wear layer 16 varies along the central longitudinal axis 12 between a minimum radial thickness DVmin and a maximum radial thickness DVmax. The treatment element blank 10a is already provided with a contoured anti-wear layer outer side VA. In order to produce the treatment element 17a, the anti-wear layer outer side VA only requires a small amount of fine machining
Afterwards, the treatment element 17a is provided with the through-hole 20 and the inner profile 19 for the profiled shaft in the usual manner and subjected to a heat treatment. The finished treatment element 17 is again shown at the top of
The following is a description of a third exemplary embodiment of the invention which is illustrated in
The capsule wall outer contour AW ensures that the treatment element blank 10 is already provided with the treatment element outer contour AB during production. If necessary, the treatment element outer contour AB is subjected to fine machining The core outer contour AK, which substantially corresponds to the treatment element outer contour AB, ensures that the anti-wear layer 16b thus formed has a radial thickness DV which is substantially constant. The constant thickness DV substantially prevents the formation of stress cracks, with the result that heat treatment of the treatment element 17b is simplified. The finished treatment element 17b is again shown at the top of
The following is a description of a fourth exemplary embodiment of the invention which is illustrated in
The following is a description of a fifth exemplary embodiment of the invention which is illustrated in
The following is a description of a sixth exemplary embodiment of the invention which is illustrated in
Corresponding to the sixth exemplary embodiment, the treatment element blanks 10a to 10d may be provided with the through-hole 20 during production already if the capsules 2a to 2d of the pressing installations 1a to 1d are configured corresponding to the capsule 2e and are provided with through-openings which correspond to the through-openings 21e.
The treatment elements 17, 17a to 17e and the corresponding treatment element blanks 10, 10a to 10e are in particular configured as screw and/or kneading elements and intended for use in screw machines, in particular twin-shaft screw machines for the treatment and processing of plastic materials. Materials suitable for the second material M2 are in particular those that allow a high degree of wear resistance and/or corrosion-resistance to be achieved. A suitable first material M1 is in particular a high-viscosity, ductile material such as steel. The production method according to the invention reduces the material quantity required for the second material M2. Heat treatment of the treatment elements 17, 17b, 17d, 17e is simplified since the anti-wear layer 16, 16b, 16d, 16e has a substantially constant radial thickness DV along the central longitudinal axis 12. Moreover, post-machining of the treatment elements 17a, 17b, 17c, 17d is simplified since the treatment element blank 10a, 10b, 10c, 10d is already produced in such a way as to be equipped with the treatment element outer contour AB. Generally speaking, the method according to the invention allows the production of treatment elements 17, 17a to 17e to be greatly simplified.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2011 080 255.8 | Aug 2011 | DE | national |
This application is a United States National Phase application of International Application PCT/EP2012/064932 filed Jul. 31, 2012 and claims the benefit of priority under 35 U.S.C. §119 of German patent application DE 10 2011 080 225.8 filed Aug. 1, 2011, the entire contents of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/064932 | 7/31/2012 | WO | 00 | 1/31/2014 |
