DE102020125537A1 - Process for manufacturing an extruder barrel - Google Patents

Abstract

Method for producing an extruder barrel (1), the extruder barrel (1) comprising a receiving space (2) delimited by at least one wall (3) for receiving an extruder screw, comprising the steps of:- providing at least one extruder barrel (1), the extruder barrel (1) comprises a receiving space (2) delimited by at least one wall (3) for receiving an extruder screw,- carrying out at least one measure to influence the surface properties of the at least one wall (3) delimiting the receiving space (2), the measure comprising at least one thermally induced diffusion process for diffusing at least one diffusion element into the surface of the at least one wall (3).

Description

The invention relates to a method for producing an extruder barrel, the extruder barrel comprising a receiving space delimited by at least one wall for receiving an extruder screw.

Methods for producing corresponding extruder barrels, which usually comprise a receiving space delimited by at least one wall for receiving an extruder screw, are basically known in various designs from the prior art.

Since the corresponding extruder cylinders are typically components that are used during operation of an extrusion device, i. H. in the context of processing extrudable plastic materials, special stresses, such as e.g. B. abrasion, corrosion, wear, etc., there is a need for practicable principles, which can be used to produce extruder barrels in an efficient and reliable manner with improved properties.

Proceeding from this, the invention is based on the object of specifying an improved method for producing an extruder barrel with improved properties.

The object is achieved by a method for producing an extruder barrel according to claim 1. The claims dependent on this relate to possible embodiments of the method.

A first aspect of the invention relates to a method for producing an extruder barrel. The extruder cylinder comprises a receiving space, in particular cylindrical, delimited by at least one wall, for receiving an extruder screw. During operation of the extruder barrel, the receiving space is typically used equally to melt extrudable plastic material, which is typically supplied in the form of granules to the extruder barrel or to a higher-level extrusion device that encompasses it. The recording space can be divided into several functionally different zones; In particular, the receiving space can be divided into a feed zone, a compression zone and a metering zone.

In a first step of the process, at least one corresponding extruder barrel, i. H. an extruder cylinder, which comprises a receiving space delimited by at least one wall, in particular cylindrical, for receiving an extruder screw.

At least in the region of the wall(s) delimiting the receiving space, the extruder cylinder is formed from a starting material or base material which is formed by thermochemical processes, i. H. in particular thermochemical diffusion processes, in its properties, d. H. especially in its mechanical as well as in its thermal properties can be modified. For example, the extruder barrel can be made of an iron-based material or material, such as e.g. B. a steel, further in particular a non-alloyed or a low-alloyed steel. According to the method, an extruder cylinder with a wall delimiting the receiving space made of an iron-based base material, in particular a steel, more particularly a non-alloyed or a low-alloyed steel, can therefore be used. Of course, the entire extruder cylinder can also be formed from a corresponding starting or base material.

In a second step of the method, at least one measure is carried out to influence the surface properties of the at least one wall delimiting the receiving space, the measure including at least one thermally induced diffusion process for diffusing at least one diffusion element into the surface of the at least one wall. In the second step of the method, at least one measure is therefore carried out by means of which the properties, i. H. in particular the mechanical and/or thermal properties, more particularly the thermomechanical properties, and/or the tribological properties and/or the corrosion properties and/or the oxidation properties, of the at least one wall are specifically modified. In this way, edge layers with modified or improved properties compared to other areas of the respective wall(s) or to other areas of the extruder barrel, i. H. in particular with improved abrasion, corrosion and/or oxidation and/or wear properties. The specific properties of correspondingly modified surface layers are essentially determined by the parameters specified in more detail below, such as e.g. B. Duration, temperature, etc., which are applied in the context of carrying out the at least one measure.

The at least one measure includes at least one thermally induced diffusion process for diffusing at least one diffusion element, ie, for example aluminum or boron or chromium or silicon or vanadium, into the surface of the at least one wall; the least one measure therefore results in diffusion processes and thus in diffusion of at least one diffusion element into the surface of the at least one wall. The respective diffusion element can in particular diffuse into the lattice structure of the starting material or base material forming the at least one wall—this is, as mentioned, typically an iron-based material—and thus modify the properties.

Typically, the at least one measure is carried out in such a way that the diffusion element or elements diffuse in exclusively in the area of the wall(s) delimiting the receiving space. Consequently, there is typically a local modification of the properties of the extruder barrel only in the region of the wall(s) delimiting the receiving space and thus only in the region of the extruder barrel which is subject to particular stresses during operation, such as e.g. B. abrasion, corrosion, wear, etc., is exposed. This represents an extremely efficient approach to making an extruder barrel.

Overall, there is therefore an improved method for producing an extruder barrel with improved properties.

As mentioned, the at least one measure can include the formation of a modified surface layer compared to an original surface layer of the at least one wall, in particular with regard to its chemical composition, or the formation of a surface layer of the at least one wall compared to an original surface layer Wall, in particular with regard to their chemical composition, modified surface layer result. As also mentioned, a correspondingly modified surface layer is characterized by improved properties compared to the original surface layer.

The at least one measure can be carried out at a temperature from a range between 700 and 1300°C, in particular between 750 and 1250°C, more particularly between 800 and 1200°C. The specifically selected temperature is typically determined by the respective diffusion element, which is intended to diffuse into the starting or base material as part of carrying out the measure, i. H. generally according to the thermochemical process on which the measure actually carried out is based. In principle, as indicated above, modified surface layers can be formed via the process parameters used in the course of carrying out the measure; it is therefore conceivable that the influence of temperature, e.g. B. on the penetration depth and / or the concentration of the respective diffusion element and thus generally influence on the specific properties of the modified surface layer can be taken.

The at least one measure can be carried out for a period of between 10 and 50 hours, in particular between 20 and 40 hours, more particularly for 30 hours. The specifically selected duration is typically determined by the particular diffusion element which is to diffuse into the starting or base material as part of carrying out the measure, i. H. generally according to the thermochemical process on which the measure actually carried out is based. In principle, as indicated above, modified surface layers can be formed via the process parameters used in the course of carrying out the measure; it is therefore conceivable that (also) over the long term influence e.g. B. on the penetration depth and / or the concentration of the respective diffusion element and thus generally influence on the specific properties of the modified surface layer can be taken.

As mentioned, the at least one measure results in at least one diffusion element diffusing into the surface of the at least one wall, with the respective diffusion element being incorporated into the lattice structure of the starting material or base material forming the at least one wall—this is, as mentioned, typically around an iron-based material - can diffuse in and thus modify the properties. In particular, the at least one measure can include the formation of mixed crystals or compounds of the starting material or base material of the at least one wall with the at least one diffusion element or in a formation of mixed crystals or compounds of the starting material or base material of the at least one wall with the at least one Diffusion element result. The formation of corresponding mixed crystals or corresponding compounds can result in the special properties of the respective modified surface layer.

In all embodiments of the method, the at least one measure can include applying a composition containing the at least one diffusion element or a compound containing the at least one diffusion element, in particular gaseous, liquid, viscous or solid, to the at least one wall. The method can therefore, after the provision of the at least one extruder cylinder, initially include a first partial step of applying the at least one diffusion element or a compound containing the at least one diffusion element, possibly also to be referred to or to be considered as a dispensing agent, on the at least one wall and then as a second sub-step the temperature control of the respective wall or the extruder cylinder required for initiating corresponding diffusion processes. A corresponding composition containing at least one diffusion element can be gaseous, liquid, pasty or viscous or solid; with a corresponding composition it can be z. B. to a gas, a liquid, a paste, a gel or a solid such. B. a granulate or a powder act. Depending on its original state of aggregation, the respective composition can undergo a phase change during tempering.

As mentioned, z. B. aluminum, boron, chromium, silicon, vanadium can be used as a diffusion element. According to the method, at least one diffusion element from the group: aluminum, boron, chromium, silicon, vanadium can be used. The at least one measure can therefore specifically include aluminizing, boriding, chroming or inchroming, or siliconizing, or vanadizing.

As mentioned, the at least one measure results in a modified surface layer with improved properties. The improved properties of the modified surface layer can be based on an improved hardness compared to the starting or base material. The at least one measure can, depending on the diffusion element, e.g. B. result in a modified surface layer with a hardness in a range between 700 and 3250 HV, in particular between 750 and 3000 HV. Depending on the diffusion element used, the aforementioned hardness values are typically up to a temperature of at least 500° C., optionally at least 600° C., further optionally at least 700° C., further optionally at least 800° C., further optionally at least 800° C, further optionally of at least 900°C, further optionally of at least 1000°C, further optionally of at least 1100°C; so that the at least one measure typically results in a modified surface layer with a high temperature stability.

Concrete examples of embodiments of the method are given below in a non-exhaustive list.

According to a first example, an aluminum-containing composition (dispenser), such as e.g. B. Al-Si-Fe, z. B. in the form of granules or powder applied. The application can also take place by introducing the extruder barrel into a bath of a corresponding composition. This is followed by tempering to a temperature in a range between 800 and 1100° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). In this respect, the measure represents aluminizing. In this way, a modified surface layer with aluminum mixed crystals and/or aluminum oxide (Al ₂ O ₃ ) compounds can be formed, which has a hardness of approx. 2000 HV even at temperatures above 500°C and generally provides protection for low-carbon feedstock or base materials. The modified surface layer can have a layer thickness resulting from the penetration depth in a range between 0.1 and 0.3 mm.

According to a second example, a boron-containing composition (dispenser), such as e.g. B. B ₄ C or KBF ₄ , z. B. applied in the form of granules or powder or a paste. This is followed by tempering to a temperature in a range between 800 and 1100° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). In this respect, the measure represents boriding. In this way, a modified surface layer with iron boride (Fe ₂ B / FeB) compounds can be formed, which has a hardness of approx. 2000 HV even at temperatures above 500°C and generally has improved abrasion resistance. and tribooxidative properties are formed. The modified surface layer can have a layer thickness resulting from the penetration depth in a range between 0.1 and 0.3 mm.

According to a third example, a silicon-containing composition (dispenser), such as e.g. B. Si-Cl, e.g. B. in the form of granules or powder or in particular a gas applied. For this purpose, the extruder cylinder can B. be stored in an atmosphere containing a corresponding gas. This is followed by tempering to a temperature in a range between 950 and 1000° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). To this extent, the measure represents a silicization. In this way, a modifi adorned edge layer with pure silicon and/or iron silicide (Fe ₂ Si ₂ ) compounds are formed, which has a hardness of approx. 1300 HV even at temperatures above 500° C. and generally offers improved abrasion properties and improved thermomechanical stability will. The modified surface layer can have a layer thickness resulting from the penetration depth in a range between 0.1 and 0.3 mm.

According to a fourth example, a chromium-containing composition (dispenser), such as e.g. e.g. CrCl ₂ , e.g. B. in the form of granules or powder applied. This is followed by tempering to a temperature in a range between 950 and 1200° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). In this respect, the measure represents chroming (chroming). In this way, a modified surface layer with iron-chromium solid solution compounds can be formed, which has a hardness of approx. 2000 HV even at temperatures above 500°C and generally offers improved corrosion properties , to be formed. The modified surface layer can have a layer thickness resulting from the penetration depth in a range between 0.1 and 0.3 mm.

According to a fifth example, a vanadium-containing composition (dispenser), such as e.g. B. vanadium oxide (V ₂ O ₅ ), z. B. in the form of granules or powder applied. This is followed by tempering to a temperature in a range between 1000 and 1100° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). In this respect, the measure represents vanadizing. In this way, a modified surface layer with vanadium carbide (VC/V ₂ C) compounds can be formed, which has a hardness of approx. 3000 HV even at temperatures above 500° C. and generally offers improved abrasion properties , to be formed. The modified surface layer can have a layer thickness resulting from the penetration depth in a range between 0.1 and 0.3 mm.

For all of the aforementioned examples, activators can also be used in addition to the respective dispensing agents, which promote the respective diffusion process.

Individual, several or all of the above examples can also, for. B. be combined by staggered sequence.

For all embodiments of the method, after the at least one measure, at least one further measure for influencing the mechanical properties of the at least one wall, in particular the at least one modified surface layer, can be carried out. The mechanical properties of the extruder cylinder can therefore be adjusted in a targeted manner after the production of appropriately modified surface layers. In a corresponding further measure, it can be z. B. to a heat treatment such. B. tempering, carburizing, martensitic hardening, etc. act.

A second aspect of the invention relates to an extruder barrel for an extrusion device for processing extrudable plastic material. The extruder barrel was produced according to the method according to the first aspect of the invention and is therefore distinguished by a modified outer layer with special properties. All statements in connection with the method according to the first aspect of the invention apply analogously to the extruder barrel according to the second aspect of the invention and vice versa.

With regard to its geometric dimensions, the extruder cylinder can be designed to be comparatively compact. For example, the extruder barrel can have a diameter in a range between 30 and 50 mm and based thereon a length-to-diameter ratio (L/D ratio) of 10-30, in particular 15. The method is therefore particularly suitable for modifying the properties of the wall(s) delimiting a respective receiving space in correspondingly compact extruder cylinders.

A third aspect of the invention relates to an extrusion device with an extruder cylinder according to the second aspect of the invention. All statements made in connection with the method according to the first aspect of the invention therefore also apply analogously to the extrusion device according to the third aspect of the invention. In addition to the extruder cylinder, the extrusion device typically also includes an extruder screw accommodated in the receiving space of the extruder cylinder and a drive device, in particular a motor, assigned to the extruder screw.

The extrusion device can for extrusion-based production of at least one dreidi dimensional object (not shown), such as B. a technical component or a technical component group set up. The extrusion-based production of a three-dimensional object by means of the extrusion device can therefore be carried out at least in sections, optionally completely, in layers.

• 1 ein Flussdiagramm eines Verfahrens gemäß einem Ausführungsbeispiel der Erfindung;
• 2 eine Prinzipdarstellung eines Extruderzylinders gemäß einem Ausführungsbeispiel der Erfindung; und
• 3 eine vergrößerte Ansicht einer modifizierten Randschicht gemäß einem Ausführungsbeispiel der Erfindung.

Further advantages, features and details of the invention result from the following description of the drawings; shows:

• 1 a flowchart of a method according to an embodiment of the invention;
• 2 a schematic diagram of an extruder cylinder according to an embodiment of the invention; and
• 3 an enlarged view of a modified surface layer according to an embodiment of the invention.

1 shows a flowchart of a method according to an embodiment of the invention.

The method is used to produce an extruder barrel 1, as z. Am 2 shown in a perspective view. As follows, the method can also be referred to or considered as a method for producing a modified surface layer in the area of a wall 3 delimiting a receiving space 2 of an extruder cylinder 1 .

Based on 2 it can be seen that a corresponding extruder cylinder 1 comprises a, in particular cylindrical, receiving space 2 delimited by one or more wall(s) 3 for receiving an extruder screw (not shown). When the extruder cylinder 1 is in operation, the receiving space 2 serves to melt extrudable plastic material, which is typically supplied in the form of granules to the extruder cylinder 1 or to a higher-level extrusion device (not shown) surrounding it. The receiving space 2 can be divided into several functionally different zones; In particular, the receiving space 2 can be divided into a feed zone, a compression zone and a metering zone.

Referring to the flow chart in 1 In a first step S1 of the method, at least one corresponding extruder barrel 1, ie an extruder barrel 1, which comprises a receiving space 2 delimited by one or more wall(s) 3 for receiving an extruder screw, is provided.

The extruder cylinder 1 is formed, at least in the area of the wall(s) 3 delimiting the receiving space 2, from a starting material or base material which, as a result of thermochemical processes, i.e. in particular thermochemical diffusion processes, is characterized in terms of its properties, i.e. in particular its mechanical as well as its thermal properties properties, can be modified. in the in 2 The exemplary embodiment shown is the extruder cylinder 1, at least in the area of the wall(s) 2 delimiting the receiving space 2, for example made of an iron-based material or substance, such as, for example, iron. B. a steel, further in particular a non-alloyed or a low-alloyed steel formed. According to the method, an extruder cylinder 1 made of an iron-based starting material or base material, in particular a steel, more particularly a non-alloyed or a low-alloyed steel, can therefore be used.

In a second step S2 of the method, at least one measure is carried out to influence the surface properties of the wall(s) 3 delimiting the receiving space 2, the measure including at least one thermally induced diffusion process for diffusing at least one diffusion element into the surface of the wall(s) 3 contains. In the second step S2 of the method, at least one measure is therefore carried out by means of which the properties, ie in particular the mechanical and/or thermal properties, further in particular the thermomechanical properties, and/or the tribological properties and/or the corrosion properties and/or the Oxidation properties, the wall (s) 3 are specifically modified. In this way, edge layers 4 (cf. 3 ) with compared to other areas of the extruder barrel 1 modified or improved properties, ie in particular with improved abrasion, corrosion and / or oxidation and / or wear properties. The specific properties of corresponding modified edge layers 4 are essentially determined by the parameters specified in more detail below, such as e.g. B. Duration, temperature, etc., which are used in the implementation of the respective measure.

The measure includes at least one thermally induced diffusion process for diffusing at least one diffusion element, ie, for example, aluminum or boron or chromium or silicon or vanadium, into the surface of the wall(s) 3; the measure therefore results in diffusion processes and thus a diffusing of at least one diffusion element into the surface of the wall(s) 3. The respective diffusion element can in particular in the lattice structure of the wall (en) 3 forming starting or base material - this is, as mentioned, an iron-based material - diffuse in and thus modify the properties.

The measure is carried out in such a way that the diffusion element or elements diffuse in only in the region of the wall(s) 3 delimiting the receiving space 2 . Consequently, there is a local modification of the properties of the extruder barrel 1 only in the area of the wall(s) 3 delimiting the receiving space 2 and thus only in the area of the extruder barrel 1 which is subject to special stresses during operation, such as e.g. B. abrasion, corrosion, wear, etc., is exposed.

As mentioned, the measure includes the formation of a surface layer 4 that is modified compared to the original surface layer of the wall(s) 3, in particular with regard to its chemical composition, or results in the formation of a surface layer of the wall that is compared to an original surface layer (en) 3, in particular with regard to its chemical composition, modified surface layer 4. As also mentioned, a correspondingly modified surface layer 4 is characterized by improved properties compared to the original surface layer.

The measure can be carried out at a temperature from a range between 700 and 1300°C, in particular between 750 and 1250°C, more particularly between 800 and 1200°C. The specifically selected temperature is typically determined by the respective diffusion element, which is intended to diffuse into the starting or base material as part of carrying out the measure, i. H. generally according to the thermochemical process on which the measure actually carried out is based.

The at least one measure can be carried out for a period of between 10 and 50 hours, in particular between 20 and 40 hours, more particularly for 30 hours. The specifically selected duration is typically determined by the particular diffusion element which is to diffuse into the starting or base material as part of carrying out the measure, i. H. generally according to the thermochemical process on which the measure actually carried out is based.

As mentioned, the at least one measure results in at least one diffusion element diffusing into the surface of the wall(s) 3, with the respective diffusion element diffusing into the lattice structure of the starting or base material forming the wall(s) 3 and thus modifying the properties can. The measure can include the formation of mixed crystals or compounds of the starting or base material of the wall(s) 3 with the at least one diffusion element or in a formation of mixed crystals or compounds of the starting or base material of the wall(s) 3 with the at least one diffusion element result. The formation of corresponding mixed crystals or corresponding compounds can result in the special properties of the respective modified surface layer 4.

Coming back the flowchart in 1 , it can be seen that the measure can include the application of a composition containing at least one diffusion element or a compound containing at least one diffusion element, in particular gaseous, liquid, viscous or solid, to the wall(s). After the extruder barrel 1 has been made available, the method can therefore initially include a first sub-step S2.1 of applying a composition containing the at least one diffusion element or a compound containing the at least one diffusion element, optionally also to be designated or considered as a dispensing agent the wall(s) 3 and then, as a second partial step S.2.2, the temperature control of the respective wall(s) 3 or the extruder cylinder 1 required for initiating corresponding diffusion processes. A corresponding composition containing at least one diffusion element can be gaseous, liquid, pasty or viscous or solid; with a corresponding composition it can be z. B. to a gas, a liquid, a paste, a gel or a solid such. B. a granulate or a powder act. Depending on its original state of aggregation, the respective composition can undergo a phase change during tempering.

The improved properties of the modified surface layer 4 can be based on or result from an improved hardness compared to the starting or base material. The measure can, depending on the diffusion element z. B. result in a modified surface layer with a hardness in a range between 700 and 3250 HV, in particular between 750 and 3000 HV. Depending on the diffusion element used, the aforementioned hardness values are typically up to a temperature of at least 500° C., optionally at least 600° C., further optionally at least 700° C., further optionally at least 800° C., further optionally at least 800° C, further optionally of at least 900°C, further optionally of at least 1000°C, further optionally of at least 1100°C; so that the measure typically results in a modified surface layer 4 with high temperature stability.

Concrete exemplary embodiments of the method are given below in a non-exhaustive list.

According to a first exemplary embodiment, an aluminum-containing composition (dispenser), such as e.g. B. Al-Si-Fe, z. B. in the form of granules or powder applied. This is followed by tempering to a temperature in a range between 800 and 1100° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). In this respect, the measure represents aluminizing. In this way, a modified surface layer 4 with aluminum mixed crystals and/or aluminum oxide (Al ₂ O ₃ ) compounds can be formed, which has a hardness of approx. 2000 HV even at temperatures above 500°C and generally provides protection for low-carbon feedstocks. The modified edge layer 4 can have a layer thickness d, which results from the penetration depth, in a range between 0.1 and 0.3 mm.

According to a second example, a boron-containing composition (dispenser), such as e.g. B. B ₄ C or KBF ₄ , z. B. applied in the form of granules or powder or a paste. This is followed by tempering to a temperature in a range between 800 and 1100° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). In this respect, the measure represents boriding. In this way, a modified surface layer 4 with iron boride (Fe ₂ B/FeB) compounds can be formed, which has a hardness of approx. 2000 HV even at temperatures above 500° C. and generally improved abrasion - and tribooxidative properties are formed. The modified edge layer 4 can have a layer thickness d, which results from the penetration depth, in a range between 0.1 and 0.3 mm.

According to a third example, a silicon-containing composition (dispenser), such as e.g. B. Si-Cl, e.g. B. in the form of granules or powder or in particular a gas applied. The extruder barrel 1 can do this, for. B. be stored in an atmosphere containing a corresponding gas. This is followed by tempering to a temperature in a range between 950 and 1000° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). In this respect, the measure represents siliconizing. In this way, a modified surface layer 4 with pure silicon and/or iron silicide (Fe ₂ Si ₂ ) compounds can be formed, which has a hardness of approx. 1300 HV even at temperatures above 500° C generally offers improved abrasion properties as well as improved thermomechanical stability. The modified edge layer 4 can have a layer thickness d, which results from the penetration depth, in a range between 0.1 and 0.3 mm.

According to a fourth example, a chromium-containing composition (dispenser), such as e.g. e.g. CrCl ₂ , e.g. B. in the form of granules or powder applied. This is followed by tempering to a temperature in a range between 950 and 1200° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). In this respect, the measure represents chroming (chroming).

In this way, a modified surface layer 4 with iron-chromium mixed-crystal compounds can be formed, which has a hardness of approximately 2000 HV even at temperatures above 500° C. and generally offers improved corrosion properties. The modified edge layer 4 can have a layer thickness d, which results from the penetration depth, in a range between 0.1 and 0.3 mm.

According to a fifth example, a composition containing vanadium (dispenser), such as e.g. B. vanadium oxide (V ₂ O ₅ ), z. B. in the form of granules or powder applied. This is followed by tempering to a temperature in a range between 1000 and 1100° C. for a period of 30 h (temperature and duration can, as mentioned, vary in principle depending on the desired penetration depth or concentration). In this respect, the measure represents vanadium. In this way, a modified surface layer 4 with vanadium carbide (VC/V ₂ C) compounds can be formed, which also has a hardness of approx. 3000 HV at temperatures above 500°C and generally offers improved abrasion properties. The modified edge layer 4 can have a layer thickness d, which results from the penetration depth, in a range between 0.1 and 0.3 mm.

For all of the aforementioned exemplary embodiments, in addition to the respective dispensing means, activators can also be used, which promote the respective diffusion process.

Individual, several or all of the above examples can also, for. B. be combined by staggered sequence.

In 1 It is also indicated that after the measure, ie after step S2, optionally at least one further measure, cf. step S3, can be carried out to influence the mechanical properties of the wall(s) 3. The mechanical properties of the extruder cylinder 1 can thus be adjusted in a targeted manner after the production of correspondingly modified edge layers 4 . In a corresponding further measure, it can be z. B. to a heat treatment such. B. tempering, carburizing, martensitic hardening, etc. act.

In connection with the extruder cylinder 1 that can be produced or produced according to the method, it applies that it can be made comparatively compact with regard to its geometric dimensions. For example, the extruder barrel 1 can have a diameter in a range between 30 and 50 mm and based thereon a length-to-diameter ratio (L/D ratio) of 10-30, in particular 15. The method is therefore particularly suitable for modifying the properties of the wall(s) 3 delimiting a respective receiving space 2 in a correspondingly compact extruder cylinder 1.

Claims (12)

Method for producing an extruder barrel (1), the extruder barrel (1) comprising a receiving space (2) delimited by at least one wall (3) for receiving an extruder screw, characterized by the steps of: - providing at least one extruder barrel (1), the extruder cylinder (1) comprises a receiving space (2) delimited by at least one wall (3) for receiving an extruder screw, - carrying out at least one measure to influence the surface properties of the at least one wall (3) delimiting the receiving space (2), the measure at least includes a thermally induced diffusion process for diffusing at least one diffusion element into the surface of the at least one wall (3). procedure after claim 1 , characterized in that the at least one measure includes the formation in a compared to an original surface layer of the at least one wall (3), in particular with regard to its chemical composition, modified surface layer (4) or in the formation in a compared to an original surface layer of the at least one wall (3), modified surface layer (4), in particular with regard to its chemical composition. procedure after claim 1 or 2 , characterized in that the measure is carried out at a temperature from a range between 700 and 1300°C, in particular between 750 and 1250°C, more particularly between 800 and 1200°C. Method according to one of the preceding claims, characterized in that the measure is carried out for a period of between 10 and 50 hours, in particular between 20 and 40 hours, more particularly 30 hours. Method according to one of the preceding claims, characterized in that the at least one measure includes the formation of mixed crystals or compounds of the starting or base material of the at least one wall (3) with the at least one diffusion element or in a formation of mixed crystals or compounds of the Starting material or base material of the at least one wall (3) with the at least one diffusion element results. Method according to one of the preceding claims, characterized in that the at least one measure comprises applying a composition containing the at least one diffusion element or a compound containing the at least one diffusion element, in particular gaseous, liquid, viscous or solid, to the at least one wall (3) contains. Method according to one of the preceding claims, characterized in that at least one element selected from the group: aluminium, boron, chromium, silicon, vanadium is used as the diffusion element. Method according to one of the preceding claims, characterized in that the at least one measure results in a modified surface layer (4) with a hardness in a range between 700 and 3250 HV, in particular between 750 and 3000 HV. Method according to one of the preceding claims, characterized in that after the at least one measure at least one further measure for influencing the mechanical properties of the at least one wall (3), in particular the at least one modified edge layer (4), is carried out. Method according to one of the preceding claims, characterized in that an extruder cylinder (1) with a wall made of an iron-based starting material or base material, in particular a steel, more particularly a non-alloyed or a low-alloyed steel, is used. Extruder barrel (1) manufactured according to a method according to any one of the preceding claims. Extrusion device for processing plastic material for the extrusion-based production of at least one three-dimensional object, comprising at least one extruder cylinder (1). claim 11 .

Images