阅读说明：本技术 用于由弹性体制造成形体的增材制造方法 (Additive manufacturing method for manufacturing a shaped body from an elastomer ) 是由 S·考尔 S·施密特 B·安德斯 J·菲比格尔 D·比特纳 于 2020-04-20 设计创作，主要内容包括：本发明涉及用于制造由至少一层组成的的由非热塑性的弹性体材料(1)制成的成形体(100)的方法,包括下面的步骤：将高粘性的弹性体材料(1)输送至处理单元(2)；在处理单元(2)中处理弹性体材料(1)并且产生弹性体材料(1)的材料流；将弹性体材料(1)输送到存储单元(4)中并且在存储单元(4)中产生弹性体材料(1)的理论压力；将弹性体材料(1)输送至成形单元(5),在所述成形单元中,针对性地释放弹性体材料(1),以用于产生至少一层要形成的成形体(100)；通过交联单元(9)交联成形体(100)的所述至少一层或整个成形体(100)。(The invention relates to a method for producing a shaped body (100) made of a non-thermoplastic elastomer material (1) consisting of at least one layer, comprising the following steps: -conveying the elastomeric material (1) with high viscosity to a treatment unit (2); processing the elastomeric material (1) in a processing unit (2) and generating a material flow of the elastomeric material (1); feeding the elastomeric material (1) into a storage unit (4) and generating a theoretical pressure of the elastomeric material (1) in the storage unit (4); conveying the elastomer material (1) to a forming unit (5) in which the elastomer material (1) is released in a targeted manner for producing at least one layer of a formed body (100) to be formed; the at least one layer of the shaped body (100) or the entire shaped body (100) is crosslinked by the crosslinking unit (9).)

1. Method for manufacturing a shaped body (100) made of a non-thermoplastic elastomeric material (1) consisting of at least one layer, said method comprising the following steps:

a) -conveying the elastomeric material (1) to a treatment unit (2);

b) processing the elastomeric material (1) in a processing unit (2) and generating a material flow of the elastomeric material (1);

c) feeding the elastomeric material (1) into a storage unit (4) and creating a pre-pressure of the elastomeric material (1) in the storage unit (4);

d) conveying the elastomer material (1) to a forming unit (5) in which the elastomer material (1) is released in a targeted manner for producing at least one layer of a formed body (100) to be formed;

e) crosslinking the at least one layer of the shaped body (100) or the entire shaped body (100) by means of crosslinking units (9), wherein,

the elastomeric material (1) is highly viscous and crosslinkable during steps a) to d) and in particular has a viscosity in the range of 100 to 1000000Pa · s.

2. Method according to one of the preceding claims, characterized in that the elastomer material (1) is not curable and is elastic or viscoelastic.

3. Method according to one of the preceding claims, wherein the elastomeric material (1) is implemented as ACM, NBR, EPDM or HCR.

4. The process according to any one of the preceding claims, wherein the treatment of the elastomeric material (1) is carried out in step b) using one or more worms (3) and/or piston pumps and/or gear pumps and/or static mixers.

5. Method according to one of the preceding claims, wherein in step b) and/or in step d) the temperature of the elastomeric material (1) is controlled and adjusted to below 150 ℃, in particular below 90 ℃.

6. Method according to claim 5, characterized in that the treatment unit (2) and/or the forming unit (5) have a temperature-regulating device (8) for cooling and/or heating the elastomeric material (1).

7. Method according to one of the preceding claims, wherein in step d) the shaping unit (5) is implemented as a nozzle (6), in particular as a clocked nozzle.

8. Method according to one of the preceding claims, wherein the elastomeric material (1) is released in a sequential manner in step d).

9. A method according to claims 7 and 8, wherein the elastomeric material (1) is released in the form of beads.

10. A method according to claim 7, wherein the elastomeric material (1) has a shear velocity in the region of the nozzle (6) of 10 to 55001/s.

11. Method according to one of the preceding claims, wherein in steps d) and e) a relative movement between the forming unit (5) or the cross-linking unit (9) and the forming reception unit (7) is carried out for positioning the released elastomeric material (1) or for positioning the active area of the cross-linking unit (9).

12. Method according to one of the preceding claims, wherein steps d) and e) are repeated alternately in order to build up and cross-link the individual layers of the shaped body (100).

13. Method according to one of the preceding claims, comprising the additional step of

d') releasing the support material for creating the support area;

wherein steps d) and d') are performed alternately depending on the geometry of the shaped body (100) to be produced.

Technical Field

The invention relates to a method for producing a shaped body having the features of claim 1.

Background

Extrusion, metering and injection molding of elastomer molding compounds are used to a standard degree in the industry, for example for producing seals and membranes. The elastomer processed in the extruder is introduced into an injection mold by means of a nozzle. Small nozzles with an average channel diameter of 1 to 5mm are used here. The pressure loss in the nozzle is strongly dependent on the nozzle geometry and throughput as well as on the material viscosity.

It is also generally known and increasingly widely used to manufacture products from various materials in a so-called 3D printing process and in an additive manufacturing method. In this way, devices for the layered construction of products in additive manufacturing with thermoplastic materials are known. Such devices are described, for example, in DE 102009030099 a1, EP 1886793B 1 and EP 278274281B 1.

Disclosure of Invention

The object of the present invention is to specify a method for producing a shaped body, by means of which a shaped body can be produced from a non-thermoplastic elastomer material. It is a further object to be able to produce shaped bodies with a particularly fine structure with high precision by means of the method.

Technical solution

This object is achieved by a production method for producing shaped bodies having the features of claim 1.

According to the invention, it is recognized as advantageous to treat the non-thermoplastic elastomer material in an additive manufacturing process and to produce a shaped body there.

The method according to the invention is used as an additive manufacturing method for producing a three-dimensional shaped body consisting of at least one layer made of a non-thermoplastic elastomer material. That is, the material is a rubbery material with the exception of thermoplastic elastomers. The method has the following steps:

a) the treatment unit is fed with an elastomeric material as a raw material in the form of leather (i.e. a mat made of elastomeric material), strips, discs (i.e. discs made of elastomeric material) or strings.

b) The elastomeric material is processed in a processing unit and a material flow of the elastomeric material is generated. A defined viscosity of the elastomer material can also be produced and thermal and material homogenization can be carried out.

c) The elastomer material is fed into the storage unit and a pre-pressure of the elastomer material is generated in the storage unit. The pre-pressure is in this case in particular in the range below 600 bar and depends on the material being processed.

d) The elastomer material is conveyed to a forming unit, in which the elastomer material is released in a targeted manner for producing at least one layer of the formed body to be formed and thus for the layer-forming of the formed body. The elastomer material is conveyed here in particular with a mass flow in the range from 0.5 to 30 g/h.

e) Crosslinking the at least one layer of the shaped body or the entire shaped body by means of crosslinking units, wherein the crosslinking can be carried out thermally, optically or chemically.

The method steps a) to e) can be carried out in particular in a machine, a device for producing shaped bodies. Alternatively, the apparatus for producing the shaped body can be designed such that step e) can be carried out in separate, spaced-apart apparatuses, i.e. when the crosslinking of the entire shaped body is carried out.

The elastomeric material is a non-thermoplastic elastomeric material according to the Standard ASTM D1418-17 "Standard Practice for Rubber and Rubber latex-Nomenclature".

The technically interesting properties of non-thermoplastic elastomer materials are achieved firstly by compounding. Compounding is understood as adding defined additives, such as: fillers, aging inhibitors, softeners, processing aids, crosslinking chemicals, and the like. The type and amount of additive are directed to the respectively required characteristic curve of the material. In the crosslinking process, the so-called vulcanization, of the non-thermoplastic elastomer material, irreversible chemical crosslinking sites are formed.

These highly polymeric organic networks have high elasticity and can undergo large reversible deformations.

The elastomer material fed to the storage unit in step c) is a completely mixed material, to which no further material is added.

It is particularly preferred that the non-thermoplastic elastomeric material is a material made of chemically cross-linked rubber.

In the process according to the invention, the elastomeric material is highly viscous, i.e. not liquid, during steps a) to d) and may also be crosslinked. The elastomeric material in particular has a viscosity, i.e. a resistance to shear in the range of 100 to 1000000Pa · s. This results in a viscosity which is significantly higher than, for example, thermoplastics processed in injection molding processes.

It is surprising that such a process is carried out with non-thermoplastic elastomeric materials:

the calculation of the pressure loss of the material transported through the nozzle is described mainly in the specialist book "extrusion tools for plastics and rubbers (Extrusionswerkzeuge fur Kunststoffe und Kautschuke), Michaeli, second edition, chapter 2.1 and chapter 3.1".

The pressure loss calculation is based on the Hagen-Poiseuille law for laminar flow of incompressible viscous fluids through pipes:

Δ v ═ volumetric flow through the tube [ m ═ m³/s]

Δ p ═ the pressure difference between the beginning and the end of the tube [ Pa ]

r is the inner radius of the tube [ m ]

length of tube [ m ]

Eta. viscosity of flowing liquid [ pas ]

The usual calculations for manufacturing and, for example, metering chains with small diameters, with standard elastomer compounds and usual viscosities from the technical literature require very high pressures of about 700 to well over 10000 bar in order to achieve a mass flow of 0.5 to 30 g/h. However, such high pressures can only be produced with difficulty and are not practical. It has been surprisingly found that a lower pressure is also sufficient to allow the elastomeric material to be formed and released in the forming unit. This is because the actual pressure loss of the elastomeric material as it is conveyed through the forming unit, for example a fine nozzle, is significantly lower than that expected according to calculations common in the industry.

In a particularly advantageous and therefore preferred further development of the method, the elastomer material used is not curable and is here elastic or viscoelastic. I.e., the elastomeric material never assumes a solid phase, but retains its elastic or viscoelastic properties.

The elastomeric material may be, for example, a polyacrylate-rubber (ACM), a nitrile-butadiene rubber (NBR), an ethylene-propylene-rubber (EPDM) or a solid silicone rubber (high concentration rubber HCR).

In one possible embodiment of the method, the treatment of the elastomer material in step b) takes place using one or more worms and/or piston pumps and/or gear pumps and/or static mixers.

It has proven to be particularly advantageous to carry out the control and regulation of the temperature of the elastomeric material in step b) and/or step d) above 20 ℃ and below 150 ℃, in particular below 90 ℃ and below 35 ℃ in the case of HCR treatment. Premature crosslinking of the elastomeric material can thus be prevented. There is thereby a temperature which is significantly lower, for example compared to the thermoplastic processed in the injection molding process.

For this purpose, the treatment unit and/or the shaping unit can have a temperature control device for cooling and/or heating the elastomer material.

In a possible embodiment, the shaping unit can be embodied as a nozzle in step d), in particular as a clocked nozzle. Alternatively, open nozzles are also conceivable. The clocked nozzle has a blocking mechanism that can be actuated in a clocked manner, so that the elastomer material is alternately pressed through the nozzle and the nozzle is then blocked again. It has been shown to be particularly advantageous for the nozzle to have a diameter of less than 0.25 mm. This can result in shaped bodies having a particularly fine structure.

It has proven advantageous for the elastomeric material to have a shear rate in the region of the nozzle of from 10 to 55001/s. The pressure loss prevailing at this time is relatively small. Shear rate is also referred to as shear rate.

It has been found to be particularly advantageous that the elastomeric material is released in a sequential manner in step d) of the process. This means that the elastomer material is not released continuously, but rather a defined, definable amount of elastomer material is released, followed by a standstill in which no elastomer material is released. This can be achieved by using a clocked nozzle. The form of the sequence is distinguished here from a continuous form, for example a strip.

In a particularly advantageous and therefore preferred further development of the method, the elastomer material is released in the form of bead chains. The bead chain is characterized by the diameter of the beads being aligned with one another, i.e. changed by the bead shape on the strip. The diameter can vary here from 1 to 15%. Bead chains having an average diameter of 1mm or less, in particular 0.3mm or less, are preferred here.

The geometry and packing density of the bead chains can be adjusted and adapted by the clock frequency of the blocking mechanism of the clocked nozzle. It has been found that a particularly fine structure of the shaped bodies can be achieved by means of the bead chains. A further advantage results because the angle can be produced more simply in the shaped body than, for example, when the elastomer material is released in the form of a strip. It also advantageously appears that in a bead chain a tighter packing density of the elastomeric material in the shaped body can be achieved than in a strip.

In the method according to the invention, a relative movement between the shaping unit or the crosslinking unit and the shaping receptacle unit, i.e. the holder for the shaped body to be produced, can be carried out in steps d) and e) for positioning the released elastomer material or for positioning the active region of the crosslinking unit. The released elastomer material can thus be deposited in a targeted manner onto the shaped receiving unit or onto the elastomer layer already present there. Precision positioning systems capable of achieving multi-axis positioning and the relative motion required thereby are known to the academia.

In an advantageous variant of the method according to the invention, steps d) and e) are repeated alternately in order to build up and cross-link the layers of the shaped body before the respective next layer is applied.

In an advantageous variant of the method according to the invention, the release of the support material is carried out in an additional step for producing the support region, wherein the steps of releasing the elastomer material and releasing the support material are carried out alternately depending on the geometry of the shaped body to be produced. The support material then forms a support structure for the subsequently released layer of elastomeric material. The support material is selected such that it can be removed again in a simple manner. The support material may for example be water soluble or soluble in a lye which does not corrode the elastomeric material. This advantageously also results in shaped bodies with complex geometries.

The invention and the advantageous further configurations of the invention are also combined with one another, as long as they are technically suitable, to form the advantageous further configurations of the invention.

With regard to further advantages and advantageous embodiments of the invention with regard to structure and function, reference is made to the dependent claims and the description of the exemplary embodiments with reference to the figures. Examples

In the tests, the pressure loss was achieved in the following geometry, material and viscosity. The theoretical pressure loss is at a given significantly higher value:

shear rate

T temperature

Diameter of D nozzle

Length to diameter ratio of L/D nozzle

The pressure losses measured in the actual test sequence (hundreds of bars) in the other materials are significantly smaller than the calculated pressure losses (thousands of bars) in very fine nozzles with a diameter below 0.3 mm. That is, it can be confirmed by these test sequences that the elastomeric material can be extruded through a forming unit, for example a thin nozzle, and that in this way a form can be produced from the elastomeric material in an additive manufacturing method.

Drawings

The invention should be explained in more detail with the aid of the figures. For better clarity of the figure, the display with faithful scale is abandoned.

Shown in the schematic diagram:

fig. 1 shows an apparatus for manufacturing a shaped body in an additive manufacturing method.

Detailed Description

In the figure, an apparatus 10 for producing a shaped body 100 is shown, in which apparatus the shaped body 100 is produced from an elastomer material 1 in an additive manufacturing method. For this purpose, the elastomer material 1 is fed to a processing unit 2 and processed there by means of a worm 3.

The elastomeric material 1 thus treated is fed to a storage unit 4, through which it is supplied to a forming unit 5 comprising a nozzle 6. The shaping receptacle unit 7 is arranged below the nozzle 6 and is freely movable. The elastomer material 1 discharged from the nozzle 6 is stored on the forming-receiving unit, and thus the formed body 100 is constituted. A cross-linking unit 9 is arranged near the nozzle 6 and is used for cross-linking of the layer of elastomeric material 1. The treatment unit 2 and the forming unit 5 may be provided with a temperature regulating device 8, respectively, for regulating the temperature of the elastomeric material 1 in the treatment unit 2 and the forming unit 5.

In an alternative embodiment, which is not shown, the nozzle 6 and possibly the crosslinking unit 9 are also moved relative to the shaping receptacle unit 7.

It is also possible for the crosslinking unit 9 to be provided separately and at a distance from the other components of the apparatus 10, i.e. when the entire shaped body 100 as a whole should be crosslinked.

The method according to the invention can be carried out using an apparatus 10 for producing shaped bodies 100.

In a first step, the transfer of the elastomeric material 1 to the treatment unit 2 is carried out. In the treatment unit 2, the treatment of the elastomeric material 1 is carried out and a material flow of the elastomeric material 1 is generated. The processing of the elastomeric material 1 takes place using a worm 3 which conveys the elastomeric material 1 into a storage unit 4, where a pre-pressure is created which is sufficient for releasing the elastomeric material 1 by a forming unit 5. In the forming unit 5, which is configured as a rhythmic nozzle 6, the elastomer material 1 is discharged in a targeted manner in the form of a chain of beads. The layers of shaped bodies 100 to be formed are stored on the shaping receptacle unit 7. The treatment unit 2 and the forming unit 5 have a tempering device 8 for cooling and/or heating the elastomeric material 1, so as to perform a control and regulation of the temperature of the elastomeric material 1 above 20 ℃ and below 150 ℃. Premature crosslinking of the elastomeric material can thus be prevented.

The crosslinking of the at least one layer of shaped body 100 is carried out in a next step by means of crosslinking units 9. The release of the elastomeric material 1 and the cross-linking of the layers are repeated alternately in order to build up and cross-link the various layers of the shaped body 100 until the shaped body 100 is completed.

Relative movement between the forming unit 5 and the forming receiving unit 7 can be achieved as indicated by the double arrow for positioning of the released elastomeric material 1.

As indicated by the double arrow, a relative movement between the cross-linking unit 9 and the form-receiving unit 7 can also be achieved for positioning the region of action of the cross-linking unit 9.

In an alternative embodiment of the method, which is not shown, the nozzle 6 and possibly the crosslinking unit 9 are moved relative to the forming-receiving unit 7.

It is also possible for the crosslinking unit 9 to be provided separately and at a distance from the other components of the apparatus 10, i.e. when the entire shaped body 100 as a whole should be crosslinked. The transportation of the shaped body 100 to the crosslinking unit 9 is then carried out between the step of "releasing the elastomeric material 1" for constituting the shaped body and the step of "crosslinking".

List of reference numerals

1. Elastomeric material

2. Processing unit

3. Worm screw

4. Memory cell

5. Forming unit

6. Nozzle with a nozzle body

7. Shaped receiving unit

8. Temperature control device

9. Crosslinking unit

10. Device for producing shaped bodies

100. Formed body