METHOD AND DEVICE FOR PRODUCING A STRUCTURED PRODUCT

Description

[0001] The invention relates to a method and a device for producing a strand material.

[0002] In this context, extruded material refers to stretched components that are produced, in particular, as continuous products using an extrusion process. Extruded material refers, in particular, to (electrical) cables and hoses. In both cases, the extruded material has an (outer) sheath formed by the aforementioned extrusion process.

[0003] The stranded material generally has a core to which the sheath is applied. In the case of a hose, for example, the core has a hollow space. In the case of a cable, the core is a cable core with at least one electrical conductor. Depending on the cable type, the cable core can have a wide variety of structures. Molded parts such as connector housings, grommets, seals, or combinations thereof are often attached to the cable.

[0004] Hoses are typically constructed in multiple layers, with the outermost layer forming the jacket described above. This is then applied to a hose core consisting of a multi-layer structure. The hose core is typically hollow. Such a hose is also used, for example, to route electrical cables or lines within the hollow space or to conduct fluids. Molded parts are also attached to the hose jacket, for example, in a connection area.

[0005] The applicant's subsequently published PCT / EP 2016 / 061426 describes a method for producing such a strand material, in which a respective shaped element is formed from the still-formable material of the shell using a molding unit immediately downstream of an extrusion unit. For this purpose, the molding unit, which has two mold halves designed as mold cavities, is advanced in a radial direction, and then, by scraping off a portion of the shell material, the material is accumulated, so that the mold cavities are filled with the material to form the molded part.

[0006] With regard to a continuous process, rotary concepts are provided in which the mold cavities are moved in a rotating manner, for example on a disc or by means of a rotating belt.

[0007] US 2015 / 0217708 A1 describes a rotary concept in which a large number of individual mold blocks are lined up on a rotating belt to produce a corrugated tube for cable sheathing. The speed of the belt can be varied depending on whether areas are to be formed with more or less material.

[0008] DE 198 45 321 A1 also describes a circular concept, but in this case vacuum elements are provided for shaping.

[0009] Further examples of circular concepts specifically for the formation of corrugated pipes can be found, for example, in JP 2014 218028 A or US 3 881 851 A.

[0010] In general, it has been shown that, due to the buildup of material during the forming process, considerable pressure is exerted, creating the risk of the individual mold halves being forced apart. To solve this problem, a counterpressure device, specifically a counterpressure plate, could be designed and arranged. This counterpressure exerts (additional) counterpressure on the forming unit in the direction of the extruded material during the forming process, reliably holding it in the desired position relative to the extruded material during the forming process.

[0011] In general, the aim is to integrate such a forming process for the formation of shaped parts into a conventional extrusion process with the usual extrusion speeds in order to enable a usual line speed in the production of the extruded material.

[0012] Based on this, the invention is based on the object of enabling the formation of a strand material with a molded part in a process-reliable manner and at high speed.

[0013] The object is achieved according to the invention by a method having the features of claim 1 and by a device having the features of claim 14. Preferred embodiments are set forth in the subclaims. The advantages and preferred embodiments cited with regard to the method also apply to the device.

[0014] The process is used to produce a strand product, specifically a cable or hose, which has a casing that is extruded with a predetermined wall thickness using an extrusion unit. In a conveying or extrusion direction downstream of the extrusion unit, a portion of the still formable material is then accumulated using a forming unit during a forming process, so that a molded part is formed integrally on the casing. The forming unit is moved according to a predetermined work cycle, which comprises the following steps: The forming unit is first accelerated from an initial position in the conveying direction and synchronized to a line speed at which the casing is extruded. The forming unit typically has a speed of zero at the initial position. The forming unit is then advanced towards the strand product.This generally means that the forming unit is advanced in such a way that it engages the still-formable material of the shell, thus achieving the desired accumulation of material and, in particular, the formation of the formed part. During the forming process, the forming unit is therefore in the advanced state. After the forming process, the forming unit is retracted from the extruded material, so that the forming unit is no longer in engagement with the shell. Finally, the forming unit is decelerated and moved from an end position back toward the starting position, counter to the conveying direction.

[0015] The process cycle or work cycle is therefore characterized by a sequence of positive and negative accelerations of the mold unit to periodically move it back and forth between the starting position and the end position. In a velocity-time diagram, the sum of all areas above and below a zero velocity line, each of which indicates a measure of the distance traveled, would be zero.

[0016] The molding unit is expediently moved linearly along a linear guide between the starting position and the end position. Overall, it has been shown that such a design, with the molding unit moved along a linear travel path in and against the conveyor device to form a periodically recurring working section, is particularly easy to implement in terms of process technology in order to be able to achieve the desired high process speeds and, in particular, to be able to design a sufficiently robust device that can withstand the high counterpressures during the molding process. The design of the linear guide in particular allows the forces to be reliably absorbed. In addition to the pressures during the molding process, this also applies in particular to the dynamic loads due to the high process speeds and the high accelerations required for the molding unit.

[0017] The work cycle is designed for the forming unit to move at a forming speed different from the line speed during the forming process. This speed can be either higher or lower than the line speed, thus establishing a relative speed between the forming unit and the strand material, which creates the desired accumulation within the forming unit.

[0018] The line speed is preferably in the range between 0.1 m / s or 0.5 m / s to 4 m / s and in particular around 2 m / s.

[0019] In a preferred embodiment, starting from the starting position, the forming unit is first accelerated to the line speed, so that the relative speed is initially zero. The forming unit is then advanced in the direction of the extruded material, which ensures that it is inserted in a direction particularly perpendicular to the conveying direction and, in particular, allows defined surfaces to be formed for the formed part. After the forming unit has been advanced, i.e. after it has been at least partially inserted into the shell material, the forming unit is accelerated and brought up to the forming speed. In this case, acceleration is generally understood to mean either positive acceleration or negative acceleration (braking). The transition to the forming speed preferably takes place at maximum acceleration.

[0020] The forming speed differs from the line speed, with the difference being in the range of 0.01 m / s to 0.3 m / s, and in particular 0.05 m / s to 0.2 m / s. The difference is preferably about 5 to 20%, and in particular about 10%, of the line speed.

[0021] According to a first embodiment, the forming speed is constant during the forming process. In an alternative configuration, the forming speed varies during the forming process. For example, a continuous increase or decrease in the forming speed is provided. Specifically, it is also provided that the forming speed is changed such that it is higher than the line speed in a first section and lower in a second section. This therefore enables accumulation in or against the conveying direction. In general, different profiles and shapes of the molded parts to be formed can be achieved by adjusting the forming speed, particularly in combination with the geometry of the forming unit.

[0022] After the forming process, the forming unit is returned to the extruded material. This process is also referred to below as demolding. For this demolding process, it is expedient that the forming unit is first brought from the forming speed to a demolding speed. In general, this means that the forming unit is moved at least a short distance away from the molded part in or against the conveying direction before demolding takes place. Expediently, the demolding speed is again the line speed, so that the relative speed between the forming unit and the extruded material is once again zero. With this variant, for example, an exact 90° demolding is possible. In principle, however, other demolding speeds can also be provided, so that, for example, special demolding contours can also be formed.

[0023] According to a first preferred embodiment, the starting and / or end positions are identical across multiple working cycles, and preferably across all working cycles. In particular, both the starting and end positions are identical. This means that in each working cycle, the molding unit moves from the identical starting position to the identical end position and back again. This is especially the case when forming periodically repeating identical molded parts.

[0024] In an alternative embodiment, the starting and / or end position varies between two consecutive work cycles, or intermediate positions are approached during a work cycle. In an alternative embodiment, several working and / or end positions or intermediate positions are therefore formed. In this case, expediently only a limited number of different working and / or end positions are provided, for example a maximum of three different working positions and / or three different end positions. Different working and / or end positions are provided in particular when different molded parts are provided, which differ, for example, in terms of their size or shape. Alternatively, different starting and end positions are also provided when there are different distances between two consecutive molded parts.

[0025] In general, the method described here is used to produce periodically recurring structures. An overall working cycle is provided, which can preferably be divided into several working cycles. Several overall working cycles follow one another, and during each overall working cycle, an identical sequence of preferably several molded parts takes place, which can also be differently designed.

[0026] For example, a complete cycle involves manufacturing a defined cable section, and the entire cable harness is separated after each such cable section and, if necessary, pre-assembled with connectors, etc. Such a cable section later forms a defined length for a cable set.

[0027] The distance between a respective starting position and the end position defines a total travel path (in one direction) for the forming unit. This distance preferably lies only in a range of 0.5 m to 5 m, and in particular in a range of 1 m to 2 m.

[0028] In principle, in addition to the linear movement in or against the conveying direction, an additional feed movement toward or away from the extruded material is required. This feed movement preferably occurs exactly perpendicular to the conveying direction. For this feed movement, an additional feed drive is designed in addition to the (linear) drive for the linear movement in / against the conveying direction. The overall movement of the forming unit therefore occurs through the superposition of two movements, in particular linear movements: on the one hand, in / against the conveying direction and, on the other hand, in or against the feed direction perpendicular to the conveying direction.

[0029] Embodiments of the invention are explained in more detail below with reference to the figures, some of which are simplified representations: Fig. 1 a strand material which is passed through an extrusion unit and a device for forming shaped parts, Fig. 2 an enlarged detail in the area of the device with a forming unit, Fig. 3 an exemplary side view of a cable with formed shaped parts, Fig. 4A a speed-time diagram (vt diagram) for a working cycle of the forming unit, Fig. 4B for Fig. 4A associated speed-distance diagram (vs-diagram), Fig. 5 a simplified speed-time diagram with a third axis for the feed movement with feed speed, Fig. 6A to 6D various speed-time diagrams to illustrate different work cycles, Fig. 7 an exemplary representation of a device with the linearly movable forming unit.

[0030] In the figures, parts with the same function are shown with the same reference symbols.

[0031] Basic steps of the process for producing a strand 2 by accumulating material are first described using the Fig. 1 explained. This shows a longitudinal section of the extruded material 2 extending in a longitudinal direction L, which comprises an inner core 4 and a sheath 6 applied thereto. The extruded material 2 is designed here as a cable, with a core which is correspondingly a cable core and has, for example, one or more conductors, wires, lines and / or partial cables. Alternatively, the extruded material 2 is a hose and the core 4 is then correspondingly a hose core. In the exemplary embodiment shown here, the sheath 6 is in particular an outer sheath of the extruded material 2. The extruded material 2 can be designed as a semi-finished product and can be further processed. To apply the sheath 6, the core 4 is first fed in a conveying direction F to an extrusion unit 8. By means of this, a predetermined material, usually a plastic, is extruded onto the core 4 as a sheath 6.

[0032] In the conveying direction F, a device 10 for shaping shaped parts 12 is arranged downstream of the extrusion unit 8. The extrusion unit 8 and the device 10 are part of a production line through which the extruded material is fed at a line speed. The line speed, in particular the extrusion speed, and a distance d between the shaping unit 10 and the extrusion unit 8 are selected such that the material of the shell 6 is still shapeable when it reaches the device 10. By means of this device 10, at least a portion of the material of the shell 6 is accumulated and used to form the shaped part 12. The shaped part 12 is formed directly from the material of the shell 6 of the extruded material 2. Therefore, material of the shell is essentially scraped off the initially finished shell 6 and accumulated to shape the shaped part.

[0033] In Fig. 1 , a molded part 12 is shown as an example, designed as a cylindrical thickening of the shell 6. This is also formed only on a specific molded part section d1 of the extruded material 2, to which extruded material sections d2 with a substantially uniform wall thickness W of the shell 6 are connected. In the exemplary embodiment shown here, a plurality of molded parts 12 are also formed at periodically recurring length positions, so that between two molded parts 12 following one another in the longitudinal direction L, a extruded material section Ad with a specific length extends, in particular unaffected by the molding unit 10. To form the molded parts, the device 10 comprises a molding unit 14, as shown by way of example in Fig. 2 is shown in more detail.

[0034] The molding unit 14 is in particular designed in several parts and in particular comprises two mold halves, which are referred to as mold cavities 16. The two mold cavities 16 are preferably moved synchronously with one another. Overall, the molding unit 14 is moved linearly in the conveying direction F and perpendicular thereto in a feed direction Z, in particular perpendicular to the conveying direction F, and is thereby fed towards the shell 6. In this case, the respective mold cavity 16 preferably only partially moves into the shell 6 and the molding unit 10 is virtually closed. Due to a difference in speed between the molding unit 14 and the extruded material 2, shell material is scraped off and accumulated, which is collected in a molding chamber 18 of the molding unit 14 so that the latter is preferably completely filled with the material.The mold unit is then opened again by resetting the mold cavities 16, so that a molded part 12 with a defined contour is formed according to the specifications of the mold chamber 18.

[0035] The Fig. 2 The forming unit 12 shown is used in variants in which the speed of the strand material 2 in the conveying direction F is faster than the speed of the forming unit 14, so that a rearward accumulation occurs. In principle, however, it is also possible to move the forming unit 14 at a higher speed than the strand material 2 in the conveying direction F, so that a front-side accumulation, also referred to as pushing up, occurs. In principle, the Fig. 2 shown mold unit can also produce a pushed-on molded part 12 in the case of a mirror-image design or rotation.

[0036] Based on the Fig. 3 a variant of a cable 20 is shown as strand material 2, in which two shaped parts 12 are designed in the manner of grommets, which have, for example, a trapezoidal cross-section. In this embodiment, individual wires 22 of the cable 20 are exposed between the two shaped parts 12. In this variant, therefore, not only a part of the sheath 6 is scraped off, but rather the entire sheath material is accumulated. As can be seen, the shaped parts are manufactured in mirror image with respect to a plane that is perpendicular to the conveying direction F. The shaped part 12 shown on the right-hand side is manufactured by pushing on and the shaped part 12 shown on the left-hand half of the image is manufactured by rearward accumulation.

[0037] To produce the molded parts 12, the mold unit 14 or several mold units 14 are moved according to a predetermined work cycle. In particular, two linear travel paths are superimposed. Firstly, the mold unit 14 is moved linearly in and against the conveying direction F. In addition, the mold unit 14, in particular the mold cavities 16, are moved perpendicularly thereto in or against the feed direction Z. The respective work cycle is described below, firstly based on the Fig. 4A , 4B explained in more detail.

[0038] At the beginning of the working cycle at a starting position A, the forming unit 14 initially has a speed of zero. From this, it is accelerated in a first step, preferably with the maximum possible acceleration, to a speed v1, which is in particular the line speed at which the extruded material 2 is conveyed in the conveying direction F. In the exemplary embodiment, this is 2 m / s. In a second step, the speed v1 is maintained. During this time, an infeed movement takes place in the direction of the extruded material 12, so that the mold cavities 16 at least partially engage the shell material. The forming unit 14 is then accelerated further, in the exemplary embodiment a deceleration, likewise preferably with the maximum negative acceleration, so that a forming speed v2 is obtained which is different from the line speed v1. The difference is, for example, 0.05 m / s to 0.2 m / s.Due to this difference, the mold chambers 18 are filled with shell material. In the design variant of the . Fig. 4A , 4B Therefore, the molding speed v2 is maintained for a certain period of time until the molding chamber 18 is preferably completely filled. This step is also referred to as the molding process.

[0039] After completion of the forming process, a further acceleration takes place, in this case a positive acceleration, again preferably with maximum positive acceleration to a demolding speed, preferably again to the line speed v1, which is then maintained for the demolding process. During the demolding process, the mold cavities 16 open against the feed direction Z. As soon as the mold unit 14 is fully opened, a further acceleration takes place, namely a braking of the mold unit 14 to zero and acceleration to a negative, in particular maximum, return speed v3. This is preferably greater than the line speed, in particular by a factor of 1.5 to 2. Different acceleration values can be adopted during the braking process. Braking to zero again preferably takes place with the maximum possible negative acceleration.The subsequent acceleration to the return speed, for example, occurs with a somewhat lower negative acceleration. The return speed v3 is negative compared to the line speed v1, i.e. the forming unit 14 is moved back towards the starting position A. When the speed is reached at zero, the forming unit 14 reaches an end position E of the working cycle as the maximum position in the conveying direction F. From the return speed v3, the forming unit 10 is decelerated again to the speed zero. At this point, the starting position A is reached again. The starting position A and the end position E are spaced apart by a distance a of, for example, 1-3 m.

[0040] The maximum positive and negative acceleration are preferably equal. The maximum acceleration values are preferably in the range of 20 to 50 m / s 2< or even up to 100 m / s 2<, and especially 40 m / s 2<.

[0041] The work cycle then begins again.

[0042] In Fig. 5 Using a simplified speed-time diagram, the feed speed vz of the second linear movement in the feed direction Z or against the feed direction Z when retracting the mold cavities 16 or when opening the mold cavities 16 is additionally shown on a further axis. In both cases, the respective mold cavity 16 is moved perpendicular to the conveying direction F with the maximum possible acceleration and is decelerated to reach the retracted position and remains in this position. Conversely, i.e. when retracting, the mold cavity remains in the retracted position.

[0043] In connection with the Fig. 6A bis 6D different speed-time diagrams are shown. Fig. 6A shows a travel cycle at least until the formation of the molded part 12 similar to that in the Fig. 4A The braking takes place to the return speed v3, which is then maintained for a certain period of time. Fig. 6A bis 6C Some accelerations are shown as vertical lines. This is an idealized representation and is intended only to indicate a maximum acceleration.

[0044] In the version of the Fig. 6B A situation is shown in which, for example, the acceleration in the first step to the line speed v1 runs along a given curve. The accelerations to reach the form speed v2 can also vary.

[0045] It should be emphasized that Fig. 6 shows a variant of an overall cycle, which consists of two superimposed subcycles. After the first formed part 12 has been formed, the forming unit 14 is decelerated to a negative speed v4 and moved back a short distance relative to the strand material 2, but not to the original starting position, but rather to a second starting position for the forming unit 10. From this position, a positive acceleration then occurs again to a positive speed v5, which is lower than the forming speed v2.

[0046] This additional step can be superimposed by a further feed movement, so that, for example, an additional molded part 12 is formed, for example a molded part 12 that is smaller than the first molded part 12. Only then does a return to the original starting position A take place by further braking. Overall, the sum of the areas above zero speed and below zero speed is identical.

[0047] In the design variants of the Fig. 6C, 6D Two situations are shown in which a variable forming speed v2 or different, but constant forming speeds v2 are adopted during the forming process. In the variant of the Fig. 6C For example, after deceleration to a minimum forming speed v2, a continuous, particularly linear, increase of this forming speed v2 is provided. Specifically, an increase occurs up to a speed greater than the line speed v1. With this measure, both rearward accumulation and frontal pushing-up can be achieved with the delivered forming unit 12.

[0048] It is advisable to first push the load forward and then back up the load. Unlike in the Fig. 6C As shown, a form speed v2 is initially set above the line speed v1, which is then reduced.

[0049] In Fig. 6D A similar situation is shown, but here the form speed v2 is not continuously varied. Rather, a first section 34 with a form speed v2 below and a second section 36 with a form speed v2 above the line speed v1 are provided.

[0050] This also allows accumulation and pushing up to form two molded parts 12 separated from each other in the conveying direction F, for example the one shown in Fig. 2 Cable 20 shown. Contrary to the illustration of the Fig. 6D - initially due to the high forming speed v2 a frontal pushing up and subsequently due to the lower forming speed v2 a rearward damming up of the two in Fig. 2 recognizable molded parts 12 are produced.

[0051] Overall, such a travel concept enables a wide variety of speed and thus travel profiles within a work cycle with two superimposed linear movements, so that different molded parts 12 can also be formed.

[0052] In Fig. 7 A variant of the device 10 is shown as an example. The entire device 10 has a length L which is only slightly greater than the distance a between the starting position A and the end position E. For example, the length L is only 10% to 30% greater than the distance a. In the exemplary embodiment, the device 10 has a support frame 24 which is preferably fixedly connected to a floor. A linear guide 26 is arranged on this support frame 24. A carriage 28 is arranged on this linear guide 26 so as to be displaceable in the conveying direction F. The carriage 28 can be moved between the starting position A and the end position E. The forming unit 14 is arranged on the carriage 28 and is therefore moved with the carriage 28.

[0053] In a manner not shown in detail, a drive, in particular a linear drive, specifically an electric motor-driven linear drive, is provided for moving the carriage 28 along the linear guide 26. In addition, a feed drive (not shown in detail here) is provided, which ensures the feed movement of the two mold cavities 16 in the feed direction Z.

[0054] The entire device 10 further comprises an inlet opening 30 and an outlet opening 32 through which the strand material 2 is introduced into the device 10 and is led out of it again.

[0055] The device 10 is - as in Fig. 1 indicated - integrated within a production line for the production of the extruded material 2. The shaped parts 12 are therefore formed continuously at periodically recurring intervals on a quasi-endless extruded material 12 as part of an inline process.

Claims

1. Method for producing an extrudate with a sheath, in which method, by means of an extruder unit, the sheath is extruded with a predefined wall thickness, wherein, downstream of the extruder unit in a conveying direction, part of the still malleable material is accumulated with the aid of a mould unit during a shaping process in such a way that an integral moulding is formed on the sheath, wherein the mould unit is moved according to the following operating cycle, - the mould unit is accelerated from an initial position in the conveying direction, - the mould unit is actuated in the direction towards the extrudate, and the moulding is formed, - the mould unit is retracted from the extrudate, - the mould unit is decelerated and displaced from a terminal position, counter to the conveying direction, back in the direction towards the initial position, wherein the extrudate is conveyed in the conveying direction at a predefined linear speed, and the mould unit during the shaping process is displaced at a mould speed different from the linear speed, characterized in that the moulding is moulded directly from the material of the sheath in that the material of the sheath is scraped from the initially completed sheath and is accumulated for shaping the moulding, wherein the mould unit is displaced linearly along a linear guide between an initial position and a terminal position.

2. Method according to Claim 1, in which the mould unit is displaced between the initial position and the terminal position with the aid of a linear drive.

3. Method according to Claim 1 or 2, in which the linear speed is in the range from 0.1 m / s to 4 m / s, and is in particular 2 m / s.

4. Method according to one of the preceding claims, in which the mould unit is initially accelerated to the linear speed, then actuated in the direction towards the extrudate, and thereafter brought to the mould speed.

5. Method according to one of the preceding claims, in which the mould speed differs from the linear speed in the range from 0.01 m / s to 0.3 m / s.

6. Method according to one of the preceding claims, in which the mould speed is constant during the shaping process.

7. Method according to one of Claims 1 to 5, in which the mould speed varies during the shaping process.

8. Method according to one of the preceding claims, in which during the shaping process the mould speed in a first sub-portion is higher, and in a second sub-portion is lower, than the linear speed.

9. Method according to one of the preceding claims, in which the mould unit upon forming the moulding is brought from the mould speed to a demoulding speed, the latter being in particular the linear speed, before the mould unit is retracted from the extrudate.

10. Method according to one of the preceding claims, in which the initial position and the terminal position are identical over a plurality of operating cycles.

11. Method according to one of Claims 1 to 9, in which a plurality of operating and / or terminal positions are provided, in particular so as to form different mouldings.

12. Method according to one of the preceding claims, in which a spacing between the initial position and the terminal position is in the range from 0.5 to 5 m, and in particular in the range from 1 m to 2 m.

13. Method according to one of the preceding claims, in which the actuation in the direction towards the extrudate and back from the latter is performed perpendicularly to the conveying direction.

14. Device configured for producing a moulding on an extrudate by means of a method according to one of the preceding claims, having - a linear guide for a mould unit so as to displace the latter between the initial position and the terminal position, - a drive, in particular a linear drive, for accelerating the mould unit, characterized in that the device is configured to move the mould unit linearly along a linear guide between an initial position and a terminal position according to the following operating cycle, - the mould unit is accelerated from the initial position in the conveying direction, - the mould unit is actuated in the direction towards the extrudate, and the moulding is formed, - the mould unit is retracted from the extrudate, - the mould unit is decelerated and displaced from a terminal position, counter to the conveying direction, back in the direction towards the initial position, wherein the extrudate is conveyed in the conveying direction at a predefined linear speed, and the mould unit during the shaping process is displaced at a mould speed different from the linear speed, wherein the moulding is moulded directly from the material of the sheath in that the material of the sheath is scraped from the initially completed sheath and is accumulated for shaping the moulding.

15. Device according to Claim 14, additionally having an actuating drive for actuating the mould unit in a direction perpendicular to the conveying direction.