Method for producing a high pressure hydraulic line

Abstract

In the process for manufacturing a high-pressure hydraulic line, a connecting fitting is attached to the end of a high-pressure hose, wherein a section of a high-pressure hose (3) and a connecting fitting comprising a nipple (4) and a crimp sleeve (5) to be joined to it are provided, the connecting fitting is placed on an end section of the high-pressure hose (3), the line blank (2) thus produced is inserted into a program-controlled radial press (1) and a joining operation is carried out in the radial press (1) by plastic deformation of the crimp sleeve (5) when the crimping tool (6) is forced closed according to a crimping program (P), forming a tight connection between the high-pressure hose (3) and the connecting fitting.In this process, when the press tool (6) is closed, the geometric configuration of the press tool (6) is detected when the press jaws (7) are placed on the press sleeve (5); and the press program (P) traversed by the radial press (1) is formed by specific adaptation of a basic program (B) stored in the radial press (1) taking into account the configuration of the press tool (6) detected when the press jaws (7) are placed on the press sleeve (5).

Description

[0001] The present invention lies in the technical field of manufacturing high-pressure hydraulic lines. In particular, as specified in detail in the preamble of claim 1, the invention lies in the field of methods in which a high-pressure hose and a connecting fitting comprising a nipple and a crimp sleeve are permanently joined together by means of plastic radial deformation of the sleeve, wherein the plastic radial deformation is carried out by means of a program-controlled radial press with a pressing tool comprising a plurality of pressing jaws arranged around a pressing axis, namely by providing a section of the high-pressure hose and the connecting fitting to be joined thereto, placing the connecting fitting onto an end section of the high-pressure hose, and inserting the line blank thus produced into the program-controlled radial press.The crimp sleeve is placed in the open crimping tool of the radial press, and a joining operation is carried out in the radial press, creating a tight connection between the high-pressure hose and the fitting, through plastic deformation of the crimp sleeve when the crimping tool is forced closed according to a crimping program. The sealing surface is generally the inner surface of the high-pressure hydraulic hose, which is pressed more or less tightly against the nipple by means of the crimp sleeve.

[0002] With regard to such processes, and especially the radial presses used in these processes, there is a diverse range of prior art. For aspects of process control, reference should be made, for example, to US 5,651,282 A, WO 2010 / 120373 A2, WO 2016 / 162890 A1, DE 10 2018 115 750 B3 and US 6,237,204 B1.For example, aspects of the radial presses used are addressed in DE 10 2014 012 485 B3, DE 10 2009 057 726 A1, DE 10 2011 015 770 A1, DE 199 12 976 A1, DE 20 2016 100 660 U1, DE 41 35 465 A1 and WO 2001 / 033675 A1 (concerning radial presses in yoke press design), DE 10 2017 119 403 A1, DE 10 2016 106 650 A1 and EP 1 302 255 A1 (concerning radial presses in hollow piston press design), EP 239 875 A2, DE 10 2011 015 654 A1 and WO 1981 / 003456 A1 (concerning radial presses in a pressure platen press design) and DE 199 40 744 A1, WO 2002 / 024374 A1, DE 10 2012 025 134 A1, DE 298 24 688 U1, EP 17 660 A1 and EP 2 786 817 B1 (concerning radial presses in other designs). US 2013 / 160284 A1, which forms the basis for the preamble of claim 1, discloses a radial press for crimping a first component onto a second component.

[0003] The quality of the connection between the fitting and the high-pressure hose is extremely important from the perspective of occupational and operational safety. A failure of the connection (so-called "hose rupture") poses a very significant risk to the health and physical integrity of people in the vicinity, not to mention property damage (for example, environmental damage caused by released hydraulic fluid). The fact that ensuring safety against hose rupture presents a particular challenge for high-pressure hydraulic lines manufactured according to the generic manufacturing process is related to several technical characteristics of the components and joining techniques used. For one thing, the high-pressure hose is flexible, meaning...The wall of the hose – which is clamped between the nipple and the crimp sleeve – is elastically compressible in the radial direction. However, excessive compression leads to damage to the hose, which in turn can result in premature failure of the pressurized high-pressure hydraulic line. Furthermore, unlike rigid pipes, which are connected using a fitting pressed onto the outside and sealed against the pipe's outer surface, the high-pressure hydraulic hose can deflect laterally, increasing the risk of hose tearing.

[0004] In light of the problems outlined above, there is a constant need for measures suitable for further improving the generic processes for the manufacture of high-pressure hydraulic lines under discussion, particularly with regard to the reliability of the manufactured hydraulic lines.

[0005] The present invention aims to make a contribution in the aforementioned respect.

[0006] This problem is solved according to the invention by capturing the geometric configuration of the pressing tool when the pressing jaws are placed on the pressing sleeve during the closing of the pressing tool in generic methods for manufacturing a high-pressure hydraulic line, and by forming the pressing program traversed by the radial press through specific adaptation of a basic program stored in the radial press, taking into account the configuration of the pressing tool captured when the pressing jaws are placed on the pressing sleeve.According to the present invention, the pressing program that the radial press executes for the plastic deformation of the press sleeve to create a tight seal between the fitting and the high-pressure hose is individually determined during the manufacturing process for the high-pressure hydraulic line being produced. This is achieved by individually and specifically adapting a basic program stored in the radial press, taking into account the configuration of the pressing tool when the jaws are placed on the press sleeve. The relevant geometric configuration of the pressing tool, used for the individual adaptation of the basic program applicable to the respective components (high-pressure hydraulic hose and fitting) of the high-pressure hydraulic line, is detected when the pressing tool closes, at the moment the jaws are placed on the press sleeve.This allows even relatively small deviations in the dimensions of the crimp sleeve from the nominal dimension, which are still within the permissible tolerance, to be detected and taken into account when creating / calculating the crimping program to be applied to the individual crimping process. The corresponding consideration of the exact initial dimensions of the sleeve of the connection fitting, i.e., a specific individually determined oversize or undersize compared to the nominal dimension, can result in a corresponding shift in the final dimension determined by the individual crimping program for the respective crimping process.

[0007] Thus, by individually adapting the press program to the respective individual workpiece or an individual group of workpieces (su), it is surprisingly easy to produce high-pressure hydraulic lines with very good reproducibility and consequently of very good quality with comparatively little effort.

[0008] From the following explanations, particularly those of the embodiment illustrated in the drawing, it is evident that the conductor blank can be in contact with a press jaw, specifically resting on it, from the very beginning of the radial press's closing action. It should be emphasized that, within the scope of the invention, the specific adaptation of the basic program focuses on the contact of the press jaws (plural!) with the press sleeve. In other words, the crucial factor is the geometric configuration of the pressing tool at the moment when at least two (preferably opposing) press jaws make contact with the press sleeve.

[0009] In a particularly preferred embodiment of the invention, the specific adaptation of the basic program stored in the radial press consists of determining the specific final dimension for the force-closing action of the press tool while simultaneously influencing the force-displacement characteristic curve traversed up to that point. In this sense, starting from the basic program stored in the machine control, both the final dimension for the force-closing action of the press tool and the shape (e.g., the local gradient) of the force-displacement characteristic curve can be specifically and individually modified as a function of the initial dimension of the sleeve of the connecting fitting. This takes into account the understanding that a dimensional deviation can often be accompanied by a deviation in material properties, which can be addressed by a suitable modification of the pressing characteristic curve.However, under typical practical conditions, the advantages achievable through the invention can generally be realized to a significant degree even if the specific adaptation of the basic program stored in the radial press "only" consists of determining the specific final dimension for the force closing of the press tool, while no additional influence is exerted on the force-displacement characteristic curve traversed up to that point.

[0010] According to another preferred embodiment of the invention, the configuration of the pressing tool is detected directly at the pressing tool when the pressing jaws are placed on the pressing sleeve. In this sense, for example, the distance between two diametrically opposed pressing jaws can be monitored when the pressing tool closes using suitable sensors known as such, and the pressing jaw distance existing at the moment the pressing jaws are placed on the pressing sleeve can be used for the specific adaptation of the pressing program to be executed.

[0011] Alternatively, depending on the specific type of radial press, it can also be advantageous to indirectly capture the configuration of the press tool when the press jaws are placed on the press sleeve by capturing the configuration of a drive unit acting on the press tool. In this sense, for example, the precise geometric configuration of an actuator belonging to the drive unit (e.g., the position of the piston of a hydraulic cylinder) or a transmission element can be monitored when the press tool closes, and the configuration of the actuator or transmission element existing at the moment the press jaws are placed on the press sleeve can be used for the specific adaptation of the press program to be executed.

[0012] A particularly preferred embodiment of the inventive method is characterized by the fact that, for a production batch comprising several identical high-pressure hydraulic lines, the specific adaptation of the basic program stored in the radial press is carried out individually for each individual pressing operation, taking into account the configuration of the pressing tool as determined when the pressing jaws are placed on the pressing sleeve. A characteristic feature of this embodiment is that, for all "identical" high-pressure hydraulic lines to be produced within a production batch, a uniform crimping final dimension (e.g., determined individually during the first crimping operation from the production batch) does not apply, but rather this dimension is determined individually for each individual crimping operation. In this way, the potential inherent in the present invention can be optimally utilized.

[0013] In particular, if the initial dimensions of the press sleeves of the connecting fittings differ to a relevant extent from production batch to production batch, but there is a maximum degree of uniformity of the press sleeves with regard to their actual dimensions within a production batch, the quality advantages of the manufactured high-pressure hydraulic lines achievable by the present invention also result if, according to an alternative preferred embodiment of the invention, the specific adaptation of the basic program stored in the radial press is carried out for a production batch comprising several identical high-pressure hydraulic lines, taking into account the configuration of the pressing tool detected when the pressing jaws are placed on the press sleeve, during the first pressing operation of the production batch and is maintained for subsequent pressing operations.

[0014] It should be noted that for the present invention and its associated advantages, it is clearly irrelevant whether the high-pressure hose is more or less flexible. In this respect, even pipes suitable for the manufacture of high-pressure hydraulic lines, which are not flexible in their intended use or do not need to be flexible, but are rather commonly referred to as "rigid," constitute "high-pressure hoses" within the meaning of the present invention. Moreover, the process and structural features that characterize these hoses can be used in various other, similarly structured joining applications, which are also characterized by the radial deformation of at least one component of a component pair prepared as a blank, such as shaft connections, insulator connections, anchor connections, and the like.

[0015] The present invention will now be explained in more detail with reference to a preferred embodiment illustrated in the drawing. Fig. 1 shows a radial press suitable and prepared for carrying out the method according to the invention; and Fig. 2 illustrates the process using the radial press according to Fig. 1 achievable procedural conduct.

[0016] The in Fig. 1 The radial press 1 shown as an example corresponds in its construction and function to that of DE 41 35 465 A1. Unless otherwise explained below, it is therefore identical to the well-known and established prior art. To avoid unnecessary elaboration, reference is made to the content of DE 41 35 465 A1. The process state immediately before the start of the pressing process is illustrated. A pipe blank 2, which – in the usual manner – comprises a section of a high-pressure hose 3 and a connecting fitting mounted on one end section thereof, having a nipple 4 (inserted inside the high-pressure hose 3) and a crimp sleeve 5 (mounted on the outside of the high-pressure hose 3), is inserted into the open pressing tool 6 such that the crimp sleeve 5 rests on the lower pressing jaw 7u.Also shown is an operating, control and monitoring unit 8 belonging to the radial press 1, which controls both the electric motor 10 driving the hydraulic pump 9 and the valve unit 11. In this respect as well, the radial press 1 shown is still within the realm of generally known prior art, even if this is not explicitly stated in DE 41 35 465 A1.

[0017] The radial press 1 is modified according to Fig. 1 Compared to the one according to DE 41 35 465 A1, this device differs in that it has a sensor (distance sensor) 14 that detects the distance between the upper yoke 12 and the lower yoke 13 relative to each other, instead of a combination of adjusting spindle and microswitch for limit switch operation. The distance signal generated by this sensor 14 is transmitted to the operating, control, and monitoring unit 8 via a signal line 15. Furthermore, the base jaw 16 of the upper press jaw 70 is equipped with a deformation sensor 17 (e.g., in the form of a strain gauge 18 attached to the face of the base jaw 16). The signal generated by the deformation sensor 17 is also transmitted to the operating, control, and monitoring unit 8 via a signal line 19.

[0018] When the operator of the radial press 1 triggers the pressing process, the pressing tool 6 closes around the workpiece, i.e., the pipe blank 2, in the usual manner – in implementation of a pressing program generated by the operating, control and monitoring unit 8. At the beginning of the pressing process, the pressing program corresponds to a basic program stored in the operating, control and monitoring unit 8, which applies to the parts to be joined.

[0019] The press sleeve 5, resting on the lower press jaw 7u, gradually approaches the upper press jaw 7o. The moment the latter contacts the press sleeve 5, the load and stress situation in the upper press jaw 7o changes, i.e., particularly (also) in its base jaw 16. This is detected by the deformation sensor 17 via a corresponding induced deformation of the base jaw 16. The distance value between the upper yoke 12 and the lower yoke 13, provided by the sensor 14 at this moment, is used as a reference value for the subsequent force pressing.In this process, a pressing program is executed, which is based on the basic program stored in the operating, control, and monitoring unit 8 and applies to the pressing of the selected combination of high-pressure hose and connection fitting. However, this program is specifically adapted for the individual workpiece, taking into account the precise configuration of the pressing tool 6, which it assumes when the upper pressing jaw 70 is placed on the pressing sleeve 5 and which is detected by the sensor 14. In particular, any deviation of the actual dimension of the pressing sleeve 5 from the nominal dimension, in the sense of a shift in the final dimension of the press fit, is taken into account.

[0020] This is illustrated in Fig. 2 Based on a (schematic, highly exaggerated) diagram showing the distance D between the two yokes 12, 13, which is crucial for the geometric configuration of the press tool 6, over time t, specifically for the three phases closing (I), holding (II), and opening (III). This is based on the operation of the radial press 1 with a hydraulic pump 9 designed as a constant-flow pump, so that the closing of the press tool by pressurizing the two press cylinders 20, as well as the opening of the press tool by pressurizing the return stroke cylinder 21, each occurs at a constant speed. Due to the significantly smaller cross-section of the return stroke cylinder 21 compared to the combined area of ​​the two press cylinders 20, the opening of the press tool 6 of the radial press 1 – at the same delivery rate of the hydraulic pump 9 – occurs at a significantly higher speed than the closing.

[0021] According to the basic program B stored in the operating, control and monitoring unit 8, which is designed for a nominal diameter DN of the press sleeve 5, the radial press 1 closes from an initial dimension D 0 to a nominal press final dimension D NE. Here, it switches to "hold" mode for the holding time t HN. After the holding time has elapsed, the radial press 1 fully opens back to the initial dimension D 0.

[0022] If the press sleeve 5 to be pressed in the individual pressing process has an actual diameter DI that deviates from the nominal diameter DN, the pressing program is modified. For example, if, as described above, the actual diameter DI of the press sleeve 5 is larger than the nominal diameter DN, the pressing dimension for the actual pressing program P is shifted from the nominal pressing dimension D NE to the (correspondingly larger) actual pressing dimension D IE. The extent of this adaptation of the basic program B corresponds to the difference between the actual diameter DI and the nominal diameter DN of the press sleeve 5, so that for the actually pressed press sleeve 5, the deformation dimension ΔD I corresponds to that for which the basic program B – which is based on press sleeves that comply with the nominal diameter DN – is designed (ΔD N ).

[0023] For undersized press sleeves 5, the above applies accordingly, with the result that the actual press dimension D IE is smaller than the nominal press dimension D NE .

[0024] In the Fig. 2 In the illustrated case, the holding time is not changed by adapting the basic program B; the actual holding time t HI observed during pressing therefore corresponds to the holding time t HN specified in the basic program B. However, it is evident that an adaptation can also be made with regard to the holding time, for example, by always maintaining a longer holding time t HI as a precaution when pressing workpieces that deviate from the design case underlying the basic program B.

[0025] Based on the foregoing explanation, the corresponding implementations of the present invention in differently designed radial presses, in particular in hollow piston presses and pressure plate presses (so), in radial presses with drives other than hydraulic drives, in radial presses with variable closing speed (for example, by using a servo pump or proportional valves), in radial presses with a separate closing rapid drive, etc., are readily apparent to a person skilled in the art. Similarly, the implementation of the invention is readily apparent to a person skilled in the art in such a way that the configuration of the press tool is not directly detected at the press tool itself when the press jaws are placed on the press sleeve, but rather indirectly detected by directly detecting the configuration of a drive unit acting on the press tool.

Claims

1. Method for manufacturing a high-pressure hydraulic line by attaching a connecting fitting to the end of a high-pressure hose, comprising - providing a portion of a high-pressure hose (3) and a connecting fitting to be joined to it, comprising a nipple (4) and a press sleeve (5), - placing the connection fitting on an end section of the high-pressure hose (3), - inserting the line blank (2) thus produced into a program-controlled radial press (1), whereby the press sleeve (5) comes to rest in the open press tool (6) of the radial press (1), which comprises a plurality of press jaws (7) arranged around a press axis, - Performing a joining operation to form a tight connection between the high-pressure hose (3) and the connecting fitting in the radial press (1) by plastically deforming the press sleeve (5) when the press tool (6) is closed by force in accordance with a press program (P), characterized in that - when the pressing tool (6) is closed, the geometric configuration of the pressing tool (6) is detected when the pressing jaws (7) are placed on the press sleeve (5), and - the pressing program (P) executed by the radial press (1) is formed by specific adaptation of a basic program (B) stored in the radial press (1), taking into account the configuration of the pressing tool (6) detected when the pressing jaws (7) are placed on the press sleeve (5).

2. Method according to claim 1, characterized in that the configuration of the pressing tool (6) when the pressing jaws (7) are placed on the press sleeve (5) is detected directly at the pressing tool (6).

3. Method according to claim 1, characterized in that the configuration of the pressing tool (6) when the pressing jaws (7) are placed on the press sleeve (5) is indirectly detected by directly detecting the configuration of a drive unit acting on the pressing tool (6).

4. Method according to one of claims 1 to 3, characterized in that, for a production batch comprising several identical high-pressure hydraulic lines, there is carried out individually for the respective pressing process the specific adaptation of the basic program (B) stored in the radial press (1), taking into account the configuration of the pressing tool (6) captured when the pressing jaws (7) are placed on the press sleeve (5).

5. Method according to one of claims 1 to 3, characterized in that, for a production batch comprising several identical high-pressure hydraulic lines, the specific adaptation of the basic program (B) stored in the radial press (1) taking into account the configuration of the pressing tool (6) captured when the pressing jaws (7) are placed on the press sleeve (5), is carried out during the first pressing operation of the production batch and is retained for subsequent pressing operations.

6. Method according to one of claims 1 to 5, characterized in that the specific adaptation of the basic program (B) stored in the radial press (1) consists in determining the specific final dimension for the force closure of the press tool (6) without influencing the force-displacement characteristic curve passed through up to that point.

7. Method according to one of claims 1 to 5, characterized in that the specific adaptation of the basic program (B) stored in the radial press (1) consists in determining the specific final dimension for the force closure of the pressing tool (6) while simultaneously influencing the force-displacement characteristic curve passed through up to that point.

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