Device and method for pressure measurement during fixture hardening

Abstract

The present invention relates to a tool for fixture hardening of a preferably rotationally symmetrical component, comprising at least one hardening mandrel designed to be inserted into an opening of the component during the fixture hardening process, and at least one pressure jaw designed to exert radial pressure on the component from the outside during the fixture hardening process. The at least one pressure jaw and / or the hardening mandrel includes at least one sensor, preferably a pressure sensor, by means of which a force applied by the tool to the component during the fixture hardening process can be measured. The instrumentation of the tool allows the forces acting on the component to be determined directly and immediately.

Description

[0001] The present invention relates to a device and a method for pressure measurement during fixture hardening.

[0002] Fixture hardening is used, for example, in the aerospace industry to meet the constantly increasing demands on materials and quality. In this hardening process, very high forces are applied to the component from the outside via mechanical fixtures during quenching in a defined and reproducible coolant flow, thus holding it in shape. The fixtures used are always adapted to the outer contour of the workpiece.

[0003] However, with conventional fixture hardening, the forces acting on the component can only be determined imprecisely.

[0004] The force exerted radially on the workpiece via the tool during the quenching process, for example, is generated by a hydraulic cylinder and controlled by a regulator. Typically, a total force in kN at the tool and a pulsing of the force can be set. Measurements of this force and the pulse, directly or indirectly, are conventionally performed exclusively via measurements of the hydraulics and their associated parameters.

[0005] The hydraulic cylinder's direction of action is vertical, while the force acts on the workpiece in a horizontal direction. The directed application of the force radially to the component is achieved within the tool by means of a mechanical system. The force is distributed across outer jaws (press segments) that bear against the component and transmit the force.

[0006] The direction of the force generated by the hydraulics is mechanically changed from vertical to horizontal for the application, and the total force is distributed across individual jaws or segments that have radial contact with the component from the outside.

[0007] According to current technology, the forces between a hardening mandrel and the workpiece are only measured indirectly after quenching, at the end of the hardening process. For example, only the ejection force is measured, i.e., the force required to release the workpiece from the hardening mandrel. Acoustic measurements of the ejection process are also known.

[0008] In conventional fixture hardening, the radially acting force of a single outer jaw on the workpiece does not correspond to the total force that can be set by the control system.

[0009] The mechanical transmission of force from the generating hydraulic cylinder to the point of action - radially outside on the component - and the distribution of force across multiple outer jaws cannot be measured using known methods and therefore cannot be documented in detail, traced, or evaluated for assessing process and component quality.

[0010] The following parameters, for example, cannot be considered during conventional fixation: • The magnitude of the force acting on the component per radial segment • Start date of printing training • Duration of contact between outer jaws and workpiece • Potential loss of force in the tool

[0011] Force measurements in the hardening mandrel during quenching are also not possible with conventional fixture hardening.

[0012] Furthermore, in conventional hardening processes, forces between the hardening mandrel and the workpiece cannot be measured during the quenching process, but only indirectly in the cold, hardened state. Therefore, no information is available about the pressure between the workpiece and the hardening mandrel, and thus no information is available about the straightening process in the hardening press.

[0013] Against this background, the present invention is based on the objective of mitigating or even completely eliminating the disadvantages of the prior art.

[0014] The present invention is specifically designed to provide a means of directly measuring forces acting on the component within the tool during the press hardening and quenching process, i.e., during the straightening process. Furthermore, it is preferable to make measurable forces acting radially on the outside of the workpiece and forces between the hardening mandrel and the workpiece.

[0015] This problem is solved by the device with the features of claim 1 and the further subject matter of the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims.

[0016] A tool for fixture hardening of a preferably rotationally symmetrical component is provided, comprising at least one hardening mandrel designed to be inserted into an opening of the component during fixture hardening, and at least one pressure jaw designed to exert radial pressure on the component from the outside during fixture hardening, characterized in that the at least one pressure jaw and / or the hardening mandrel has at least one sensor, preferably a pressure sensor, by means of which a force applied by the tool to the component during fixture hardening can be measured.

[0017] In other words, the invention relates to a tool for carrying out a press hardening and quenching process for a preferably rotationally symmetrical workpiece, in particular for a gear, wherein the tool is designed to exert forces acting radially on the workpiece, and wherein the tool is equipped with one or more sensors for pressure measurement.

[0018] Using a tool according to the invention, forces within the tool can be measured during a press hardening process. Forces acting radially on the workpiece and those acting within the hardening mandrel can also be measured. The measurement can be performed via a sensor integrated into the tool's mechanism and / or the hardening mandrel.

[0019] According to the invention, the tool is thus instrumented, i.e., provided with sensors for monitoring a process carried out by means of the tool.

[0020] In a tool according to the invention, the at least one clamping jaw is preferably multi-part, preferably at least two-part. Preferably, several clamping jaws are provided, which are preferably arranged on a common circular path and surround the component.

[0021] Preferably, the at least one pressure jaw has a first part which is designed to come into contact with the component, and a second part, preferably arranged radially outside the first part.

[0022] According to one embodiment, the at least one clamping jaw is equipped with at least two sensors arranged vertically one above the other in such a way that the sensors can detect any tilting of the component relative to the clamping jaw. Tilting of the component is indicated by different pressure values ​​detected by the sensors. When the component is correctly aligned, the sensors deliver identical or substantially identical values.

[0023] According to one embodiment, the sensor or sensors at least partially penetrate the first part and / or the second part of the at least one clamping jaw. The sensors are preferably pressure transducers.

[0024] To enable precise measurement of the force applied to the component, the at least one sensor is preferably connected to a contact surface of the clamping jaw by means of a frictional connection without force bypass. This contact surface is designed to make contact with the component. This ensures that the force detected by the sensor corresponds to the force actually applied to the component by the tool or clamping jaw.

[0025] Alternatively or additionally, the hardening mandrel of a tool according to the invention can have at least one sensor which is designed to detect the forces applied in the radial direction from the hardening mandrel to the component and / or the forces applied by the component in the radial direction to the hardening mandrel.

[0026] In other words, the hardening mandrel can be instrumented with at least one sensor, analogous to the above statements regarding the pressure jaw.

[0027] In this case, the hardening mandrel is preferably multi-part, preferably at least two-part.

[0028] The hardening mandrel preferably comprises a first part, which is designed to come into contact with the component, and a second part, preferably arranged radially inside the first part. The parts are preferably separable. The same applies to a corresponding design of a clamping jaw.

[0029] The clamping jaws of the tool are preferably identical to each other.

[0030] In the case of the hardening mandrel, the sensor(s) also penetrate the first part and / or the second part at least partially.

[0031] Furthermore, the present invention relates to a method for pressure measurement during fixture hardening, wherein preferably a tool according to the present invention is used, comprising the steps: - Inserting a component into a tool for fixture hardening, wherein a hardening mandrel of the tool is inserted into an opening of the component and at least one pressure jaw of the tool exerts pressure in a radial direction inwards on the component, - Performing a fixture hardening process while simultaneously detecting the forces exerted by the tool by means of at least one corresponding sensor arranged in or on the hardening mandrel and / or the at least one pressure jaw.

[0032] The sensor (or sensors) is preferably an online measuring pressure sensor designed to detect pressure during the operation of the tool, preferably continuously.

[0033] Furthermore, the present invention relates to the use of a tool according to the present invention and / or a method according to the present invention for the manufacture of an aircraft and / or a component thereof, in particular a gear.

[0034] In other words, aspects of the present invention can be described as follows: For example, one or more pressure sensors are integrated into the pressing mechanism of the tool. Alternatively or additionally, one or more pressure sensors are integrated into the hardening mandrel of the tool.

[0035] The tool is preferably divided into two or more parts / divisible or separated / separable and is preferably connected to one or more sensors.

[0036] If forces are exerted through the split / divisible tool, these must be guided through the sensors and can be measured during quenching.

[0037] An instrumented tool according to the invention is preferably constructed without force bypass (forces that are not conducted through the sensor).

[0038] The previously unmeasurable forces acting directly on the workpiece can be measured using the present invention. The force profile can be recorded, thus enabling process monitoring. For example, pulsation can be measured and compared with a target value. Since the applied force is usually crucial for the process in fixture hardening, the process can be controlled and the process management optimized.

[0039] The invention thus makes it possible to regulate the radial pressing force acting on the component / workpiece during the fixture hardening process, which is not meaningfully possible without feedback (measured force).

[0040] Instrumenting the outer jaws allows for the detection of potential force loss in the tool due to mechanical stress. The robustness and repeatability of the process can be evaluated based on the measurement data. Furthermore, the measurements enable data-driven maintenance of the tool.

[0041] The invention further enables the measurement of tilting (cylindricity) of the component during the process by means of outer jaws of the tool according to the invention, which are each equipped, for example, with two sensors arranged vertically one above the other.

[0042] Furthermore, the invention enables the creation of reference curves and thus the verification of the functionality of the tool after maintenance, modifications or new designs.

[0043] The transfer of processes from tool to tool (e.g., tools from different manufacturers) can also be carried out and evaluated using objective data based on measurements and reference curves.

[0044] It should be noted here that the terms "ein" and "eine" do not necessarily refer to exactly one of the elements, although this is a possible interpretation, but can also denote a plurality of elements. Likewise, the use of the plural also includes the presence of the element in question in the singular, and conversely, the singular also includes several of the elements in question.

[0045] Furthermore, all features of the invention described herein can be combined with one another or claimed separately from one another; the disclosure is therefore not limited to explicitly mentioned combinations of features.

[0046] Further details and advantages of the invention will be explained in more detail with reference to the exemplary embodiments shown in the drawing.

[0047] They show: Fig. 1: Exemplary contact surfaces of a pressure jaw of a tool according to the invention; Fig. 2: a pressure jaw of a tool according to the invention; Fig. 3: another pressure jaw of a tool according to the invention; Fig. 4: a hardening mandrel of a tool according to the invention; and Fig. 5: a control loop in which the sensor values ​​determined by means of a tool according to the invention can be used.

[0048] Fig. Figure 1 shows the pressing mechanism of a tool according to the invention. Panels 1a) to 1c) show pressing jaws with different contact geometries. Panel 1a) shows a smooth contact surface 1, panel 1b) shows a contact surface 2 with cooling channels, and panel 1c) shows a contact surface 3 with a step 4.

[0049] For the instrumentation of the in Fig. In the outer jaws shown in section 1, the pressure jaws are divided and one or more sensors are installed.

[0050] As in Fig. Figure 2 shows an instrumented pressure jaw according to the invention, which transmits forces by contact with the workpiece, is divided into a first part 5 and a second part 6 and connected to a pressure sensor 7 without force shunt.

[0051] The pressure sensor 7 penetrates the first part 5 and the second part 6. The force acting on the component, per pressure jaw, can thus be measured without distortion.

[0052] Fig. Figure 3 shows an instrumented pressure jaw according to the invention, which transmits forces through contact with the workpiece and has a first part 5 and a second part 6.

[0053] The clamping jaw is equipped with two vertically arranged pressure sensors 7. The design ensures a connection between the contact surface and the pressure sensors 7 without force bypass.

[0054] The force acting on the component per pressure jaw can thus be measured. By using two sensors 7 in a vertically arranged pressure jaw, as shown, tilting of the component due to resulting pressure differences can be measured.

[0055] Fig. Figure 4 shows a hardening mandrel 8 with an integrated sensor 7. The hardening mandrel 8 has a first part 9 and a second part 10, which are at least partially penetrated by the sensor. In this example as well, the connection between the contact surface and the sensor 7 is without a force shunt.

[0056] Fig. Figure 5 shows a general form of a control loop with a measuring device and feedback of the measured force. The values ​​measured by means of a tool according to the invention can be used, for example, within such a control loop to adjust or optimize the settings of the fixture hardening process, preferably during the ongoing process.

Claims

[1] Tool for fixture hardening of a preferably ring-shaped component, comprising at least one hardening mandrel designed to be inserted into an opening of the component during fixture hardening, and at least one pressure jaw designed to exert radial pressure on the component from the outside during fixture hardening, characterized by that the at least one pressure jaw and / or the hardening mandrel has at least one sensor, preferably a pressure sensor, by means of which a force applied by the tool to the component during fixture hardening can be measured. [2] Tool according to claim 1, characterized by that the at least one pressure jaw is multi-part, preferably at least two-part. [3] Tool according to claim 2, characterized by, that the at least one pressure jaw has a first part which is designed to come into contact with the component and a second part, preferably arranged radially outside the first part. [4] Tool according to any one of the preceding claims, characterized by that the at least one pressure jaw has at least two sensors which are arranged vertically one above the other in such a way that a tilting of the component relative to the pressure jaw can be detected by means of the sensors. [5] Tool according to one of claims 3 or 4, characterized by that the sensor or sensors penetrate at least partially the first part and / or the second part. [6] Tool according to any one of the preceding claims, characterized by, that the at least one sensor is positively connected without force bypass to a contact surface of the pressure jaw which is designed to come into contact with the component. [7] Tool according to any one of the preceding claims, characterized by that the hardening mandrel has at least one sensor designed to detect the forces applied radially from the hardening mandrel to the component and / or the forces applied radially from the component to the hardening mandrel. [8] Tool according to any one of the preceding claims, characterized by that the hardening mandrel is multi-part, preferably at least two-part. [9] Tool according to claim 8, characterized by , that the hardening mandrel has a first part which is designed to come into contact with the component, and a second part, preferably arranged radially inside the first part. [10] Tool according to any one of claims 7 to 9, characterized by that the sensor or sensors penetrate at least partially the first part and / or the second part. [11] Method for measuring pressure during fixture hardening, preferably using a tool according to one of claims 1 to 10, comprising the steps: - Inserting a component into a tool for fixture hardening, wherein a hardening mandrel of the tool is inserted into an opening of the component and at least one pressure jaw of the tool exerts pressure in a radial direction inwards on the component, - Performing a fixture hardening process while simultaneously detecting the forces exerted by the tool by means of at least one corresponding sensor arranged in or on the hardening mandrel and / or the at least one pressure jaw. [12] Method according to claim 11, wherein the sensor is an online measuring pressure sensor designed to detect pressure during the operation of the tool, preferably continuously. [13] Use of a tool according to any one of claims 1 to 10 and / or a method according to any one of claims 11 or 12, for manufacturing an aircraft and / or a component thereof, in particular a gear.

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