Part stress deformation analysis method, electronic equipment and storage medium during mold forced release

Abstract

The present invention discloses a method for analyzing the stress deformation of a part during forced demolding of a mold, an electronic device, and a storage medium. The method comprises: establishing a virtual simulation model, the virtual simulation model comprising a virtual simulation model of a part for simulating a part and a virtual simulation model of a demolding tool for simulating a demolding tool, the demolding tool is used to perform a forced demolding operation on the part, and the virtual simulation model of the part is obtained by simulating the material parameters of the part at the demolding temperature; performing a forced demolding simulation operation on the virtual simulation model of the part by the demolding tool simulation model; obtaining the deformation parameters of the virtual simulation model of the part after the forced demolding simulation operation is performed, if the deformation parameters meet the preset no plastic deformation risk condition, it is judged that there is no plastic deformation risk, otherwise it is judged that there is a plastic deformation risk. The present invention simulates the part and the demolding tool, and simulates the forced demolding operation performed by the demolding tool, so as to judge whether there is a plastic deformation risk when the part performs the forced demolding operation through the simulation results.

Description

Technical Field

[0001] The invention relates to the technical field of automobiles, and in particular to a method for analyzing the stress deformation of parts during forced release of a mold, electronic equipment and a storage medium. Background Art

[0002] Injection molded parts often have local features that are undercut, which makes it impossible to demold properly. Generally, mold structures such as inclined top sliders are used to solve this problem. However, sometimes when mold structures such as inclined top sliders cannot be arranged, if the angle of the undercut is within a suitable range, the mold will use a forced demolding method. That is, a pull hook is designed at the mold position corresponding to the feature area where the part cannot be demolded. First, the part is pulled outward with the pull hook until the undercut feature is completely offset from the mold, and then the part is ejected. The limitation of this method is that the undercut amount of the feature cannot be too large, otherwise the pull hook will be pulled out too much, which will easily cause stress concentration in the part and produce white marks or even local fractures.

[0003] Taking the automotive interior parts as an example, there will be many undercut features on the main body of the auxiliary instrument panel without splitting the frame. The auxiliary instrument panel of the car is generally fixed to the iron bracket of the channel floor of the car body with 6 screws. In order to maintain the appearance, each screw point on the auxiliary instrument panel is an undercut pit structure, and the forced stripping method is usually adopted. The existing forced stripping feasibility analysis is based on the experience of the mold factory. Generally, the angle that the surface pulled outward around the vertex cannot exceed during forced stripping is used as the standard, and there is no sufficient theoretical analysis. A special situation encountered in actual work is that the body bracket is used as a car frame component, and different models of the same platform usually choose to share the body bracket. If the auxiliary instrument panel of the previous model is fully equipped with armrests, the Z-direction height is relatively high and the rear panel is split, the screw points at the rear end of the auxiliary instrument panel will be arranged relatively high, which is conducive to the modality of the auxiliary instrument panel; and the subsequent models may need to add a low-equipped auxiliary instrument panel without armrests, low height, and the rear panel cannot be split due to cost constraints. At this time, the forced stripping of the screw pit feature at the rear end of the auxiliary instrument panel is more complicated. The mold needs to pull the side panels on both sides of the auxiliary instrument panel outward for forced release. However, because the rear panel is not split, it is equivalent to a three-sided enclosed structure. Pulling the side panels outward will more easily cause local stress concentration, resulting in white marks, or even cracks or breaks. The higher the screw point and the closer it is to the rear end, the more serious the problem. The empirical judgment of the prior art can only be applied to the judgment of a single local direction. If it involves this three-sided enclosed structure, that is, forced release in two directions at the same time, the analysis method of the prior art will be completely invalid. Summary of the invention

[0004] Based on this, it is necessary to provide a method for analyzing the stress and deformation of parts during forced release of a mold, an electronic device and a storage medium in order to address the technical problems of the prior art.

[0005] The present invention provides a method for analyzing the stress deformation of parts during forced release of a mold, comprising:

[0006] Establishing a virtual simulation model, the virtual simulation model includes a part virtual simulation model for simulating the part and a demoulding tool virtual simulation model for simulating the demoulding tool, the demoulding tool is used to perform a forced demoulding operation on the part, and the part virtual simulation model is obtained by simulating the material parameters of the part at the demoulding temperature;

[0007] Executing a forced demoulding simulation operation of the demoulding tooling simulation model on the part virtual simulation model;

[0008] Obtain deformation parameters of the part virtual simulation model after executing the forced stripping simulation operation, and determine whether there is a risk of plastic deformation when executing the forced stripping operation according to the deformation parameters.

[0009] Furthermore, the performing of the forced demoulding simulation operation of the demoulding tooling simulation model on the part virtual simulation model specifically includes:

[0010] Determine the connection position between the demoulding tooling simulation model and the part virtual simulation model;

[0011] Determine the demoulding tooling simulation stroke of the demoulding tooling simulation model;

[0012] The demoulding tooling simulation model is controlled to be at the connection position, and the part virtual simulation model is pulled to move the demoulding tooling simulation stroke.

[0013] Furthermore, the step of determining the demoulding tooling simulation stroke of the demoulding tooling simulation model specifically includes:

[0014] Get the displacement of the demoulding tooling pulling the part outward when performing the forced demoulding operation;

[0015] The demoulding tooling simulation stroke of the demoulding tooling simulation model is determined according to the displacement.

[0016] Furthermore, the step of obtaining deformation parameters of the virtual simulation model of the part after the forced stripping simulation operation is performed specifically includes:

[0017] After obtaining the virtual simulation model of the part and executing the forced stripping simulation operation, the deformation parameters of the concerned area are preset.

[0018] Furthermore, the deformation parameter includes a strain of a preset area of ​​interest.

[0019] Furthermore, judging whether there is a risk of plastic deformation when performing a forced release operation on the part according to the deformation parameter specifically includes:

[0020] If the strain of the preset focus area is less than the preset strain threshold, it is determined that there is no risk of plastic deformation; otherwise, it is determined that there is a risk of plastic deformation.

[0021] Furthermore, the deformation parameter includes stress of a preset area of ​​interest.

[0022] Furthermore, judging whether there is a risk of plastic deformation when performing a forced release operation on the part according to the deformation parameter specifically includes:

[0023] If the stress of the preset focus area is less than the preset stress threshold, it is determined that there is no risk of plastic deformation; otherwise, it is determined that there is a risk of plastic deformation.

[0024] The present invention provides an electronic device, comprising:

[0025] at least one processor; and,

[0026] a memory communicatively connected to at least one of the processors; wherein,

[0027] The memory stores instructions that can be executed by at least one of the processors, and the instructions are executed by at least one of the processors so that at least one of the processors can execute the method for analyzing the stress and deformation of parts during forced mold release as described above.

[0028] The present invention provides a storage medium, which stores computer instructions. When a computer executes the computer instructions, it is used to execute all steps of the method for analyzing the stress and deformation of parts during forced release of the mold as described above.

[0029] The present invention uses the material parameters of the parts at the demoulding temperature for placement, thereby improving the accuracy of the part simulation model. By simulating the parts and the demoulding tooling, the demoulding tooling performs a forced demoulding operation and simulates it, thereby judging whether the parts have a risk of plastic deformation when performing the forced demoulding operation through the simulation results. The present invention can make a well-founded judgment on the feasibility of forced demoulding of the mold in the data design stage, breaking through the existing deficiencies of judging the feasibility of forced demoulding in one direction based on experience. And the forced demoulding situation of the entire part can be analyzed as a whole, breaking through the locality and one-sidedness of the traditional judgment method. It can also verify the effectiveness of the new solution, provide effective guidance for the design, and form a closed-loop processing of the problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a flowchart of a method for analyzing the stress and deformation of parts during forced release of a mold;

[0031] Figure 2 It is a working flow chart of a method for analyzing the stress and deformation of parts during forced release of a mold in one embodiment of the present invention;

[0032] Figure 3 The following is a working flow chart of a method for analyzing the stress and deformation of parts during forced release of a mold according to the best embodiment of the present invention;

[0033] Figure 4 The figure is a schematic diagram of the hardware structure of an electronic device of the present invention. DETAILED DESCRIPTION

[0034] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. The same components are represented by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the accompanying drawings, and the words "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0035] Embodiment 1

[0036] like Figure 1 The flowchart of the method for analyzing the stress deformation of parts during forced release of a mold according to the present invention is shown, comprising:

[0037] Step S101, establishing a virtual simulation model, wherein the virtual simulation model includes a part virtual simulation model for simulating a part and a demoulding tool virtual simulation model for simulating a demoulding tool, wherein the demoulding tool is used to perform a forced demoulding operation on the part, and the part virtual simulation model is obtained by simulating the material parameters of the part at the demoulding temperature;

[0038] Step S102, executing a forced demoulding simulation operation of the demoulding tooling simulation model on the part virtual simulation model;

[0039] Step S103, obtaining deformation parameters of the virtual simulation model of the part after the forced release simulation operation is performed, and judging whether there is a risk of plastic deformation of the part when the forced release operation is performed according to the deformation parameters.

[0040] Specifically, execute step S101 to establish a virtual simulation model. Specifically, a virtual simulation model of a part simulating a part and a virtual simulation model of a demolding tooling for simulating a demolding tooling can be established in Computer Aided Engineering (CAE). The demolding tooling is used to perform a forced demolding operation on the part. The forced demolding operation refers to pulling the part outward through the demolding tooling to a position where the undercut feature of the part is completely offset from the mold. The demolding tooling can be a hook. Because the failure risk at the demolding temperature needs to be simulated and analyzed, when establishing the part simulation model, the material parameters of the part at the demolding temperature are simulated. Material parameters include but are not limited to material density, Poisson's ratio, elastic modulus, yield strain, etc.

[0041] Then, step S102 performs a forced release simulation operation, that is, in CAE, the part simulation model is pulled outward through the demoulding tooling simulation model, until the undercut feature of the part simulation model is pulled to a preset forced release position.

[0042] Then, step S103 is executed to obtain deformation parameters of the virtual simulation model of the part in CAE, and determine whether there is a risk of plastic deformation based on the deformation parameters.

[0043] The present invention uses the material parameters of the parts at the demoulding temperature for placement, thereby improving the accuracy of the part simulation model. By simulating the parts and the demoulding tooling, the demoulding tooling performs a forced demoulding operation and simulates it, thereby judging whether the parts have a risk of plastic deformation when performing the forced demoulding operation through the simulation results. The present invention can make a well-founded judgment on the feasibility of forced demoulding of the mold in the data design stage, breaking through the existing deficiencies of judging the feasibility of forced demoulding in one direction based on experience. And the forced demoulding situation of the entire part can be analyzed as a whole, breaking through the locality and one-sidedness of the traditional judgment method. It can also verify the effectiveness of the new solution, provide effective guidance for the design, and form a closed-loop processing of the problem.

[0044] Embodiment 2

[0045] like Figure 2 The flowchart is a method for analyzing the stress and deformation of parts during forced release of a mold according to an embodiment of the present invention, comprising:

[0046] Step S201, establishing a virtual simulation model, wherein the virtual simulation model includes a part virtual simulation model for simulating the part and a demolding tool virtual simulation model for simulating the demolding tool, wherein the demolding tool is used to perform a forced demolding operation on the part, and the part virtual simulation model is obtained by simulating the material parameters of the part at the demolding temperature.

[0047] Step S202, determining the connection position between the demoulding tooling simulation model and the part virtual simulation model.

[0048] Step S203, determining the demoulding tooling simulation stroke of the demoulding tooling simulation model.

[0049] In one embodiment, determining the demoulding tooling simulation stroke of the demoulding tooling simulation model specifically includes:

[0050] Get the displacement of the demoulding tooling pulling the part outward when performing the forced demoulding operation;

[0051] The demoulding tooling simulation stroke of the demoulding tooling simulation model is determined according to the displacement.

[0052] Step S204, controlling the demoulding tooling simulation model at the connection position, and pulling the part virtual simulation model to move the demoulding tooling simulation stroke.

[0053] Step S205, after acquiring the virtual simulation model of the part to perform the forced release simulation operation, the deformation parameters of the focus area are preset, and whether there is a risk of plastic deformation when performing the forced release operation on the part is determined according to the deformation parameters.

[0054] In one embodiment, the deformation parameter includes a strain of a preset region of interest.

[0055] In one embodiment, judging whether there is a risk of plastic deformation when performing a forced release operation on the part according to the deformation parameter specifically includes:

[0056] If the strain of the preset focus area is less than the preset strain threshold, it is determined that there is no risk of plastic deformation; otherwise, it is determined that there is a risk of plastic deformation.

[0057] In one embodiment, the deformation parameter includes stress in a preset area of ​​interest.

[0058] In one embodiment, judging whether there is a risk of plastic deformation when performing a forced release operation on the part according to the deformation parameter specifically includes:

[0059] If the stress of the preset focus area is less than the preset stress threshold, it is determined that there is no risk of plastic deformation; otherwise, it is determined that there is a risk of plastic deformation.

[0060] Specifically, the preferred parts of this embodiment are: injection molded parts with undercut features, mold structures that cannot be arranged with inclined top sliders, and injection molded parts that require forced release. The manufacturing feasibility of injection molded parts is analyzed. A typical automotive part is a sub-instrument panel that has no split independent skeleton and requires local forced release. The virtual analysis method is used to analyze the stress and deformation of the sub-instrument panel when it is forced out of the mold, and to determine whether the parts have the risk of white marks or breakage due to excessive force during the forced release process. Identifying such problems in the early data design stage of the project and before the mold is opened can avoid more passive engineering changes and the resulting mold repair costs in the later stage. This embodiment is not limited to the feasibility analysis of the sub-instrument panel, and this method can be adopted in all cases where injection molded parts need to be forced out. The demolding tooling is preferably a draw hook.

[0061] This embodiment uses CAE virtual analysis of stress conditions. The difference from ordinary CAE analysis of stress conditions is that in step S201, the material-related performance parameters input into the virtual simulation model are at the demolding temperature, rather than the material parameters at room temperature. Because the failure risk at the demolding temperature needs to be simulated and analyzed, the density of the material at the demolding temperature in this working condition is 1.01e-6kg / mm^3, the Poisson's ratio is 0.4, the elastic modulus is about 650MPa, and the yield strain is about 2.0%. At the same time, the stress-strain curve of the nonlinear segment needs to be referenced.

[0062] Then, in step S202, the connection position between the demoulding tooling simulation model and the part virtual simulation model is determined, and the connection position is preferably the corresponding position of the undercut feature pulled by the demoulding tooling when performing a forced demoulding operation on the part in the part virtual simulation model.

[0063] Then, step S203 determines the simulation stroke of the demoulding tooling. Specifically, the displacement of the demoulding tooling pulling the part outward during strong demoulding is input into CAE. The displacement is the stroke of the demoulding tooling simulation model when performing the strong demoulding simulation operation. Based on the stroke, step S204 is executed to control the demoulding tooling simulation model at the connection position, and pull the part virtual simulation model to move the demoulding tooling simulation stroke. In step S205, the strain or stress of the part output by CAE under the displacement condition is obtained. Preferably, the final result is judged by judging whether the strain exceeds the yield limit of the material, and the yield limit of the material is the preset strain threshold. If the yield limit of the material is exceeded, the part has the risk of white printing or fracture, and corresponding measures need to be taken to make adjustments, such as changing the part structure. According to the CAE analysis results, an adjustment plan is formulated, and then the above steps can be re-executed, and the analysis and verification in CAE are analyzed. If the strain is lower than the yield limit of the material, it means that the change is effective. Some safety margins can be appropriately placed to accommodate the noise in actual production. In addition, it can also be judged whether the stress exceeds the preset stress threshold to determine whether there is a risk of plastic deformation. The specific stress threshold is determined by the yield limit of the material.

[0064] This embodiment uses the material parameters of the parts at the demoulding temperature for placement, thereby improving the accuracy of the part simulation model. In addition, the position and displacement of the forced stripping simulation operation are consistent with the actual forced stripping operation, which improves the accuracy of the forced stripping operation placement. By simulating the parts and the demoulding tooling, the forced stripping operation performed by the demoulding tooling is simulated, so as to judge whether the parts have the risk of plastic deformation when performing the forced stripping operation by the simulation results. This embodiment can make a well-founded judgment on the feasibility of mold forced stripping in the data design stage, breaking through the existing deficiency of judging the feasibility of one-way forced stripping only by experience. And the forced stripping situation of the entire part can be analyzed as a whole, breaking through the locality and one-sidedness of the traditional judgment method. It is also possible to verify the effectiveness of the new scheme, provide effective guidance for the design, and form a closed-loop processing of the problem.

[0065] like Figure 3 The flowchart of the method for analyzing the stress deformation of parts during forced release of a mold in the best embodiment of the present invention is shown, comprising:

[0066] Step S301, determining the demoulding tooling position;

[0067] Step S302, CAE calculation to determine the tooling stroke;

[0068] Step S303, CAE simulation of the tooling movement during strong stripping;

[0069] Step S304, confirming the boss displacement and the plastic deformation of the area of ​​interest;

[0070] Step S305, if passed, then end, otherwise change the structure.

[0071] The CAE analysis method of this embodiment is actually applied in the design process of the auxiliary instrument panel to determine whether forced mold release is feasible in the early stage of design.

[0072] This embodiment can make a well-founded judgment on the feasibility of forced release of the mold in the data design stage, breaking through the deficiency of the prior art that only judges the feasibility of forced release in one direction based on experience. It can also make an overall analysis of the forced release situation of the entire part, breaking through the locality and one-sidedness of the judgment method of the prior art. It can also verify the effectiveness of the new solution, provide effective guidance for the design, and form a closed-loop problem handling.

[0073] Embodiment 3

[0074] like Figure 4 The figure shows a hardware structure diagram of an electronic device of the present invention, including:

[0075] at least one processor 401; and,

[0076] A memory 402 is communicatively connected to at least one of the processors 401; wherein,

[0077] The memory 402 stores instructions that can be executed by at least one of the processors, and the instructions are executed by at least one of the processors so that at least one of the processors can execute the method for analyzing the stress and deformation of parts during forced mold release as described above.

[0078] Figure 4 A processor 401 is taken as an example.

[0079] The electronic device may further include: an input device 403 and a display device 404 .

[0080] The processor 401, the memory 402, the input device 403 and the display device 404 may be connected via a bus or other means, and the figure takes the connection via a bus as an example.

[0081] The memory 402 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as program instructions / modules corresponding to the method for analyzing the stress and deformation of parts during forced release of the mold in the embodiment of the present application, for example, Figure 1The processor 401 executes various functional applications and data processing by running the non-volatile software programs, instructions and modules stored in the memory 402, that is, the method for analyzing the stress and deformation of parts during forced release of the mold in the above embodiment is implemented.

[0082] The memory 402 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created according to the use of the method for analyzing the stress and deformation of parts during forced mold release, etc. In addition, the memory 402 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 402 may optionally include a memory remotely arranged relative to the processor 401, and these remote memories may be connected to a device for executing the method for analyzing the stress and deformation of parts during forced mold release via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0083] The input device 403 can receive user clicks and generate signal inputs related to user settings and function control of the part force deformation analysis method during mold forced release. The display device 404 can include display devices such as a display screen.

[0084] The one or more modules are stored in the memory 402, and when being executed by the one or more processors 401, the method for analyzing the stress and deformation of parts during forced mold release in any of the above method embodiments is executed.

[0085] The present invention uses the material parameters of the parts at the demoulding temperature for placement, thereby improving the accuracy of the part simulation model. By simulating the parts and the demoulding tooling, the demoulding tooling performs a forced demoulding operation and simulates it, thereby judging whether the parts have a risk of plastic deformation when performing the forced demoulding operation through the simulation results. The present invention can make a well-founded judgment on the feasibility of forced demoulding of the mold in the data design stage, breaking through the existing deficiencies of judging the feasibility of forced demoulding in one direction based on experience. And the forced demoulding situation of the entire part can be analyzed as a whole, breaking through the locality and one-sidedness of the traditional judgment method. It can also verify the effectiveness of the new solution, provide effective guidance for the design, and form a closed-loop processing of the problem.

[0086] An embodiment of the present invention provides a storage medium, wherein the storage medium stores computer instructions. When a computer executes the computer instructions, the storage medium is used to execute all steps of the method for analyzing the stress and deformation of a part during forced mold release as described above.

[0087] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for analyzing the stress and deformation of parts during forced release of a mold, characterized in that: include: Establishing a virtual simulation model, the virtual simulation model includes a part virtual simulation model for simulating the part and a demoulding tool virtual simulation model for simulating the demoulding tool, the demoulding tool is used to perform a forced demoulding operation on the part, and the part virtual simulation model is obtained by simulating the material parameters of the part at the demoulding temperature; Executing a forced demoulding simulation operation of the demoulding tooling simulation model on the part virtual simulation model; Obtaining deformation parameters of the virtual simulation model of the part after the forced stripping simulation operation is performed, and judging whether there is a risk of plastic deformation when the part is subjected to the forced stripping operation according to the deformation parameters; The performing of the forced demoulding simulation operation of the demoulding tooling simulation model on the part virtual simulation model specifically includes: Determine the connection position between the demoulding tooling simulation model and the part virtual simulation model; Determine the demoulding tooling simulation stroke of the demoulding tooling simulation model; The demoulding tooling simulation model is controlled to be at the connection position, and the part virtual simulation model is pulled to move the demoulding tooling simulation stroke.

2. The method for analyzing the stress and deformation of parts during forced mold release according to claim 1, characterized in that: Determining the demoulding tooling simulation stroke of the demoulding tooling simulation model specifically includes: Get the displacement of the demoulding tooling pulling the part outward when performing the forced demoulding operation; The demoulding tooling simulation stroke of the demoulding tooling simulation model is determined according to the displacement.

3. The method for analyzing the stress and deformation of parts during forced mold release according to claim 1, characterized in that: The step of obtaining deformation parameters of the virtual simulation model of the part after the forced stripping simulation operation is performed specifically includes: After obtaining the virtual simulation model of the part and executing the forced stripping simulation operation, the deformation parameters of the concerned area are preset.

4. The method for analyzing the stress and deformation of parts during forced mold release according to claim 3 is characterized in that: The deformation parameter includes a strain of a preset area of ​​interest.

5. The method for analyzing the stress and deformation of parts during forced mold release according to claim 4 is characterized in that: The step of judging whether there is a risk of plastic deformation when performing a forced release operation on the part according to the deformation parameter specifically includes: If the strain of the preset focus area is less than the preset strain threshold, it is determined that there is no risk of plastic deformation; otherwise, it is determined that there is a risk of plastic deformation.

6. The method for analyzing the stress and deformation of parts during forced mold release according to claim 3, characterized in that: The deformation parameters include stress in a preset area of ​​interest.

7. The method for analyzing the stress and deformation of parts during forced mold release according to claim 6, characterized in that: The step of judging whether there is a risk of plastic deformation when performing a forced release operation on the part according to the deformation parameter specifically includes: If the stress of the preset focus area is less than the preset stress threshold, it is determined that there is no risk of plastic deformation; otherwise, it is determined that there is a risk of plastic deformation.

8. An electronic device, characterized in that: include: at least one processor; as well as, a memory communicatively connected to at least one of the processors; wherein, The memory stores instructions that can be executed by at least one of the processors, and the instructions are executed by at least one of the processors so that at least one of the processors can execute the method for analyzing the stress and deformation of parts during forced mold release as described in any one of claims 1 to 7.

9. A storage medium, characterized in that: The storage medium stores computer instructions, and when the computer executes the computer instructions, it is used to execute all steps of the method for analyzing the stress and deformation of parts during forced release of the mold as described in any one of claims 1 to 7.

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