Press forming device

Abstract

The present application provides a stamping forming device capable of correcting the gap of a die and performing stable processing. The stamping forming device comprises a punch, a die having an inclined surface inclined toward a hollow portion for insertion of the punch, a die plate holding the die, a blank holder member having a pressing surface opposite to the inclined surface of the die, a die load sensor detecting a load in a stamping direction, a load in a first direction perpendicular to the stamping direction, and a load in a second direction perpendicular to the stamping direction and the first direction, a control unit calculating a vertical resistance of the die based on the load in the stamping direction, the load in the first direction, and the load in the second direction detected by the die load sensor, and calculating a gap correction amount between the die and the blank holder member based on the vertical resistance of the die, a first driving unit moving the die along the stamping direction based on the gap correction amount, and a second driving unit driving the punch along the stamping direction.

Description

Technical Field

[0001] This invention relates to a stamping forming apparatus. Background Technology

[0002] When metal materials are bent or drawn through stamping, production is usually carried out based on pre-set processing conditions according to the material or environmental changes.

[0003] For example, Patent Document 1 discloses a stamping processing condition setting device that sets processing conditions in a manner that can obtain the specified stamping quality even when there are deviations in the material or sheet thickness.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 7-266100 Summary of the Invention

[0007] According to one aspect of the present invention, a stamping forming apparatus processes a plate-shaped workpiece. The stamping forming apparatus comprises: a punch that moves along a stamping direction; a die having a hollow portion into which the punch is inserted and an inclined surface inclined toward the hollow portion; a die plate holding the die; a blank holder disposed between the punch and the die and having a pressing surface facing the inclined surface of the die; a die load sensor that detects the load generated on the inclined surface of the die as loads in three directions: load in the stamping direction, load in a first direction perpendicular to the stamping direction, and load in a second direction perpendicular to both the stamping direction and the first direction; a control unit that calculates the vertical resistance of the die based on the loads in the stamping direction, the first direction, and the second direction detected by the die load sensor, and calculates a clearance correction amount between the die and the blank holder based on the vertical resistance of the die; a first drive unit that moves the die along the stamping direction based on the clearance correction amount; and a second drive unit that drives the punch along the stamping direction. Attached Figure Description

[0008] Figure 1 This is a schematic diagram showing the stamping forming apparatus of Embodiment 1.

[0009] Figure 2 It is shown Figure 1 A schematic diagram of the upper dead center state of the punch in a stamping forming device.

[0010] Figure 3 It is shown Figure 1 A schematic diagram of the bottom dead center state of the punch in a stamping forming device.

[0011] Figure 4 It is Figure 3 The image is obtained by magnifying the region R1.

[0012] Figure 5 yes Figure 1 A top view of the die and die plate of the stamping forming device.

[0013] Figure 6 Yes Figure 1 The flowchart illustrates the gap correction process of the stamping forming device.

[0014] Figure 7 This is a graph showing the relationship between the vertical resistance of the die and the processing time from the start of forming.

[0015] Figure 8 This is a graph showing the relationship between the vertical resistance of the die and the processing time from the start of forming when the impulse difference is within ±20%.

[0016] Figure 9 It is a graph showing the relationship between the impulse difference and the clearance correction.

[0017] Figure 10 It is a graph showing the relationship between the load applied to the punch and the processing time from the start of forming.

[0018] Figure 11 It is a graph showing the relationship between the load applied to the punch and the processing time from the start of forming when the impulse difference is within ±20%.

[0019] Figure 12 It is a graph showing the relationship between the impulse difference and the correction amount of the injection.

[0020] Explanation of reference numerals in the attached figures

[0021] 1. Punch

[0022] 2. Stamping Die

[0023] 2a Inclined plane

[0024] 2c~2f Stamping Die Parts

[0025] 4. Punching template

[0026] 5 workpieces

[0027] 11 Servo Motor (Second Drive Unit)

[0028] 13 Punch Load Sensor

[0029] 14, 14cc~14f Die Load Sensor

[0030] 15 First gap sensor

[0031] 16, 16a~16d Second gap sensor

[0032] 18. Actuator (First Drive Unit)

[0033] 100 Stamping forming device. Detailed Implementation

[0034] (The process of completing this invention)

[0035] When performing bending or deep drawing processes using a stamping forming apparatus, processing conditions are pre-set, taking into account the influence of material factors such as the material composition or thickness of the metal being processed, as well as environmental factors of the stamping forming apparatus. Processing conditions can be determined, for example, based on experience, experiments, or simulations. Since the influence of material or environmental factors is often difficult to predict, various studies have been conducted on methods for controlling processing conditions to account for their effects.

[0036] For example, Patent Document 1 discloses a method that pre-determines the relationship between physical quantities such as the shape of the stamping raw material (metal material) and an appropriate blank holder load (appropriate stamping processing conditions), and determines an appropriate blank holder amount based on this relationship and the actual physical quantities.

[0037] In the stamping condition setting device described in Patent Document 1, there is room for improvement in terms of processing stability. Specifically, in the stamping condition setting device described in Patent Document 1, due to unpredictable variations, the following problem exists: it is impossible to properly maintain the clearance between the blank holder and the die, thus making stable processing impossible. Unpredictable variations refer to deviations caused by the characteristics of the material of the workpiece or environmental changes caused by temperature. Unpredictable variations also refer to environmental changes related to the stamping forming apparatus and the die, such as forming speed, bottom dead center accuracy, die machining dimensional accuracy, blank holder force, clearance between the blank holder and the die, die surface roughness, or lubrication between the workpiece and the die. Such environmental changes are difficult to predict, therefore, the following problem exists: it is difficult to pre-determine an appropriate blank holder load, and it is difficult to maintain the clearance between the blank holder and the die at an appropriate value.

[0038] Therefore, the inventors studied a stamping apparatus capable of correcting the clearance for stable processing and completed the following invention. The present invention provides a stamping apparatus capable of correcting the clearance of a die for stable processing.

[0039] The first aspect of the present invention provides a stamping forming apparatus for processing plate-shaped workpieces. The stamping forming apparatus comprises: a punch that moves along the stamping direction; a die having a hollow portion for insertion of the punch and an inclined surface inclined toward the hollow portion; a die plate holding the die; a blank holder disposed between the punch and the die and having a pressing surface facing the inclined surface of the die; a die load sensor that detects the load generated on the inclined surface of the die as loads in three directions: load in the stamping direction, load in a first direction perpendicular to the stamping direction, and load in a second direction perpendicular to both the stamping direction and the first direction; a control unit that calculates the vertical resistance of the die based on the loads in the stamping direction, the first direction, and the second direction detected by the die load sensor, and calculates a clearance correction amount between the die and the blank holder based on the vertical resistance of the die; a first drive unit that moves the die along the stamping direction based on the clearance correction amount; and a second drive unit that drives the punch along the stamping direction.

[0040] With this structure, the clearance correction between the blank holder and the die can be calculated based on the vertical resistance of the die, thus providing a stamping forming device that can maintain the clearance appropriately and perform stable processing.

[0041] In the stamping apparatus of the second aspect of the present invention, the clearance correction amount may also be calculated based on the difference between the impulse calculated based on the vertical resistance of the die and the processing time under appropriate clearance and the impulse calculated based on the vertical resistance of the die and the processing time during processing.

[0042] This structure allows for a more accurate calculation of the gap correction amount.

[0043] The stamping apparatus of the third embodiment of the present invention may further include a punch load sensor for detecting the load of the punch applied along the stamping direction, a control unit for calculating the punch pressing correction amount based on the punch load detected by the punch load sensor, and a second drive unit for driving the punch based on the punch pressing correction amount.

[0044] This structure allows for the correction of the punch's feed amount, resulting in more stable processing.

[0045] In the stamping apparatus of the fourth embodiment of the present invention, the punch pressing correction amount may be calculated based on the difference between the punch load and processing time under the condition of appropriate pressing amount and the punch load and processing time during processing.

[0046] With this structure, the correction amount for the punch's infeed can be calculated more accurately.

[0047] The stamping apparatus of the fifth embodiment of the present invention may also include a first gap sensor for detecting when the punch is at the bottom dead center.

[0048] With this structure, it is possible to detect whether there is any misalignment between the upper die (including the punch) and the lower die (including the die) in the stamping forming apparatus.

[0049] The stamping forming apparatus of the sixth embodiment of the present invention may also include a second gap sensor for detecting the contact between the blank holder member and the die.

[0050] This structure allows for the detection of whether the relative position of the pressure member to the punching die is appropriate.

[0051] In the stamping forming apparatus of the seventh embodiment of the present invention, the die may include a plurality of die parts, and the die load sensor may be disposed on the plurality of die parts respectively.

[0052] With this structure, even when machining complex shapes, the gap correction amount can be accurately calculated, resulting in more stable machining.

[0053] The following description, based on the accompanying drawings, illustrates the implementation method.

[0054] (Implementation Method 1)

[0055] [Overall Structure]

[0056] Figure 1 This is a schematic diagram showing the stamping forming apparatus 100 of Embodiment 1. Figure 2 It is shown Figure 1 A schematic diagram of the upper dead center state of the punch 1 of the stamping forming device 100. Figure 3 It is shown Figure 1 A schematic diagram of the lower dead center state of the punch 1 of the stamping forming device 100. Figure 4 It is Figure 3 The image is obtained by magnifying the region R1. Figure 5 yes Figure 1 A top view of the die 2 and die plate 4 of the stamping forming apparatus 100. Figures 2-5 In the text, some constituent elements have been omitted.

[0057] like Figure 1 As shown, the stamping forming apparatus 100 includes a punch 1, a die 2, a blank holder 3, a die plate 4, a die load sensor 14, a control unit 30, a first drive unit 18, and a second drive unit 11, and is an apparatus for stamping workpieces such as metal sheets. In this embodiment, the stamping forming apparatus 100 is used for bending and deep drawing. In this embodiment, the stamping forming apparatus 100 also includes a punch load sensor 13, a first clearance sensor 15, and a second clearance sensor 16.

[0058] In the stamping forming apparatus 100, the gap between the die 2 and the blank holder 3 is corrected based on the loads applied to the die 2 and the punch 1 detected by the die load sensor 14 and the punch load sensor 13. By correcting the gap based on the load applied during processing, stable processing can be performed.

[0059] Punch 1 is a tool used to press against workpiece 5 for processing, and is mounted on sliding member 7.

[0060] like Figure 2 As shown, the die 2 has a hollow portion for inserting the punch 1, and has an inclined surface 2a that slopes from the upper surface 2b toward the hollow portion, and is mounted on the retainer 8. An ejector 6 is disposed in the hollow portion of the die 2 to push the processed workpiece 5 away from the die 2. The ejector 6 is driven by a cylinder 17.

[0061] like Figure 5 As shown, the die 2 includes four die parts 2c to 2f. Die part 2c and die part 2d have symmetrical shapes, and die part 2e and die part 2f have symmetrical shapes. In this embodiment, die part 2c and die part 2d are arranged facing each other in the Y direction, and die part 2e and die part 2f are arranged facing each other in the X direction.

[0062] The die 2 is composed of multiple die parts 2c to 2f. By adjusting the position of each die part 2c to 2f, the influence that may be caused by machining accuracy, surface roughness or wear of the punch 1 can be reduced, thus enabling stable machining.

[0063] The blank holder 3 is mounted on the sliding member 7 together with the punch 1, and presses the workpiece 5 against the inclined surface 2a of the die 2 during stamping. The blank holder 3 has a pressing surface 3a opposite to the inclined surface 2a of the die 2 (see reference). Figure 2 ).

[0064] The punching die 4 is a component that holds the punching die 2.

[0065] The sliding member 7 is connected to the servo motor 11 via the ball screw 12. By rotating the ball screw 12 using the servo motor 11, the sliding member 7 is driven at a predetermined speed along the stamping direction (Z direction). The sliding member 7 is guided by the shaft 10 to move up and down relative to the retainer 8 in the Z direction. By driving the sliding member 7 up and down relative to the retainer 8, the punch 1 can move toward the die 2 to perform bending and deep drawing on the workpiece 5 placed on the die 2. It should be noted that the servo motor 11 corresponds to the second drive unit in this embodiment.

[0066] Punch 1, die 2, blank holder 3, die plate 4, ejector 6, sliding member 7, retainer 8, and shaft 10 are assembled into the main body 9 of the forming device.

[0067] The die 2 moves along the stamping direction (Z direction) via the actuator 18 based on the clearance correction amount described later. It should be noted that the actuator 18 corresponds to the first drive unit in this embodiment.

[0068] The die load sensor 14 is a sensor that detects the load applied to the die 2 during processing. The die load sensor is a triaxial load sensor that detects the load applied to the die 2 as load components in three directions. In this embodiment, the die load sensor 14 detects the load applied to the die 2 as load components in the stamping direction (Z direction), a first direction perpendicular to the Z direction (X direction), and a second direction perpendicular to both the stamping direction and the first direction (Y direction).

[0069] In this embodiment, such as Figure 5 As shown, the die load sensor 14 includes four die load sensors 14c to 14f, one of each on each die part 2c to 2f. Die load sensors 14c and 14d are symmetrically arranged facing each other in the Y direction. Die load sensors 14e and 14f are symmetrically arranged facing each other in the X direction.

[0070] The punch load sensor 13 is a sensor that detects the load applied to the punch 1 during processing. The punch load sensor 13 measures the load Pz applied to the punch 1 in the punching direction (refer to...). Figure 3 A single-axis load sensor used for testing.

[0071] The control unit 30 calculates the vertical resistance of the die 2 based on the load detected by the die load sensor 14, and calculates the clearance correction amount between the die 2 and the blank holder 3 based on the vertical resistance of the die 2. Details of the control unit 30 will be described later.

[0072] The first clearance sensor 15 detects when the punch 1 is at its bottom dead center, i.e., at the lowest position it can reach. The first clearance sensor 15 is installed, for example, at any position on the lower die of the stamping apparatus 100, which includes the die 2, die plate 4, ejector 6, and retainer 8. It detects the punch 1 being at its bottom dead center by detecting the contact between the upper and lower dies, including the punch 1, the blank holder 3, and the slider 7. For example, by placing the first clearance sensors 15 at the four corners of the lower die, it is possible to detect whether the upper and lower dies are parallel.

[0073] The second gap sensor 16 is disposed at the four corners of the punching template 4 and detects the contact between the pressing member 3 and the punching template 4. In this embodiment, as... Figure 5 As shown, second gap sensors 16a to 16d are arranged at the four corners of the punching die 4. Based on the difference in the timing of contact between the pressing member 3 and the punching die 4 among the various second gap sensors 16a to 16d arranged at the four corners of the punching die 4, it is possible to detect whether the pressing member 3 and the punching die 4 are parallel.

[0074] The control unit 30 includes a second drive control unit 19, a first drive control unit 20, a sensor controller 21, an arithmetic unit 22, and a decision unit 23. The control unit 30 is composed of digital circuits such as microcomputers, CPUs, MPUs, GPUs, DSPs, FPGAs, and ASICs.

[0075] The second drive control unit 19 drives the servo motor 11 to rotate the ball screw 12, thereby causing the slider 7 to move up and down in the stamping direction (Z direction) at a predetermined speed.

[0076] The first drive control unit 20 drives the actuator 18 to move the die 2 along the stamping direction (Z direction) based on the clearance correction amount described later.

[0077] The sensor controller 21 is electrically connected to the die load sensor 14, the punch load sensor 13, the first gap sensor 15, and the second gap sensor 16, and outputs the detection values ​​of each sensor to the calculation unit 22 or the determination unit 23.

[0078] The calculation unit 22 calculates the vertical resistance and the impulse difference based on the detection values ​​from the die load sensor 14 or the punch load sensor 13. Details are described later.

[0079] The determination unit 23 determines whether to perform gap correction based on the calculation result of the calculation unit 22.

[0080] In the stamping forming apparatus 100, such as Figure 2 As shown, when the punch 1 is at its top dead center, the workpiece 5 is placed on the upper surface 2b of the die 2. The top dead center of the punch 1 refers to the highest position that the punch 1 can reach. With the workpiece 5 placed on the upper surface 2b of the die 2, the punch 1 is lowered in the stamping direction to begin processing.

[0081] As the punch 1 descends, the pressure member 3 mounted on the slider 7 also descends. As a result, as... Figure 3 As shown, the workpiece 5 is clamped and pressed by the pressing surface 3a of the pressing member 3 and the inclined surface 2a of the die 2, and the forming process is performed by the punch 1. Here, as Figure 4As shown, the inclined surface 2a of the die 2 is formed to be inclined at an angle θ1 relative to the upper surface 2b. In addition, the pressing surface 3a of the pressing member 3 is formed to be opposite to the inclined surface 2a of the die 2, that is, inclined at an angle θ1 relative to the upper surface 2b of the die 2.

[0082] As the punch 1 descends, its front end contacts the workpiece 5, shaping it. When the blank holder 3 contacts the die plate 4 (refer to...), Figure 3 ), punch 1 becomes the bottom dead center. At this time, as Figure 4 As shown, a predetermined gap CL is provided between the pressing member 3 and the die 2, and in this embodiment, between the pressing surface 3a of the pressing member 3 and the inclined surface 2a of the die 2.

[0083] In this embodiment, the position of the stamping direction of the die 2 or the amount of punch insertion of the punch 1 is adjusted based on the load detected by the die load sensor 14 and the punch load sensor 13 so that the gap CL becomes an appropriate value.

[0084] The die load sensor 14 detects the load applied to the die 2 from the start of the descent of the punch 1 until it reaches the bottom dead center. Specifically, the load applied to the die 2 is as follows: Figure 4 As shown, the load components are detected in three directions: the load Fz in the stamping direction (Z direction), the load Fx in the first direction (X direction), and the load Fy in the second direction (Y direction). The load Fz in the stamping direction is the load component acting along the stamping direction of the die 2. The loads Fx in the first direction and Fy in the second direction are load components in directions orthogonal to the stamping direction. It should be noted that the load Fy in the second direction is omitted from the illustration. The load Fy is a very small value compared to the loads Fx and Fz, so the effect of the load Fy on the loads Fx and Fz can be ignored. In this embodiment, the die load sensor 14 includes four die load sensors 14c to 14f respectively disposed on the die parts 2c to 2f. Therefore, the four die load sensors 14c to 14f detect the loads Fx, Fy, Fz in three directions and the vertical resistance N for each die part 2c to 2f.

[0085] The punch load sensor 13 detects the load applied to the punch 1 in the punching direction.

[0086] Reference Figure 6 The method for correcting the gap between the pressing surface 3a of the pressing member 3 and the inclined surface 2a of the punch 2 based on the load detected by the load sensors 13 and 14 will be described. Figure 6 Yes Figure 1 A flowchart illustrating the gap correction process of the stamping forming apparatus 100.

[0087] The gap CL between the pressing surface 3a of the blank holder 3 and the inclined surface 2a of the die 2 is pre-adjusted to an appropriate value, and forming begins (step S1). Next, the load applied to the die 2 is detected using the die load sensor 14 (step S2). The load F (Fx, Fy, Fz) detected by the die load sensor 14 is output to the arithmetic unit 22 via the sensor controller 21. Simultaneously with the load detection by the die load sensor 14, the load applied to the punch 1 is detected using the punch load sensor 13 (step S3). The load Pz detected by the punch load sensor 13 (refer to...) Figure 3 The signal is output to the calculation unit 22 via the sensor controller 21. When the forming is completed (step S4), the vertical resistance N of the die 2 is calculated by the calculation unit 22 (step S5).

[0088] The vertical resistance N of the die 2 is calculated using equation (1) based on the load F(Fx, Fy, Fz) of the die 2. In equation (1), θ1 is the angle of inclination of the inclined plane 2a relative to the upper surface 2b of the die 2 (refer to...). Figure 4 ).

[0089]

Mathematical Formula 1

[0090] N=Fx×sinθ1+Fz×cosθ1 (1)

[0091] After calculating the vertical resistance N, the impulse difference of the vertical resistance N for the die 2 is calculated using the calculation unit 22 (step S6).

[0092] Figure 7 This is a graph showing the relationship between the vertical resistance N of die 2 and the processing time t from the start of forming. (Example) Figure 7 As shown, the magnitude of the vertical resistance N of the die 2 calculated by the calculation unit 22 is obtained as waveform data representing the relationship with the processing time from the start of forming.

[0093] When the gap CL is of an appropriate value (in the case of the reference gap), the waveform data of the vertical resistance N becomes... Figure 7 The waveform is represented by a solid line. When the gap CL is larger than the reference gap, the waveform data of the vertical resistance N becomes... Figure 7 The waveform is represented by a single-dotted line. When the gap CL is smaller than the reference gap, the waveform data of the vertical resistance N becomes... Figure 7 The waveform is represented by the dashed line.

[0094] like Figure 7As shown, when the gap CL during forming is larger than the reference gap, the vertical resistance N of the die 2 is smaller than that of the reference gap throughout the forming time. Conversely, when the gap CL is smaller than the reference gap, the vertical resistance N of the die 2 is larger than that of the reference gap throughout the forming time.

[0095] The impulse of the vertical resistance N is the value obtained by multiplying the vertical resistance N by time, and is calculated by... Figure 7 The impulse difference of the die 2 is calculated based on the area of ​​the waveform data. The impulse difference refers to the difference between the impulse under the reference clearance condition and the impulse based on the vertical resistance N calculated in step S5. In this embodiment, the difference between the impulse based on the calculated vertical resistance N and the impulse under the reference clearance condition is calculated, and the size of the clearance CL is determined based on the value of the difference.

[0096] For example, the difference in impulse when the gap CL is larger than the reference gap is calculated by... Figure 7 The area of ​​region 70 is calculated. Additionally, the difference in impulse when the gap CL is smaller than the reference gap is calculated by... Figure 7 The area of ​​region 71 is calculated.

[0097] Based on the impulse difference of the vertical resistance N of the die 2, the determination unit 23 determines whether to perform clearance correction (step S7). For example, an upper limit and a lower limit of the impulse difference are preset, and if the value of the impulse difference exceeds the upper limit or is lower than the lower limit, it can be determined that clearance correction should be performed.

[0098] For example, if the impulse difference exceeds ±10% of the impulse when the reference gap is in the case of a reference gap, that is, the difference in waveform area between the two cases exceeds ±10%, then a gap correction is determined to be performed (Yes in step S7). In other words, if the impulse difference exceeds ±10% of the impulse when the reference gap is in the case of a reference gap, a gap correction is determined to be performed. If the impulse difference is within ±10% of the impulse when the reference gap is in the case of a reference gap, then the impulse difference is determined to be within the reference range, and no gap correction is performed (No in step S7).

[0099] If it is determined that gap correction is required (in step S7), the correction amount is calculated using the calculation unit 28 (in step S8). The correction amount is a value that indicates how much the size of the gap CL will be increased or decreased.

[0100] Figure 8 This is a graph showing the relationship between vertical resistance N and processing time t when the impulse difference is within ±20%. Figure 9 This is a graph showing the relationship between the impulse difference and the correction amount for the clearance CL. Figure 8In the diagram, region 72 represents the case where the impulse difference is -20%, and region 73 represents the case where the impulse difference is +20%. Figure 9 The chart was obtained by experimentally determining and plotting the correction amount for the clearance CL when the impulse difference is greater than -20% and less than +20%. Figure 9 In the figure, the horizontal axis represents the impulse difference (%), and the vertical axis represents the clearance correction amount (μm).

[0101] according to Figure 8 as well as Figure 9 The chart, for example, shows that the clearance is larger than the reference when the impulse difference is -20%, and the clearance correction is -10μm. That is, it shows that the correction is made by reducing the size of the clearance CL by 10μm. That is, it shows that the die 2 is moved upward (in the -Z direction). When the impulse difference is +20%, the clearance is smaller than the reference, and the clearance correction is +10μm. In this case, it shows that the correction is made by increasing the size of the clearance CL by 10μm. That is, it shows that the die 2 is moved downward (in the +Z direction).

[0102] Correction based on experimental results, such as Figure 9 As shown in the chart, if the correction amount is set as ΔCL and the impulse difference is set as D1, then equation (2) holds true.

[0103]

Mathematical Formula 2

[0104] ΔCL=a×D1 (2)

[0105] Here, the coefficient 'a' varies depending on factors such as the wear condition of the punch 1, and is therefore obtained, for example, at intervals of several impacts. Figure 9 The experimental results are presented in a chart-like format, and by changing the coefficient a, the accurate correction amount ΔCL can be calculated.

[0106] Next, the movement amount of the die 2 is calculated using the calculation unit 22 (step S9). The movement amount of the die 2 refers to the movement amount of the die 2 along the stamping direction.

[0107] Here, if the amount of movement is set as ΔH and the size of the reference gap is set as CL1, then the relationship between the amount of movement ΔH and the reference gap CL1 is valid according to equation (3).

[0108]

Mathematical Expression 3

[0109]

[0110] When the movement amount ΔH is positive, it means that the die 2 moves in the -Z direction; when the movement amount ΔH is negative, it means that the die 2 moves in the +Z direction.

[0111] Next, based on the calculated movement amount ΔH, the actuator 18 is driven to move the die 2, thereby correcting the size of the gap CL (step S10), and proceeding to step S11.

[0112] Returning to step S7, if it is determined that no clearance correction will be performed based on the impulse difference of the die 2 (No in step S7), the impulse difference for the load Pz applied to the punch 1 is calculated by the calculation unit 22 (step S12).

[0113] Figure 10 This is a graph showing the relationship between the load Pz applied to punch 1 and the processing time t from the start of forming. (Example) Figure 10 As shown, the magnitude of the load Pz applied to the punch 1 calculated by the calculation unit 22 is obtained as waveform data representing the relationship with the processing time from the start of forming.

[0114] When the indentation of punch 1 is at an appropriate value (the reference indentation value), the waveform data of load Pz becomes... Figure 10 The waveform is represented by a solid line. When the indentation is larger than the reference indentation, the waveform data of the load Pz becomes... Figure 10 The waveform is represented by a single-dotted line. When the indentation is smaller than the reference indentation, the waveform data of the load Pz becomes... Figure 10 The waveform is represented by the dashed line. It should be noted that the amount of punch 1 pressed in indicates the position of punch 1 when it reaches the bottom dead center.

[0115] The impulse of load Pz is the value obtained by multiplying load Pz by time, and is calculated by... Figure 10 The impulse difference of punch 1 is calculated based on the area of ​​the waveform data. The impulse difference of punch 1 is the difference between the impulse under the reference indentation and the impulse of the load Pz applied to punch 1 detected in step S3. In this embodiment, the difference between the impulse of the detected load Pz and the impulse under the reference indentation is calculated, and the value of the difference is used to determine whether to correct the indentation of punch 1.

[0116] For example, the difference in impulse when the magnitude of the indentation is larger than the reference indentation is calculated by... Figure 10 The area of ​​region 120 is calculated. Additionally, the difference in impulse when the amount of pressure applied is smaller than the reference amount is calculated... Figure 10 The area of ​​region 121 is calculated.

[0117] Based on the impulse difference of the load Pz, the determination unit 23 determines whether to perform a correction of the pressing amount (step S13). For example, an upper limit and a lower limit of the impulse difference are preset, and if the value of the impulse difference exceeds the upper limit or is lower than the lower limit, it can be determined that a correction of the pressing amount should be performed.

[0118] For example, if the impulse difference exceeds ±10% of the impulse in the case of the reference push amount, it is determined that a push amount correction should be performed (Yes in step S13). That is, if the impulse difference exceeds ±10% of the reference push amount, it is determined that a push amount correction should be performed. If the impulse difference is within ±10% of the reference push amount, it is determined that the impulse difference is within the reference range, and no push amount correction should be performed (No in step S13).

[0119] If it is determined that a correction to the pressing amount is required (in step S13), the correction amount is calculated using the calculation unit 28 (in step S14). The correction amount is a value that indicates how much the position of the punch 1 when it is in the bottom dead center state is moved along the pressing direction (Z direction).

[0120] Figure 11 This is a graph showing the relationship between load Pz and processing time t when the impulse difference is within ±20%. Figure 12 This is a graph showing the relationship between the impulse difference and the correction amount of the injection. Figure 11 In the diagram, region 122 represents the case where the impulse difference is -20%, and region 123 represents the case where the impulse difference is +20%. Figure 12 The chart was obtained by experimentally determining and plotting the correction amount for the injection volume when the impulse difference is greater than -20% and less than +20%. Figure 12 In the figure, the horizontal axis represents the impulse difference (%), and the vertical axis represents the correction amount of the press-in (mm).

[0121] according to Figure 11 as well as Figure 12 For example, when the impulse difference is -20%, the feed amount is shown to be smaller than the reference, and the correction amount for the feed amount is +0.2mm. That is, it shows that the position of the punch 1 when it is at the bottom dead center is moved 0.2mm downward in the stamping direction (+Z direction). Conversely, when the impulse difference is +20%, the feed amount is shown to be larger than the reference, and the correction amount for the feed amount is -0.2mm. In this case, it shows that the position of the punch 1 when it is at the bottom dead center is moved 0.2mm upward in the stamping direction (-Z direction).

[0122] Correction based on experimental results, such as Figure 12 As shown in the chart, if the correction amount is set as ΔPR and the impulse difference is set as D2, then equation (4) holds true.

[0123]

Mathematical Expression 4

[0124] ΔPR=-b×D2 (4)

[0125] Here, the coefficient b varies depending on the wear condition of the punch 1, etc., and is therefore obtained, for example, at intervals of several impacts. Figure 12 The experimental results are presented in a chart-like format, and by changing the coefficient b, the accurate correction amount ΔPR can be calculated.

[0126] Next, based on the calculated correction amount ΔPR, the servo motor 11 is controlled to correct the pressing amount of the punch 1 (step S15).

[0127] The process ends after the die 2 is moved (step S10) or the punch 1 is corrected in the amount of pressing in (step S15).

[0128] [Effect]

[0129] According to the present invention, a stamping forming apparatus capable of correcting clearance and performing stable processing can be provided. Specifically, according to the above-described embodiment, the clearance correction amount between the blank holder member and the die is calculated based on the vertical resistance of the die, thus providing a stamping forming apparatus capable of maintaining appropriate clearance and performing stable processing.

[0130] It should be noted that in the above embodiment, an example is described in which the stamping forming apparatus 100 is equipped with a punch load sensor 13 and the pressing amount of the punch 1 is corrected based on the load Pz applied to the punch 1, but the punch load sensor 13 is not a necessary structure.

[0131] Furthermore, in the above embodiment, an example of the die 2 being composed of four die parts 2c to 2f was described, but it is not limited to this. The die 2 may also be composed of a single die part, or it may be composed of two or more die parts. In this case, the die load sensor 14 is preferably disposed on each die part.

[0132] Furthermore, in the above embodiments, an example was described in which the stamping forming apparatus 100 is equipped with a first gap sensor 15 and a second gap sensor 16, but the first gap sensor 15 and the second gap sensor 16 are not necessary structures.

[0133] Industrial applicability

[0134] The stamping forming apparatus of the present invention can be applied to bending or deep drawing of workpieces such as household appliance and medical equipment parts that are thin, hard and difficult to stretch.

Claims

1. A stamping forming apparatus for processing plate-shaped workpieces, wherein, The stamping forming apparatus includes: The punch moves along the stamping direction; A die having a hollow portion into which the punch is inserted and having an inclined surface that slopes toward the hollow portion; A punching die, which holds the punching die; A pressure member is disposed between the punch and the die and has a pressing surface facing the inclined surface of the die; A die load sensor detects the load generated on the inclined surface of the die as loads in three directions: the load in the stamping direction, the load in a first direction perpendicular to the stamping direction, and the load in a second direction perpendicular to both the stamping direction and the first direction. The control unit calculates the vertical resistance of the die based on the load in the stamping direction, the load in the first direction, and the load in the second direction detected by the die load sensor, and calculates the clearance correction amount between the die and the blank holder based on the vertical resistance of the die. A first drive unit moves the die along the stamping direction based on the clearance correction amount; as well as The second drive unit drives the punch along the stamping direction.

2. The stamping forming apparatus according to claim 1, wherein, The clearance correction amount is calculated based on the difference between the impulse calculated according to the vertical resistance and processing time of the die under appropriate clearance and the impulse calculated according to the vertical resistance and processing time of the die during processing.

3. The stamping forming apparatus according to claim 1 or 2, wherein, The stamping forming apparatus also includes a punch load sensor for detecting the load applied to the punch along the stamping direction. The control unit calculates the punch insertion correction amount based on the punch load detected by the punch load sensor. The second drive unit drives the punch based on the indentation correction amount of the punch.

4. The stamping forming apparatus according to claim 3, wherein, The punch press-in correction is calculated based on the difference between the punch load and processing time under appropriate press-in conditions and the punch load and processing time during processing.

5. The stamping forming apparatus according to any one of claims 1 to 4, wherein, The stamping forming apparatus also includes a first gap sensor for detecting when the punch is at the bottom dead center.

6. The stamping forming apparatus according to any one of claims 1 to 5, wherein, The stamping forming apparatus also includes a second gap sensor for detecting the contact between the pressing member and the stamping die.

7. The stamping forming apparatus according to any one of claims 1 to 6, wherein, The die is composed of multiple die parts. The die load sensors are respectively disposed on the plurality of die parts.

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