JP2009022986A - Blanking apparatus provided with fracture measurement function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the yield of a formed product in which working is applied to a blanked fracture. <P>SOLUTION: The blanking apparatus comprises: a blanking punch; a die; and a stroke amount measuring means for the blanking punch. In the side face of the blanking punch, a displacement gauge measuring the distance with a workpiece is buried. The blanking device further comprises a calculation means calculating one or more kinds selected from the sagging ratio, sheared face ratio and fracture ratio on the basis of the measured value by the displacement gauge. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a stamping process of a metal plate made of iron, aluminum, titanium, magnesium and alloys thereof used in automobiles, home appliances, building structures, ships, bridges, construction machines, various plants, penstocks, etc. It relates to molding.

  A metal plate 1 such as an automobile, home appliance, or building structure is often punched by a punch 2 and a punch die 3 as shown in FIG. FIG. 1A shows a side cross-sectional view (vertical cross-sectional view passing through the hole center of the die 3 having a round hole) when punching into a closed cross-section such as a round hole. FIG.1 (b) shows the side view at the time of cut | disconnecting a strip | belt board into two with a shear | punching and punching into an open cross section, for example.

  As shown in FIG. 2, the punched fracture surface is formed when the workpiece 1 is entirely pushed by the punch 2 4, and the workpiece 1 is drawn into the clearance between the punch 2 and the die 3 locally. Constructed by a stretched shear surface 5, a fracture surface 21 formed by breaking the workpiece 1 drawn into the clearance between the punch 2 and the die 3, and a flash 6 generated on the back surface of the workpiece 1. Is done.

  As shown in FIG. 3, there are cases where the shear surface has two layers (FIG. 3 (a)) and three layers (FIG. 3 (b)). Called. In this case, the secondary shear surface 7 and the tertiary shear surface 8 are defined as a shear surface.

In the present invention, the length in the plate thickness direction of the droop 4 shown in FIG. 2 is L1 [mm], the length in the plate thickness direction of the shear surface 5 is L2 [mm], and the length in the plate thickness direction of the fracture surface 21 is set. When L3 [mm] and the plate thickness are L [mm],
Drool rate = L1 / L × 100 [%] (1)
Shear area ratio = L2 / L × 100 [%]
(2)
Fracture surface ratio = L3 / L × 100 [%] (3)
It is defined as

Similarly, if the lengths of the secondary shear surface 7 and the tertiary shear surface 8 in FIGS. 2 and 3 are L2s [mm] and L2t [mm], respectively, the shear surface ratio is (4 )
Shear area ratio (including secondary and tertiary shear planes) = (L2 + L2s + L2t) / L × 100 [%] (4)

  As described in Non-Patent Document 1, it is widely known that the characteristics of these punched fracture surfaces are affected by material characteristics, punching speed, punching load, clearance amount, tool conditions such as die wear, and the like. . Stretch flange processing is an example of a process in which cracking due to punched fracture surface properties becomes a problem, but it is known that stretch flange characteristics depend on the clearance amount of the punching tool as described in Non-Patent Document 2. In other words, the above-described features of the punched fracture surface are greatly affected.

In a factory where mass production of molded products including punching and subsequent molding is performed, such as stretch flange processing, the clearance amount of the punching tool and blade wear management are often performed in order to prevent yield deterioration due to molding defects. . In order to manage the clearance amount, it is necessary to measure the clearance amount. In such a measurement technique, the clearance amount is measured by measuring the position of the punch punch core with a non-contact displacement meter described in Patent Document 1. And a test layer made of an easily deformable material is attached to the side surface of the punch described in Patent Document 2, and the punch is fitted to the die, and then the clearance amount is measured from the state of the test layer left on the side surface of the punch A method to do this has been proposed. For blade wear management, tool change is often performed after the number of punches determined empirically. In addition to this, tool wear is determined by estimating blade wear from the measured acoustic emission of the punch tool. Non-Patent Document 3 and Patent Document 3 describe the method to do this.
JP 2000-301398 A JP-A-7-151536 JP 2005-219173 A The 96th Plastic Processing Course "Fundamentals and Applications of Plate Forming" Plasticity and processing, 46 (2005), pp.625 Transactions of the Japan Society of Mechanical Engineers C Vol.71 No.712 Page.3614-3621 (2005.12.25)

  The above proposed technology has several problems when applied to a mass production factory. The factors that affect the formability of the punched fracture surface are the work hardening of the punched fracture surface of the workpiece and the degree of stress concentration due to the fracture surface shape, and the processing conditions are an indirect factor. In order to increase the yield, it is not sufficient to measure only the clearance amount and the wear of the punching blade. For example, environmental factors such as variations in material properties and temperature may also affect. The conventional proposed technique described above is a method for monitoring the state of the mold, not the method for monitoring the state of the workpiece. Moreover, when it is going to estimate the state of a workpiece from a metal mold | die or an environmental factor, if an apparatus which measures all these factors is provided, it will take a great effort and cost.

  An object of the present invention is to provide a punching device that can improve the yield of a molded product in which a punched fracture surface is processed after the punching process regardless of variations in material characteristics and environmental factors such as air temperature. And

In order to solve the above problems, the gist of the present invention is as follows.
(1) It has a punching punch, a die, and a stroke amount measuring means for the punching punch, a displacement meter for measuring the distance from the workpiece is embedded in the side surface of the punching punch, and the stroke amount measurement And a calculating means for calculating at least one of a dripping rate, a shearing surface rate, and a fracture surface ratio of the punched fracture surface of the workpiece based on the measured value of the means and the measured value of the displacement meter, A punching device with a fracture surface measurement function.
(2) The punching device having a fracture surface measuring function according to (1), wherein the displacement meter is a non-contact type laser displacement meter or a non-contact type optical fiber displacement meter.
(3) The displacement meter is a pin that measures the displacement of the workpiece while being in contact with the workpiece by the elastic force of the elastic means embedded in the side surface of the punching punch (1) A punching device having the described fracture surface measuring function.
(4) The arithmetic means has a function of calculating a shear surface ratio by setting a punch stroke amount when a variation of a measured value of the displacement meter is equal to or less than a predetermined value as a shear surface length ( A punching device having the fracture surface measuring function according to any one of 1) to (3).
(5) The difference between the punch stroke amount at the time when the calculation means starts the contact between the bottom surface of the punching punch and the surface of the workpiece, and the punch stroke amount at the time when the variation of the displacement meter becomes a predetermined value or less. From any one of (1) to (3), it has a function of calculating a drooping rate by taking a length obtained by subtracting a distance from the bottom surface of the punch at the installation position of the displacement meter as a drooping length. A punching device equipped with the fracture surface measuring function described in 1.

  According to the present invention, it is possible to determine at the time of punching whether or not the occurrence of stretch flange cracks that occur during molding such as press molding after punching without stopping the mass production line. The yield of goods can be improved.

  In the present invention, on the mass production line from the punching of metal material to the forming process, before the stretch flange deformation at the time of forming process, the punched fracture surface shear rate, shear surface ratio, fracture surface ratio at the stage after punching It is characterized by measuring.

  In the present invention, stretch flange deformation refers to deformation by applying tensile stress to a punched fracture surface by molding. For example, when the steel plate shown in FIG. 4A is formed as shown in FIG. Further, in the present invention, defective molding refers to stretch flange cracks associated with molding.

  From the conventional knowledge that the characteristics of the punched fracture surface influences the formability of the punched fracture surface, the present inventors measure any of the dripping rate, shear surface ratio, and fracture surface ratio of the punched fracture surface during the punching. Therefore, it was found that the defect determination (prediction) of the member after the forming process can be performed with higher accuracy before the blank forming, and the effect of improving the yield of the mass production line can be obtained.

From this point of view, we initially tried to observe the punched fracture surface on the mass production line, but with a thickness of 1 to 3 mm, the shear surface, fracture surface, etc. with an accuracy of 1 mm or less. It was necessary to determine the difference in the shape of the fracture surface, and it was concluded that it was impossible to visually determine the defect of the punched fracture surface.
The measurement of the drooling rate, shear surface rate, and fracture surface ratio at the experimental level is mainly performed by observing the fracture surface with a microscope on the test piece cut out only around the punched fracture surface. It is impossible to make such an observation on the mass production line from the viewpoint of time.

  Therefore, the present inventors made trial and error and embedded a displacement meter 9 on the side surface of the punch 2 that is in contact with the workpiece 1 during punching as shown in FIG. 5 in a punching device that can measure the stroke amount of the punch. Invented a punching device that can determine the occurrence of stretch flange cracks caused by the molding process in the subsequent process by calculating the dripping rate, shear surface rate, and fracture surface rate of the punched fracture surface based on the value and the punch stroke amount (Invention according to (1)).

  That is, if the stroke amount from the initial state is X (mm) and the distance to the workpiece is Y (mm), the punched fracture surface shown in FIGS. 2 and 3 is represented by two-dimensional coordinates (X, Y). The shape can be grasped, and on the basis of these measured values, the dripping rate, the shearing surface rate, and the fracture surface rate of the punched fracture surface are calculated based on the equations (1) to (4).

  When the droop rate is larger than a predetermined value, when the shearing surface ratio is larger than a predetermined value, or when the fracture surface ratio is smaller than a predetermined value, it is determined that there is a high possibility that stretch flange cracks will occur due to the subsequent forming process.

  This is because stretch flange cracks are more likely to occur as the dripping rate and shearing rate of the punched fracture surface increase. In addition, if the fracture surface ratio is smaller than a predetermined value, either the shearing surface ratio or the drooping rate inevitably increases.

  As for the installation position of the displacement meter 9, it is preferable that the punched end face considered to have the highest risk of stretch flange cracking can be measured, such as the semicircular part of the stretch flange part 21 shown in FIG. .

  Further, the height of the measurement center of the displacement meter 9 from the bottom surface of the punch 2 is the expected droop length L1, the shear surface length (L2 + L2s + L2t), and the distance Ld of the punch bottom dead center from the die bottom surface (see FIG. 5). Or less than the sum of This is because the blade in the vicinity of the displacement meter 9 must be high enough to measure the punched end face history up to the shear plane without lacking rigidity and lacking.

  When the displacement meter 9 embedded in the side surface of the punch 2 is a non-contact type, a laser displacement meter, an optical fiber displacement meter, or the like can be considered (the invention according to (2) above).

  Since the punching speed of punching is usually as high as 30 to 200 [mm] per second, these displacement meters must have high resolution and high response speed. Depending on the plate thickness of the workpiece 1, the resolution of the laser displacement meter or the optical fiber displacement meter can be about 10 to 50 [μm], and the response frequency can be 1 [kHz] or more, so any one of these is desirable. As an installation method, for example, as shown in FIG. 6A, a hole is formed in the side surface of the punch 2 to embed the screw type sensor probe 10, or the sensor head 11 itself is incorporated into the punch and fixed with the screw 12. Is mentioned.

  As the displacement meter 9 installed on the side surface of the punch 2, as shown in FIG. 7, a pin 15 supported by an elastic body 14 such as a spring is embedded in the side surface of the punching punch 2, and the workpiece is in contact with the workpiece. May be measured (the invention according to (3) above). In this case, the elastic force of the elastic body 14 is measured by the load cell 13 and converted into a displacement. The shape of the pin 15 in contact with the workpiece is preferably such that the pin 15 is tapered and rounded so as not to be caught on the workpiece 1 as shown in FIG. In addition, the contact displacement meter preferably has a high resolution and a high response frequency in the same manner as the non-contact displacement meter.

  In this method, the displacement rate of the punched fracture surface, the shear surface rate, and the fracture surface area ratio are calculated by the displacement meter 9 installed on the side surface of the punch 2. When a shear surface characterized by a flat shape is obtained, the punch 2 The punch stroke amount when the fluctuation of the output of the lateral displacement meter 9 is a predetermined value (about resolution) or less may be calculated by the formula (2) or (4) as the length of the shear plane (the above ( 4), if the stroke amount at which the bottom surface of the punch 2 starts to contact the surface of the workpiece 1 is measured in advance, the variation in the stroke amount and the measured value of the displacement meter 9 is a predetermined value. The length obtained by subtracting the height from the bottom surface of the punch 2 at the installation position of the displacement meter 9 from the difference in the stroke amount at the start time as follows can be calculated by the equation (1) ((5 ).

  Further, the difference between the punch stroke amount at the end when the fluctuation of the output of the punch 2 side surface displacement meter 9 becomes a predetermined value (about resolution) or less and the punch stroke amount when the output of the displacement meter 9 changes discontinuously is obtained. In addition, the fracture surface ratio can also be calculated by equation (3).

  In order to confirm the effect of the present invention, an experiment using the apparatus shown in FIG. 9 was conducted. The apparatus shown in FIG. 9 is capable of measuring the punch stroke amount with a roller-type displacement meter 16 (stroke amount measuring means) provided in the punch holder 17, and inside the punch 2 as shown in FIG. 6 (b). The distance from the side surface (laser displacement meter 11) of the punch 2 to the punched fracture surface can be measured by the incorporated laser displacement meter 11. These displacement meters are connected to a personal computer 19 (calculation means), and when the measured values of the two displacement meters 11 and 16 are processed, the variation of the measured values of the laser displacement meter 11 is 0.04 mm or less. The punch stroke amount is calculated as the shear plane length. In addition, calibration is performed so that the output of the roller displacement meter 16 at the stroke amount when the bottom surface of the punch 2 and the surface of the workpiece 1 are in contact with each other is 0 [mm]. From the difference of the output [mm] of the roller-type displacement meter 16 from the time when the surface of the workpiece 1 starts to contact until the fluctuation of the measured value of the laser displacement meter 11 becomes 0.04 [mm] or less, the laser displacement meter The length obtained by subtracting the distance from the bottom surface of the punch at the installation position 11 is calculated as the amount of droop.

  With this apparatus, the plan view was punched in the punched cut shape shown in FIG. The laser displacement meter 11 measures the stretch flange crack risk part shown in FIG. The punching clearance was 2 patterns of 5% and 10% of the plate thickness. A high-tensile steel plate having a tensile strength of 590 MPa and a plate thickness of 1.2 [mm] was used as the workpiece. In an experiment in which stretch flange molding is performed so that the final shape is as shown in FIG. 11, this material is judged to have a high risk of cracking in the stretch flange molding process when the shear surface ratio is 30% or more. Is. In this example, a secondary shear surface and a tertiary shear surface were not generated.

  As for the droop length and the shear surface length, those measured by this apparatus and those derived from a cross-sectional photograph taken by cutting out the punched material are shown in FIG. 12 (the droop length (a) and the shear length when the clearance is 5%). (B)) and FIG. 13 (sag length (a) and shear length (b) when the clearance is 10%) (the values divided by the plate thickness are the respective ratios). The measurement results with this device are within 5% of the error derived from the cross-sectional photograph, indicating that the measurement was performed correctly.

  When the above-mentioned stretch flange test was performed, a punched material with a clearance of 5% caused cracks in the stretch flange and did not occur with a punch of 10%. According to the measurement results of this device, the punched material with a clearance of 5% has a shear surface ratio exceeding 30% (= 1.2 × 0.3 = 0.36), and the shear surface ratio of the workpiece is 30% or more. This is consistent with the finding that there is a high risk of cracking in the stretch flange forming process. Therefore, it can be said that this apparatus can identify a member in which stretched flange cracking occurs and can improve the yield of a member whose punched fracture surface is processed.

  In order to confirm the effect of the present invention, an experiment using the apparatus shown in FIG. 14 was conducted. The apparatus shown in FIG. 14 can measure the punch stroke amount with a roller-type displacement meter 16 (stroke amount measuring means) provided in the punch holder 17, and can punch with a contact-type displacement meter 20 incorporated in the punch 2. The distance between the two side surfaces (contact displacement meter) and the punched fracture surface can be measured. The contact displacement meter 20 has a configuration as shown in FIG. A load cell 13 is embedded in the bottom surface of the hole formed in the side surface of the punch 2, and a pin 15 that is in contact with the load cell 13 and the punched fracture surface is connected by a coil spring 14. The amount of deflection of the spring 14 is obtained from the load value measured by the load cell 13 and converted into displacement. These displacement meters are connected to a personal computer 19 (calculation means), and when the measured values of the two displacement meters 16 and 20 are processed and the variation of the measured values of the contact displacement meter 20 is 0.04 mm or less. The punch stroke amount is calculated as the shear plane length. The bottom surface of the punch 2 is calibrated so that the output of the roller-type displacement meter 16 is 0 [mm] at the stroke amount when the bottom surface of the punch 2 and the surface of the workpiece 1 start to contact. From the difference in the output [mm] of the roller-type displacement meter 16 from the time when the surface of the workpiece 1 starts to contact and the fluctuation of the measured value of the contact-type displacement meter 20 becomes 0.04 [mm] or less, The length obtained by subtracting the distance from the bottom surface of the punch at the installation position of the laser displacement meter 20 is calculated as the amount of droop.

  With this apparatus, punching was performed with the same test piece shape and punching conditions as in Example 1. Figure 15 (sag length (a) and shear length in the case of 5% clearance) are measured with this apparatus and derived from a cross-sectional photograph taken by cutting a punched material. (B)) and FIG. 16 (sag length (a) and shear length (b) when clearance is 10%) (values divided by plate thickness are the respective ratios). The measurement results with this device are within 5% of the error derived from the cross-sectional photograph, indicating that the measurement was performed correctly.

  When the above-mentioned stretch flange test was performed, a punched material with a clearance of 5% caused cracks in the stretch flange and did not occur with a punch of 10%. As a result of measurement by this apparatus, the punched material with a clearance of 5% has a shear surface ratio exceeding 30% (= 1.2 × 0.3 = 0.36 mm), and the workpiece has a shear surface ratio of 30% or more. This is consistent with the finding that there is a high risk of cracking in the stretch flange forming process. Therefore, it can be said that this apparatus can identify a member in which stretched flange cracking occurs and can improve the yield of a member whose punched fracture surface is processed.

It is the figure which showed typically the cutting process by punching. (A) It is a sectional side view which shows the case of closed cross-section punching. (B) It is a side view which shows the case of an open section punching. It is a figure which shows typically the to-be-processed material end surface of the cutting process by punching. It is a figure which shows typically the punching fracture surface which has a secondary and a tertiary shear surface. (A) It is a schematic diagram of the cross section which has a secondary shear surface. (B) It is a schematic diagram of the cross section which has a tertiary shear surface. It is a figure which shows a stretch flange deformation | transformation typically. (A) The blank before a shaping | molding process is shown. (B) The member after forming is shown. It is a sectional side view which shows the example of an apparatus of this invention. It is a figure which shows typically the example of the incorporation to the punch of a non-contact-type displacement meter. (A) In the case of embedding a probe, o is indicated. (B) The case where the probe is embedded in the punch head is shown. It is a figure which shows typically the example of the incorporation to the punch of a contact-type displacement meter. (A) A pin with a taper angle is shown. (B) A rounded pin is shown. It is a figure which shows typically the example of a pin shape which is a structural example of a contact-type displacement meter, and a structural member. It is a figure which shows typically the apparatus used in Example 1. FIG. It is a figure which shows typically the shape of the punching part in Example 1,2. It is a figure which shows typically the workpiece shape after the stretch flange test in Example 1,2. In Example 1, it is a figure which shows the comparison of the measurement result of the fracture surface shape obtained from the fracture surface shape measurement result by this apparatus, and a cross-sectional photograph. (A) Shows the droop length (clearance = 5% of plate thickness). (B) Shows the shear plane length (clearance = 5% of plate thickness). In Example 1, it is a figure which shows the comparison of the measurement result of the fracture surface shape obtained from the fracture surface shape measurement result by this apparatus, and a cross-sectional photograph. (A) Shows the length of the droop (clearance = 10% of the plate thickness). (B) Shows the shear plane length (clearance = 10% of plate thickness). It is a figure which shows typically the apparatus used in Example 2. FIG. In Example 2, it is a figure which shows the comparison of the measurement result of the fracture surface shape obtained from the fracture surface shape measurement result by this apparatus, and a cross-sectional photograph. (A) Shows the droop length (clearance = 5% of plate thickness). (B) Shows the shear plane length (clearance = 5% of plate thickness). In Example 2, it is a figure which shows the comparison of the measurement result of the fracture surface shape obtained from the fracture surface shape measurement result by this apparatus, and a cross-sectional photograph. (A) Shows the length of the droop (clearance = 10% of the plate thickness). (B) Shows the shear plane length (clearance = 10% of plate thickness).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Workpiece 2 Punching punch 3 Punching die 4 Drooping at punching fracture surface 5 Shearing surface at punching fracture surface 6 Burr at punching fracture surface 7 Secondary shearing surface at punching fracture surface 8 Tertiary shearing surface at punching fracture surface 9 Punching punch Displacement meter 10 embedded in a side surface Non-contact displacement meter screw type probe 11 Non-contact displacement meter sensor head 12 Screw for fixing the non-contact type head 13 Load cell 14 Spring-like elastic body (in the embodiment, (Quoted as coil spring)
15 Pin 16 constituting contact displacement meter Roller displacement meter 17 Punch holder 18 Reverse plate holder 19 Personal computer 20 Contact displacement meter 21 Fracture surface 22 on punched fracture surface Stretch flange

Claims (5)

  It has a punching punch, a die, and a stroke amount measuring means for the punching punch, a displacement meter for measuring a distance from the workpiece is embedded in a side surface of the punching punch, and further measuring by the stroke amount measuring means And a calculation means for calculating one or more of a dripping rate, a shear surface rate, and a fracture surface ratio of a punched fracture surface of a workpiece based on a value and a measurement value of the displacement meter Punching device with measuring function.   2. The punching device having a fracture surface measuring function according to claim 1, wherein the displacement meter is a non-contact type laser displacement meter or a non-contact type optical fiber displacement meter.   2. The break according to claim 1, wherein the displacement meter is a pin that measures the displacement of the workpiece while being in contact with the workpiece by the elastic force of the elastic means embedded in the side surface of the punching punch. Punching device with surface measurement function.   The said calculating means has a function which calculates a shear surface rate by making the amount of punch strokes when the change of the measured value of the displacement meter is below a predetermined value into a shear surface length. A punching device having the fracture surface measuring function according to any one of 3 above.   From the difference between the punch stroke amount at the time when the bottom surface of the punching punch and the surface of the workpiece start to contact and the punch stroke amount at the start point when the displacement of the displacement meter becomes a predetermined value or less, The fracture surface according to any one of claims 1 to 3, wherein the fracture surface has a function of calculating a drooping rate, with a length obtained by subtracting a distance from the bottom surface of the punch at the installation position of the displacement meter as a drooping length. Punching device with measuring function.

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