JP6008641B2 - Method for measuring flange flatness of secondary battery case - Google Patents

Description

  The present invention relates to a method for easily and accurately measuring the flatness of a flange portion of a pressed product such as a case of a Li ion secondary battery.

Conventionally, in order to measure the flatness of the flange part of a pressed product, the product is placed on a flat measuring table such as a surface plate, and the clearance at the flange end is directly contacted with a measuring instrument such as a height gauge or caliper. There is a method of calculating the distance from the surface plate by measuring the distance of the upper surface of the flange that has been lifted using a non-contact displacement meter such as a laser displacement meter.
As the latter, for example, in Patent Document 1, a laser beam is emitted toward a sample to be measured, and the laser beam is irradiated to the sample, and the semiconductor laser is affected by return light from the sample. There has been proposed a flatness measurement method including a step of acquiring a frequency characteristic of laser light emitted in a state and calculating a flatness of the sample based on the acquired frequency characteristic.

Japanese Patent Laid-Open No. 2006-300624

  However, the former measurement method includes many measurement errors and takes a long time for measurement. Therefore, practical application as a quality inspection operation when manufacturing a press-processed product such as a case of a Li ion secondary battery is not realistic.

By the way, in a case such as a Li ion secondary battery, generally, two press-processed products are pasted together in a middle form, and a member serving as a battery is sealed to produce a product. In some cases, a member that serves as a battery is sealed in a press-processed product and a flat metal foil placed thereon to produce a product.
At this time, it is necessary to heat and press the heat-sealing resin coated on the inner side of the flange and seal it without gaps, but if the flange flatness of the heat-sealed part is poor, sufficient adhesive strength Can not get. Accordingly, it is necessary to accurately measure the flange flatness of the heat-sealed portion under a condition where a constant load is applied.
In the latter non-contact measurement method as found in Patent Document 1, the measurement itself can be performed with high accuracy and in a short time. However, the flange portion of the press-worked product joined to another member with a load applied. The flatness cannot be measured.

For this reason, the method of measuring the distance of the upper surface of the flange that has been lifted simply using a non-contact displacement meter such as a laser displacement meter is the flange part of a press-worked product such as a Li-ion secondary battery case. However, it is not always sufficient as a flatness measurement method.
The present invention has been devised to solve such problems, and is a method for measuring the flatness of a flange portion of a press-processed product quickly and accurately in a state where a load necessary for heat fusion is applied. The purpose is to provide.

In order to achieve the object of the method for measuring the flatness of the flange portion of the secondary battery case of the present invention, the slit hole and the flange portion of the secondary battery case on the stage with high flatness provided with the slit hole, There after placing the secondary battery case heat sealing resin is coated on the inside so as to face, in a situation in which by adding a constant load to the flange portion of the secondary battery the secondary battery the use case from the back side of the mount to the stage, the distance from the stage surface through the slit hole to the flange portion of the case for a secondary battery by measuring the non-contact displacement sensor, the flange portion of the case for a secondary battery It is characterized by measuring flatness.
The flatness can be determined by the difference between the maximum value and the minimum value of the distance of the case flange portion for the secondary battery from the stage surface.

  ADVANTAGE OF THE INVENTION According to this invention, the flatness of the flange part of the press work product used as cases, such as a Li ion secondary battery, can be known simply and accurately. In cases such as Li-ion secondary batteries, a member that acts as a battery is housed in the press-processed product, and the heat-sealing resin coated on the inside of the flange portion of the press-processed product is heated and pressurized to ensure no gaps. It is sealed. Therefore, by applying the present invention, it is possible to accurately know the flatness of the pressed product flange portion in a pressurized state, and conversely, it is necessary for the heat fusion of the flange portion having a predetermined roughness. The load can be easily known, and a case such as a Li ion secondary battery having excellent sealing accuracy can be stably manufactured at a low cost.

The figure explaining the appearance shape of the press processing product used as a case for a secondary battery The figure explaining the schematic structure of the flatness measuring apparatus used with the method of the present invention The figure explaining the height in each part when adopting the method of the present invention and measuring flatness The figure explaining the outline shape of the press work product measured in the Example Wrinkle presser force: Measurement result of flange flatness when measured at 50kN Wrinkle presser force: Measurement result of flange flatness when measured at 100kN Wrinkle holding force: Measurement result of flange flatness when measured at 200kN Wrinkle presser force: Measurement result of flange flatness when measured at 300kN Wrinkle holding force: Measurement result of flange flatness when measured at 400kN

As described above, in the case of a Li-ion secondary battery or the like, for example, is it possible to seal two members that have the appearance of the shape shown in FIG. In addition, a member that serves as a battery is sealed in a press-processed product and a flat metal foil placed thereon to produce a product. And the heat-sealing resin coat | covered on the inner side part of the flange of the said press work product is heated and pressurized, and it seals without a gap | interval and commercializes. Therefore, if the flange flatness of the heat-sealed part is poor, sufficient adhesive strength cannot be obtained. In the press-work product as shown in FIG. 1, the outer surface is coated with a lubricating film.
By the way, since the sealing is heat-sealed by pressing a flange with the heat-sealing resin coated on the inner side and applying a constant load to the other party, It is necessary to accurately know the flatness under a condition where a constant load is applied, not the flatness in a free state without pressure.

  Therefore, in the present invention, the member to be measured is placed on a stage having a high flatness in which a slit hole is provided at a position where the measurement part of the member to be measured contacts, so that the slit hole and the measurement part of the member to be measured are opposed to each other. After mounting, under the condition that a constant load is applied to the measurement site of the member to be measured, laser light is directed to the measurement site of the member to be measured from the back side of the stage on which the member to be measured is placed through the slit hole. The flatness of the measurement target measurement site is measured by measuring the distance of the measurement target measurement site from the stage surface.

As shown in FIG. 2, the apparatus to be used is a stage with high flatness, and a stage having linear slit holes on at least one side thereof, or slit holes in linear form on two opposite sides in parallel to each other. A holding bar is disposed on the upper side of the laser irradiation site, using a stage provided on the stage, a laser head provided on the back side of the stage, and an actuator for moving the laser head. The slit hole does not necessarily have to be a straight line, and may be a curve according to the shape of the member to be measured placed on the stage and the position of the part to be measured. The number of slit holes is not particularly limited.
Actual flatness measurement of the measured part to be measured requires four measurements by rotating the member to be measured if there is only one slit hole on the stage. If it exists, the member to be measured is rotated 180 degrees and only two measurements are required.

  Since the measurement is performed under the condition that a constant load is applied to the measurement site of the member to be measured, it is preferable that the pressing bar has the same shape (the same area) as the pressing jig at the time of thermal fusion. Further, it is preferable that a weight is placed on the holding bar so that the load can be changed by exchanging the weight. At this time, a mounting screw is provided on the upper surface of the pressing bar, and a weight with a central through hole is placed on the pressing bar so that the through hole is inserted into the mounting screw through a urethane washer. Preferably, a nut is screwed into the mounting screw so that the weight is not twisted. At this time, if the weight is firmly fixed to the holding bar, twisting is caused. Therefore, it is preferable that the mounting screw is placed on the holding bar in a free state with an appropriate gap.

For the measurement data, as shown in FIG. 3, the flatness is defined as the difference between the minimum value and the maximum value. The reason why the minimum value is used is that, even if the heat-sealing resin is transparent and is in contact with the stage without any gap, the height is increased by the thickness of the resin.
In the above description, the distance from the stage surface is measured by laser light irradiation. However, the distance measurement is not limited to the laser type, and is not a contactless type such as an eddy current type, an optical type, or an ultrasonic type. Any type of displacement meter may be used.

A 0.1 mm-thick austenitic stainless steel foil having the component composition shown in Table 1 and the mechanical properties shown in Table 2, which is made of a metal foil with a lubricating film on the outer surface and a heat-sealing resin on the inner surface As shown in FIG. 4, a shallow drawn product having the shape shown in FIG. The unit of the size in FIG. 4 is mm.
The shallow drawing product was manufactured using a 2000 kN servo press and changing the wrinkle pressing force from 50 to 400 kN.

  The width of the slit hole provided in the stage of the measuring device was 2.5 mm, and a CCD laser displacement meter was used. The laser light of the displacement meter is a red semiconductor laser with a wavelength of 650 nm, and the spot diameter is about φ30 μm at a reference distance of 30 mm. The reflected laser light detection device detects the reflected light collected by the lens at a sampling period of 500 μs, a repetition accuracy of 0.1 μm, and ± 5 mm from the reference position. Further, a uniaxial actuator for moving the displacement meter has a parallelism of 0.025 mm.

The measurement results of the flange flatness on the long side (Stage 1) and the short side (Stage 2) of the shallow drawn product produced with each wrinkle pressing force are shown in FIGS. The weight of the weight placed on the holding bar is 5 kg. For measurement, Stage1 is provided with two slits so that the two long sides of the shallow drawn product can be measured at once, and two slits are provided so that two short sides can be measured at once. The measurement was performed using two flatness measuring machines of Stage 2.
Table 3 summarizes the measurement results of FIGS. In Table 3, when the flatness exceeds 0.050 mm, NG (×) determination is made.
As can be seen from Table 3, the flatness within 0.050 mm is not satisfied when the wrinkle pressing force is 100 kN or less. In other words, if the flatness is specified within 0.050 nm in the heat sealing process, it is necessary to select and process the wrinkle pressing force condition exceeding 100 kN.

Claims (2)

A secondary battery case that is covered with a heat-sealing resin on the inside so that the slit hole and the flange portion of the secondary battery case face each other is placed on a stage with high flatness provided with slit holes. After that, under a situation where a constant load is applied to the flange portion of the secondary battery case , from the back side of the stage on which the secondary battery case is placed, the secondary battery case is removed from the stage surface through the slit hole . by measuring the distance to the flange portion by a non-contact type displacement meter, a flange portion flatness measuring method of the case for a secondary battery, characterized by measuring the flatness of the flange portion of the case for a secondary battery. The method for measuring flatness of a flange portion of a secondary battery case according to claim 1, wherein the flatness is determined by a difference between a maximum value and a minimum value of a distance of the case flange portion of the secondary battery from the stage surface.