Welding quality inspection device

1. An apparatus for inspecting a welding state in a welded portion for an electronic or mechanical coupling in a lithium secondary battery, comprising:

a measuring unit configured to obtain data for deriving a resistance value of the welded portion by allowing a resistance measuring probe to contact the welded portion; and

a controller configured to communicate with the measuring unit, determine the resistance value of the welded portion by receiving the data obtained from the measuring unit, and determine whether a weak welding was performed by comparing the determined resistance value with a threshold resistance value,

wherein the measuring unit comprises:

a pair of resistance measuring probes configured to obtain data for determining the resistance value by contacting one end and the other end of the welded portion;

a flat cradle on which a subject is mounted;

an upper plate on an upper portion having a predetermined separation distance from the flat cradle and includes a plurality of through holes into which the resistance measuring probe is insertable;

a lower plate on a lower portion having a predetermined separation distance from the flat cradle and includes a plurality of through holes into which the resistance measuring probe is insertable; and

a coupling unit configured to allow the flat cradle, the upper plate and the lower plate to be coupled to each other, and including a coupling bar and a coupling screw,

wherein each of the pair of resistance measuring probes comprises a current probe and a voltage probe, and

wherein the resistance value of the welded portion is measured by a 4-wire measuring scheme,

wherein the flat cradle, the upper plate and the lower plate each has coupling holes at 4 edge portions, and

wherein the flat cradle, the upper plate and the lower plate are coupled as the coupling bar sequentially passes through coupling holes disposed on the upper plate, the flat cradle and the lower plate.

2. The apparatus of claim 1 , wherein the controller determines that a weak welding was performed if the determined resistance value exceeds the threshold resistance value.

3. The apparatus of claim 1 , wherein an upper guide member and a lower guide member for allowing the resistance measuring probe to be inserted into a correct position are coupled to the upper plate and the lower plate, respectively.

4. The apparatus of claim 3 , wherein the upper guide member and the lower guide member have through holes into which the resistance measuring probe is insertable, respectively,

wherein the through holes of the upper guide member and the through holes of the upper plate are located on a straight line to thereby allow the resistance measuring probe to pass the through holes to approach an upper surface of the welded portion, and

wherein the through holes of the lower guide member and the through holes of the lower plate are located on a straight line to thereby allow the resistance measuring probe to pass the through holes to approach a lower surface of the welded portion.

5. The apparatus of claim 1 , wherein the controller includes a threshold resistance value setting program for setting the threshold resistance value by processing data obtained for a sample group by a statistical scheme.

6. The apparatus of claim 5 , wherein resistance values determined from data obtained for the sample group correspond to a normal distribution curve.

7. The apparatus of claim 1 , further comprising a power source configured to apply power to the measuring unit,

wherein the power is a direct current (DC) power and is controlled by the controller.

8. An apparatus for inspecting a welding state in a welded portion for an electronic or mechanical coupling in a lithium secondary battery, comprising:

a measuring unit configured to obtain data for deriving a resistance value of the welded portion by allowing a resistance measuring probe to contact the welded portion; and

a controller configured to communicate with the measuring unit, determine the resistance value of the welded portion by receiving the data obtained from the measuring unit, and determine whether a weak welding was performed by comparing the determined resistance value with a threshold resistance value,

wherein the measuring unit comprises:

a pair of resistance measuring probes configured to obtain data for determining the resistance value by contacting one end and the other end of the welded portion;

a flat cradle on which a subject is mounted;

an upper plate on an upper portion having a predetermined separation distance from the flat cradle and includes a plurality of through holes into which the resistance measuring probe is insertable;

a lower plate on a lower portion having a predetermined separation distance from the flat cradle and includes a plurality of through holes into which the resistance measuring probe is insertable; and

a coupling unit configured to allow the flat cradle, the upper plate and the lower plate to be coupled to each other, and including a coupling bar and a coupling screw,

wherein each of the pair of resistance measuring probes comprises a current probe and a voltage probe, and

wherein the apparatus further comprises a compression spring for adjusting a separation distance between the flat cradle and the upper plate and a separation distance between the flat cradle and the lower plate,

wherein the resistance value of the welded portion is measured by a 4-wire measuring scheme,

wherein the coupling bar is configured to be insertable into a hollow portion of the compression spring.

9. The apparatus of claim 8 , wherein the controller determines that a weak welding was performed if the determined resistance value exceeds the threshold resistance value.

10. The apparatus of claim 8 , wherein an upper guide member and a lower guide member for allowing the resistance measuring probe to be inserted into a correct position are coupled to the upper plate and the lower plate, respectively.

11. The apparatus of claim 10 , wherein the upper guide member and the lower guide member have through holes into which the resistance measuring probe is insertable, respectively,

wherein the through holes of the upper guide member and the through holes of the upper plate are located on a straight line to thereby allow the resistance measuring probe to pass the through holes to approach an upper surface of the welded portion, and

wherein the through holes of the lower guide member and the through holes of the lower plate are located on a straight line to thereby allow the resistance measuring probe to pass the through holes to approach a lower surface of the welded portion.

12. The apparatus of claim 8 , wherein the controller includes a threshold resistance value setting program for setting the threshold resistance value by processing data obtained for a sample group by a statistical scheme.

13. The apparatus of claim 12 , wherein resistance values determined from data obtained for the sample group correspond to a normal distribution curve.

14. The apparatus of claim 8 , further comprising a power source configured to apply power to the measuring unit,

wherein the power is a direct current (DC) power and is controlled by the controller.

15. An apparatus for inspecting a welding state in a welded portion for an electronic or mechanical coupling in a lithium secondary battery, comprising:

a measuring unit configured to obtain data for deriving a resistance value of the welded portion by allowing a resistance measuring probe to contact the welded portion; and

a controller configured to communicate with the measuring unit, determine the resistance value of the welded portion by receiving the data obtained from the measuring unit, and determine whether a weak welding was performed by comparing the determined resistance value with a threshold resistance value,

wherein the measuring unit is configured to allow the resistance measuring probe to contact one end and the other end of the welded portion,

wherein the measuring unit comprises:

a flat cradle on which a subject is mounted;

an upper plate configured to be positioned on an upper portion having a predetermined separation distance from the flat cradle and includes a plurality of through holes into which the resistance measuring probe is insertable;

a lower plate configured to be positioned on a lower portion having a predetermined separation distance from the flat cradle and includes a plurality of through holes into which the resistance measuring probe is insertable;

a coupling unit configured to allow the flat cradle, the upper plate and the lower plate to be coupled to each other; and

a pair of resistance measuring probes configured to obtain data for determining the resistance value by contacting the welded portion,

wherein the coupling unit includes a coupling bar and a coupling screw,

wherein the flat cradle, the upper plate and the lower plate each has coupling holes at 4 edge portions, and

wherein the upper plate, the flat cradle and the lower plate are coupled as the coupling bar sequentially passes through coupling holes disposed on the upper plate, the flat cradle and the lower plate.