초록 ▼

In order to detect setting defects of a self-piercing rivet in a self-piercing rivet setting machine, on a graph having X-Y coordinates representing a rivet driven stroke and a rivet driving load, a normal upper limit curve 37 defining the upper limit of a normal setting range and a normal lower lim

In order to detect setting defects of a self-piercing rivet in a self-piercing rivet setting machine, on a graph having X-Y coordinates representing a rivet driven stroke and a rivet driving load, a normal upper limit curve 37 defining the upper limit of a normal setting range and a normal lower limit curve 38 defining the lower limit of the normal setting range are plotted to detect a conventionally detectable setting defects. Further, a defect upper limit curve 39 and a defect lower limit curve 41 which are obtained from an additional setting defect different from the conventionally detectable setting defects are plotted between the normal upper limit curve and the normal lower limit curve, so that the additional setting defect is detected when a plotted curve 45 of actual-measurement data of a rivet under a rivet driving operation lies between the defect upper and lower limit curves.

대표청구항 ▼

1. In a self-piercing rivet setting machine wherein a self-piercing rivet comprising a flange-shaped head and an annular leg extending downward from said head is driven into a plurality of workpieces by a punch and a die to outwardly expand and deform the edge of said leg while piercing said workpie

1. In a self-piercing rivet setting machine wherein a self-piercing rivet comprising a flange-shaped head and an annular leg extending downward from said head is driven into a plurality of workpieces by a punch and a die to outwardly expand and deform the edge of said leg while piercing said workpieces with said leg, so as to connect said workpieces with each other between said deformed leg and said head,a method for detecting a setting defect of the self-piercing rivet comprising the steps of: plotting a normal upper limit curve defining the upper limit of a normal setting range and a normal lower limit curve defining the lower limit of the normal setting range on a graph having X-Y coordinates representing a rivet driven stroke and a rivet driving load; during driving of the rivet, measuring the rivet driven strokes and rivet driving loads of the self-piercing rivet to plot them on said graph; and determining whether said plotted values would deviate from the values between said normal upper limit curve and said normal lower limit curve to detect a first setting defect of said self-piercing rivet, and wherein said method further comprises the steps of: plotting a defect upper limit curve and a defect lower limit curve between said normal upper and lower limit curves on said graph, said defect upper and lower limit curves being obtained from a second setting defect different from said first setting defect; and determining whether said plotted value of said driven self-piercing rivet lies between said defect upper limit curve and said defect lower limit curve to detect said second setting defect of said self-piercing rivet. 2. A method as defined in claim 1, wherein said second setting defect is caused by overturning of the self-piercing rivet in said punch.3. A method as defined in claim 1, wherein said second setting defect is caused by insufficient hardness of the self-piercing rivet.4. In a self-piercing rivet setting machine wherein a self-piercing rivet comprising a flange-shaped head and an annular leg extending downward from said head is driven into a plurality of workpieces by a punch and a die to outwardly expand and deform the edge of said leg while piercing said workpieces with said leg, so as to connect said workpieces with each other between said deformed leg and said head,a method for detecting a setting defect of the self-piercing rivet comprising the steps of: plotting a normal upper limit curve defining the upper limit of a normal setting range and a normal lower limit curve defining the lower limit of the normal setting range on a graph having X-Y coordinates representing a rivet driven stroke and a rivet driving load; during driving of the rivet, measuring the rivet driven strokes and rivet driving loads of the self-piercing rivet to plot them on said graph; and determining whether said plotted values would deviate from the values between said normal upper limit curve and said normal lower limit curve to detect a first setting defect of said self-piercing rivet, and wherein said method further comprises the steps of: storing a single defect curve pattern as a reference template, said defect curve pattern being obtained from a second setting defect different from said first setting defect; storing plural actual-measurement data over the entire single rivet driving operation as the actual-measurement data for a single frame, said actual-measurement data being obtained from said plotted value during driving of said self-piercing rivet; calculating respective differences between said reference template data and said single frame actual-measurement data; and integrating values based on said differences to determine said second setting defect on the basis of the magnitude of said integrated value. 5. A method as defined in claim 4, wherein said second setting defect is caused by overturning of the self-piercing rivet in said punch.6. A method as defined in claim 4, wherein said second setting defect is caused by insufficient hardness of the self-piercing rivet.7. In a self-piercing rivet setting machine wherein a self-piercing rivet comprising a flange-shaped head and an annular leg extending downward from said head is driven into a plurality of workpieces by a punch and a die to outwardly expand and deform the edge of said leg while piercing said workpieces with said leg, so as to connect said workpieces with each other between said deformed leg and said head,a method for detecting a setting defect of the self-piercing rivet comprising the steps of: plotting a normal upper limit curve defining the upper limit of a normal setting range and a normal lower limit curve defining the lower limit of the normal setting range on a graph having X-Y coordinates representing a rivet driven stroke and a rivet driving load; during driving of the rivet, measuring the rivet driven strokes and rivet driving loads of the self-piercing rivet to plot them on said graph; and determining whether said plotted values would deviate from the values between said normal upper limit curve and said normal lower limit curve to detect a first setting defect of said self-piercing rivet, and wherein said method further comprises the steps of: storing a single defect curve pattern as a reference template, said defect curve pattern being obtained from a second setting defect different from said first setting defect, and said reference template being composed of data varying in each of predetermined rivet driven strokes; recording actual-measurement data of the rivet driving load for the rivet driven stroke, as data varying in each of said predetermined rivet driven strokes, said actual-measurement data being obtained from said self-piercing rivet during driving of said rivet; and comparing said recorded data with said reference template data to detect said second setting defect on the basis of the degree that said recorded data approximates to said reference template data. 8. A method as defined in claim 7, wherein said second setting defect is caused by overturning of the self-piercing rivet in said punch.9. A method as defined in claim 7, wherein said second setting defect is caused by insufficient hardness of the self-piercing rivet.10. An apparatus for detecting a setting defect of a self-piercing rivet comprising a flange-shaped head and an annular leg extending downward from said head for use in a self-piercing rivet setting machine wherein the self-piercing rivet is driven into a plurality of workpieces by a punch and a die to outwardly expand and deform the edge of said leg while piercing said workpieces with said leg, so as to connect said workpieces with each other between said deformed leg and said head, said setting defect detecting apparatus being operable to display a normal upper limit curve defining the upper limit of a normal setting range and a normal lower limit curve defining the lower limit of the normal setting range on a graph having X-Y coordinates representing a rivet driven stroke and a rivet driving load; to measure the rivet driven strokes and rivet driving loads of the driving self-piercing rivet to plot them on said graph; and to determine whether said plotted values would deviate from the values between said normal upper limit curve and said normal lower limit curve to detect a first setting defect of said self-piercing rivet, andwherein said setting defect detecting apparatus is further operable: to display a defect upper limit curve and a defect lower limit curve which are obtained from a second setting defect different from said first setting defect, between said normal upper and lower limit curves on said graph; and to determine whether said plotted value of said driven self-piercing rivet lies between said defect upper limit curve and said defect lower limit curve to detect said second setting defect of said self-piercing rivet. 11. An apparatus as defined in claim 10, wherein said second setting defect is caused by overturning of the self-piercing rivet in said punch.12. An apparatus as defined in claim 10, wherein said second setting defect is caused by insufficient hardness of the self-piercing rivet.13. An apparatus for detecting a setting defect of a self-piercing rivet comprising a flange-shaped head and an annular leg extending downward from said head for use in a self-piercing rivet setting machine wherein the self-piercing rivet is driven into a plurality of workpieces by a punch and a die to outwardly expand and deform the edge of said leg while piercing said workpieces with said leg, so as to connect said workpieces with each other between said deformed leg and said head, said setting defect detecting apparatus being operable to display a normal upper limit curve defining the upper limit of a normal setting range and a normal lower limit curve defining the lower limit of the normal setting range on a graph having X-Y coordinates representing a rivet driven stroke and a rivet driving load; to measure the rivet driven strokes and rivet driving loads of the driving self-piercing rivet to plot them on said graph; and to determine whether said plotted values would deviate from the values between said normal upper limit curve and said normal lower limit curve to detect a first setting defect of said self-piercing rivet, andwherein said setting defect detecting apparatus is further operable: to store a single defect curve pattern obtained from a second setting defect different from said first setting defect, as a reference template; to store plural actual-measurement data obtained over the entire single rivet driving operation from said plotted value, as the actual-measurement data for a single frame: and to calculate respective differences between said reference template data and said single frame actual-measurement data and then integrate values resulted from said differences to determine said second setting defect on the basis of the magnitude of said integrated value. 14. An apparatus as defined in claim 13, wherein said second setting defect is caused by overturning of the self-piercing rivet in said punch.15. An apparatus as defined in claim 13, wherein said second setting defect is caused by insufficient hardness of the self-piercing rivet.16. An apparatus for detecting a setting defect of a self-piercing rivet comprising a flange-shaped head and an annular leg extending downward from said head for use in a self-piercing rivet setting machine wherein the self-piercing rivet is driven into a plurality of workpieces by a punch and a die to outwardly expand and deform the edge of said leg while piercing said workpieces with said leg, so as to connect said workpieces with each other between said deformed leg and said head, said setting defect detecting apparatus being operable to display a normal upper limit curve defining the upper limit of a normal setting range and a normal lower limit curve defining the lower limit of the normal setting range on a graph having X-Y coordinates representing a rivet driven stroke and a rivet driving load; to measure the rivet driven strokes and rivet driving loads of the driving self-piercing rivet to plot them on said graph; and to determine whether said plotted values would deviate from the values between said normal upper limit curve and said normal lower limit curve to detect a first setting defect of said self-piercing rivet, andwherein said setting defect detecting apparatus is further operable: to store a single defect curve pattern as a reference template, said defect curve pattern being obtained from a second setting defect different from said first setting defect, and said reference template being composed of data varying in each of predetermined rivet driven strokes; to record actual-measurement data of the rivet driving load for the rivet driven stroke, as data varying in each of said predetermined rivet driven strokes, said actual-measurement data being obtained from said driving self-piercing rivet; and to compare said recorded data with said reference template data to detect said second setting defect on the basis of the degree that said recorded data approximates to said reference template data. 17. An apparatus as defined in claim 16, wherein said second setting defect is caused by overturning of the self-piercing rivet in said punch.18. An apparatus as defined in claim 16, wherein said second setting defect is caused by insufficient hardness of the self-piercing rivet.