Patent Application
20100307212
This invention relates to a crimping apparatus and methods for applying a press force and a part of the press force is separately applied as a core crimp force, more particularly, a crimping apparatus applies a press force and a part of the press force is applied separately as a core crimp force that is applied from a ram to a load pin to an independently moving core plate to produce a core crimp portion that connects the terminal to the wire conductor, and the applied core crimp force is transferred from the core crimp portion to a core plate to a load pin and into the ram.
It is known, according to prior art U.S. Pat. No. 5,101,651 issued on Apr. 7, 1992 and referring to
It is also known to measure a press force applied by the die press during the crimping cycle to assess the quality of a core crimp portion that connects a wire conductor to a terminal. The press force includes a force component known as the core crimp force that is needed to produce a core crimp portion that crimps a terminal to an exposed portion of the wire conductor during the crimping cycle. Measurement of the press force does not allow a consistent, reliable quality decision regarding the core crimp portion to be rendered, especially for a size of wire conductor of less then or equal to 20 gauge connected to a corresponding terminal.
It is desirable to render a consistent, reliable quality decision regarding the core crimp portion produced after the core crimp force is applied during the crimping cycle, especially for a terminal crimped to a size of wire conductor of less then or equal to 20 gauge. For example, the quality defects of a wire strand missing in the core crimp portion and wire insulation contained in the core crimp portion are important to detect to ensure that the mechanical and electrical integrity of the crimp connection of the terminal to the wire conductor is not impaired. Because smaller gauge wire of less than 20 gauge includes wire strands having a smaller cross sectional area than similar strands of larger gauge wire, detecting the quality defect of a strand of wire conductor missing from the core crimp portion becomes increasingly difficult. An undetected core crimp portion that is defective may produce an undesired effect of downstream quality issues when the terminal connected to the wire conductor is manufactured into a wiring harness.
Therefore, what is needed is a crimping apparatus that is configured to apply a core crimp force to produce a reliable core crimp portion and render a quality decision that accurately reflects the quality of the produced core crimp portion during the crimping cycle, especially for a terminal crimped to a size of wire conductor of less then or equal to 20 gauge.
Analysis of an applied core crimp force that produces a reliable core crimp portion connecting the terminal to the wire conductor is found to be a suitable quality indicator for detecting the defects of a missing wire conductor strand contained in the core crimp portion and wire insulation contained in the core crimp portion, especially for smaller gauge wire having a size of less than 20 gauge connected to a corresponding terminal. Because the applied core crimp force is a suitable quality indicator of core crimp portion defects, it is desirable to apply and sense the actual core crimp force that produces the core crimp portion apart, or separate from, the applied press force of the die press and the remaining force components that are derived from the applied press force during the crimping cycle.
In accordance with one embodiment of the invention, a crimping apparatus includes a die assembly. The die assembly includes a die defining a cavity and the cavity includes a core plate having independent movement within the cavity. The core plate includes a first core plate end and a second core plate end remote from the first core plate end. The crimping apparatus includes a ram assembly for applying a press force to the die assembly. The ram assembly includes a ram and a load pin being in force connection with the ram. The load pin has a first pin end and a second pin end remote from the first pin end. The first pin end is proximate to the ram and the second pin end extends away remote from the ram assembly into the die assembly being proximate to the first core plate end. The load pin is in force connection with the core plate. A wire conductor is disposed in a terminal located on a terminal plate pad in the crimping apparatus proximate to the second core plate end. The press force will be applied by the ram and the load pin will engage the first core plate end and the second core plate end will engage the terminal plate pad and the wire conductor disposed in the terminal therebetween. A part of the press force will be separately applied as a core crimp force and produce a core crimp portion that connects the terminal to the wire conductor and the applied core crimp force is transferred from the core crimp portion to the core plate to the load pin into the ram.
In accordance with another embodiment of the invention, a method of applying a press force includes the step of providing a crimping apparatus configured to apply a press force. A part of the press force is applied separately as a core crimp force. A further step includes providing the wire conductor disposed in the terminal to the crimping apparatus. Yet a further step includes applying the core crimp force to the wire conductor disposed in the terminal producing a core crimp portion that connects the terminal to the wire conductor.
In accordance with yet a further embodiment of the invention, a manufacturing process method for connecting a wire conductor to a terminal includes the step of providing the wire conductor and the terminal. A further step in the method is disposing the wire conductor in the terminal. An additional step is applying a press force, and a part of the press force is separately applied as a core crimp force producing a core crimp portion connecting the terminal to the wire conductor. A further step is sensing the applied core crimp force. The method also includes measuring the sensed core crimp force. Yet a further step includes evaluating a measurement of the core crimp force to render a quality decision on the core crimp portion.
This invention will be further described with reference to the accompanying drawings in which:
In accordance with a preferred embodiment of this invention, referring to
Crimping is generally known as joining two pieces of metal or other malleable material by deforming one or both materials to hold the other. The bend or deformity in the metal or other malleable material is generally known as a crimp. A terminal generally includes any device attached to a wire conductor that facilitates connection with another conductor. According to the embodiment shown in
Prior to the application of the press force by the apparatus, the wire conductor and terminal are provided to the apparatus. Typically, the terminal is provided to the apparatus on a wire frame. Terminal 12 includes a first terminal portion 16 and a second terminal portion 18. Wire conductor 14 includes an exposed wire portion 20 and an insulated wire portion 22. Insulated wire portion 22 has wire insulation disposed surrounding wire conductor 14. Exposed wire portion 20 is disposed in first terminal portion 16 and insulated wire portion 22 is disposed in the second terminal portion 18. With application of the press force, an insulation crimp portion is produced by an insulation crimp force at insulated wire portion 22 disposed in second terminal portion 18. A part of the press force separately applied as the core crimp force produces core crimp portion of the exposed wire portion 20 disposed in first terminal portion 16. It should be understood the core crimp portion and the insulation crimp portion are formed within the terminal and are hidden from view in the
The press force is the total force applied by the ram assembly to the die assembly of the apparatus. Several main force components make up the press force. A first main force component is the core crimp force applied to crimp the exposed wire portion is disposed in first terminal portion. A second main force component is the insulation crimp force to crimp the insulated wire portion disposed in the second terminal portion. A third main force component is the force applied to a terminal cut-off punch where the terminal is cut free from the wire frame after the crimping cycle. The forth main component force is the force applied to the terminal pad where the uncrimped terminal disposed in the wire conductor lie in the die press. Because the apparatus creates large forces when the press force is applied, it is desirable to securely support the apparatus to facilitate controlled movements and forces during the crimping process. This can be achieved, for instance, by securely mounting the apparatus to the floor.
Apparatus 10 is constructed in a manner to be able to sustain repeated applications of a press force and is typically constructed of metal, preferably steel. Apparatus 10 includes a die assembly 24 and a ram assembly 26 opposed to the die assembly 24.
Referring to
Typically, a corresponding terminal for a wire conductor is suitably designed to cover a corresponding two gauge size range. For example, a corresponding 20 gauge terminal may be used to connect to a 20 or 22 gauge wire conductor.
Core plate 32 has a slot 38 intermediate first core plate end 34 and second core plate end 36. A fastener 40 is disposed in slot 38 to secure core plate 32 in cavity 30 such that core plate has independent movement in cavity 30 about fastener 40 along slot 38 parallel to length L of core plate 32, but not along width W or thickness T. Preferably, the fastener is a bolt having screw threads that are secured into a threaded hole in the die. Second core plate end 36 of core plate 32 includes a cutout 42. The cutout is configured to provide the necessary shape to form the core crimp portion when the core crimp force is applied from the ram assembly. Terminal 12 and wire conductor 14 are disposed on a terminal plate pad 44 underlying core plate 32 and an insulation plate 46. Exposed wire portion 20 is disposed in first terminal portion 16 and underlies the second core plate end 36 and insulated wire portion 22 is disposed in the second terminal portion 18 that underlies an insulation plate end 48 of insulation core plate 46. Referring to
Insulation plate 46 is adjacent core plate 32 in cavity 30 of die assembly 24. Similar to the core plate, the insulation plate about fits the cavity along a width and a thickness of the insulation plate. Insulation plate 46 defines a hole 50. Fastener 40 is disposed in hole 50 of insulation plate 46 to secure insulation plate 46 in cavity 30. Hole 50 is large enough to allow passage of fastener 40, but not so large as to allow substantial movement of insulation plate 46 about hole 50 with application of the insulation crimp force. Fastener 40 is utilized to secure both core plate 32 and insulation plate 46 in die 28. A component of the press force applied as the insulation crimp force applied through insulation plate 46 produces the insulation crimp portion of insulated wire portion 22 disposed in second terminal portion 18. The length, width, and thickness of the insulation plate is similar to that of the core plate. Insulation plate 46, similar to core plate 32, includes a cutout 52. Cutout 52 is disposed on an insulation plate end 49 and is proximate to second core plate end 36. The cutout in the insulation plate has a similar function as the cutout in the core plate and is used to configure the insulation crimp portion of the terminal to the wire conductor when the crimp force is applied to the die assembly. Insulation plate 46 does not have substantial movement in cavity 32 of die 28 during the crimping cycle of the apparatus.
Alternately, a spacer intermediate the core plate and the insulation plate is suitable to space apart the core plate from the insulation plate in the cavity and is dependent on the distance needed between the core crimp portion and the insulation crimp portion to connect the terminal to the wire conductor. The spacer has similar dimensions to that of the core plate and insulation plate. The spacer defines a hole, similar to that of insulation plate and having a similar hole dimension. The spacer is secured to the die by the fastener disposed in the hole of the spacer along with the core plate and the insulation plate. It is desirable to have the spacer fit the cavity so as to not have substantial independent movement of the spacer in the cavity of the die assembly during the crimping cycle, similar to that of the insulation plate.
Die assembly 24 further includes a nail head 54 in force connection with ram assembly 26. A first portion 56 of nail head 54 is supported in ram head 60 and a second portion 58 of nail head 54 is supported in die 28. Nail head 54 transmits the press force supplied from ram assembly 26 to die assembly 24, but does not include transmission of the core crimp force. The die is constructed to help support and provide structural integrity to the core plates, insulation plate, and the nail head in the die assembly of the crimping apparatus during the crimping cycle and when no press force is applied.
Ram assembly 26 includes a ram 62, a sensor or load cell 64, and a load pin 66, and the ram head 60. Ram 62 supplies the press force to die assembly 24 in apparatus 10. Load cell 64 is secured to ram 62, preferably by a bolt (not shown) disposed in ram 62 that threads into load cell 64. Load cell 64 senses the core crimp force applied to the core crimp portion. The ram head is constructed to help support and provide structural integrity to the load cell, load pin, and nail head in the ram assembly of the crimping apparatus during the crimping cycle and when no press force is applied.
Preferably, the load cell is a piezoelectric design where the applied core crimp force is sensed and an electrical output (not shown) is produced. Electrical output (not shown) is a voltage having a value proportional to the applied core crimp force. The electrical output of the load cell may be measured and evaluated in the apparatus or remote from the apparatus. A suitable load cell element is commercially available from Kistler under the trade name designation #9219 Piezoelectric Transducer.
Load pin 66 includes a shaft 68 having a longitudinal axis A. Pin 66 has a first pin end 70 and a second pin end 72 remote from first pin end 70. Shaft 68 has a first width W1 and the first pin end 70 has a second width W2 and the second width W2 is greater than first width W1. Pin 66 is supported in apparatus 10 by the design of ram head 60 around first pin end 70. Pin 66 is connected to load cell 64, preferably with a threaded hex bolt secured to the load cell at the first pin end. Second pin end 68 extends away remote from ram assembly 26 into ram head 60 and into die assembly 24. Second pin end 72 is proximate to first core plate end 34. Core plate 32 is in force connection with pin 66.
Alternately, if the load cell secured to the ram is not used, the pin is configured to be in direct connection with the ram.
Ram 62, load cell 64, pin 66, and core plate 32, and core crimp portion are axially aligned along axis A. Core plate 32 extends axially in die assembly 24 along the length L of core plate 32. Core plate 32 has axial movement in die 28 along slot 38. The independently moving core plate does not require a lubricant to assist, or enable axial movement in the cavity during the crimping cycle.
Load pin 66 further includes a first pin portion 74 that is in force connection and in proximity to a second pin portion 76. First pin portion 74 is independent of second pin portion 76. Ram assembly 26 includes first pin portion 74 and die assembly 24 includes second pin portion 76. Ram assembly 26 is independent form die assembly 24, such that die assembly 24 along with second pin portion 76, may be removed from ram assembly 26 of apparatus 10. For example, latches (not shown) on the die assembly connecting the die assembly to the ram assembly may be unlatched, allowing the die assembly to be pulled out and away from the apparatus. Removal of the die assembly allows usage of the die assembly in a different apparatus. When die assembly 24 is replaced into apparatus 10, second pin portion 76 returns to be axially aligned with first pin portion 74.
Referring to
For example, as shown in
First crimp height means 78 is also effective for adjustment of first pin portion 74 in relation to second pin portion 76 to achieve force connection between pin portions 74, 76 when die assembly 24 is replaced back into apparatus 10. Referring to
When not in operation, referring to
In operation, referring to
The applied core crimp force that produces the core crimp portion is then subsequently transferred in a axial direction opposed to the applied core crimp force and away from the core crimp portion. The applied core crimp force is axially transferred from the core crimp portion to core plate 32 to load pin 66 to load cell 64. The load cell senses the applied core crimp force. Referring to
As the core crimp force produces the core crimp portion, the insulation core crimp force is applied to produce an insulation core crimp portion that connects second terminal portion 18 to insulated wire portion 22.
The core crimp force is separately applied apart from the press force, the remaining component forces of the press force, and the force noise during the crimping cycle. The core crimp force is also sensed apart from the other structure of the crimping apparatus with substantially no loss of the core crimp force to the structure of the crimping apparatus during the transfer from the core crimp portion to the load cell.
The measurement of the core crimp force data sensed by the load cell may be recorded and evaluated to render a quality decision on the core crimp portion. The core crimp force measurement data may be evaluated by a processor on the apparatus or remote from the apparatus. The quality defects of a wire strand missing in the core crimp portion and wire insulation contained in the core crimp portion are important to detect to ensure that the mechanical and electrical integrity of the crimp connection of the terminal to the wire conductor is not impaired. Because smaller gauge wire of less than 20 gauge includes wire strands having a smaller cross sectional area than similar strands of larger gauge wire, detecting the quality defect of a strand of wire conductor missing from the core crimp portion becomes increasingly difficult. An undetected core crimp portion that is defective may produce an undesired effect of downstream quality issues when the terminal connected to the wire conductor is manufactured into a wiring harness.
Typically, the press force applied to crimp a terminal to a wire conductor of less than 20 gauge is in a range of 4500 to 5000 Newtons. In comparison, the core crimp force to crimp a terminal to a wire conductor of a size of 20 gauge or less is about 3600 to 4000 Newtons. Detecting a defective core crimp portion from an acceptable core crimp portion by measuring the press force in a 26 gauge wire conductor in a 26 gauge terminal yielded a 29.3 Newton nominal force delta with the defective nominal force curve being lower than the acceptable nominal force curve. The defective core crimp portion has one missing wire strand missing from the core crimp portion.
Referring to
After measurement of the core crimp force and evaluation of the measurement data to render a quality decision of an acceptable core crimp portion or a defective core crimp portion, the terminal may be trimmed from a lead frame, the terminals connected to wire conductors having the acceptable core crimp portions may be separated from terminals connected to wire conductors having defective core crimp portions. Moreover, only the terminals connected to wire conductors having the acceptable core crimp portions may be used in a later manufacturing operation to construct a wire harness.
Alternately, the load cell may be disposed in the die in the die assembly. With the load cell disposed in the die, each die placed in a crimping apparatus would require a load cell if the core crimp force is to be measured.
In a further alternate embodiment, the apparatus may be designed such that the load pin is disposed through an opening in the nail head.
In another alternate embodiment, the insulation core crimp portion may be produced, sensed, and measured in a similar manner to that of the core crimp portion, described herein.
Alternately, if the core crimp force and the insulation core crimp force are sensed and measured in the same crimping apparatus, two sensors are required. One sensor measures the core crimp force and the other sensor measures the insulation core crimp force. The design would require alternation to stagger the sensors due to their physical size while allowing a pin configuration that allows both the core crimp force and the insulation core crimp force to be adequately measured by each respective sensor.
Alternately, additional load cells may be utilized in the crimping apparatus for measurement of the crimp force, terminal pad force, or other forces applied during the crimping operation of the crimping apparatus.
Alternately, the terminal may include a plurality of crimp portions as necessary dependent on the design of the terminal to connect the terminal to the wire and the press may have a plurality of core plates and insulation plates.
In yet a further alternate embodiment, the press force may be measured and the other elements of the press force be subtracted leaving the core crimp force. Because the amount of force noise associated with applying the press force has variation with each application of the press force, obtaining core crimp force data that reliably detects actual core crimp portion defects is not as predictable with this embodiment, especially for defective core crimp portions of terminals connected to wire conductors having a size of less than 20 gauge.
Thus, the invention provides a crimping apparatus, a method of applying a force, and a manufacturing process method where a press force is applied and a portion of the press force is separately applied as a core crimp force to crimp a terminal to a wire conductor. The applied core crimp force is separated from the applied press force in the crimping apparatus to crimp a terminal to a wire conductor by a load pin and an independently moving core plate in a cavity of the die in the die assembly and the remaining components of the press force are applied to the die assembly through the nail head from the ram assembly to the die assembly. The separation of the core crimp force by the load pin and the independently moving core crimp plate allows sensing of the core crimp force apart from the remaining force components that make up the press force. The axial alignment of the crimp portion, the load cell, the load pin, the core plate allow for the core crimp force to effectively applied to and transferred from the core crimp portion to the load cell for measurement. Because of the separately applied and sensed core crimp force, evaluation of the core crimp force measurements allow acceptable core crimp portions to be detected from the defective core crimp portions that include wire strands of wire conductor found in the core crimp portion and insulation found in the core crimp portion, especially for smaller gauge wire conductors having a size of less than 20 gauge disposed in a corresponding terminal. The load cell for sensing the core crimp force is disposed in the ram assembly as opposed to the die assembly that results in a reduced amount of sensors required to measure the core crimp force, decreasing material costs. Each apparatus can utilize multiple dies using only one load cell sensing element. The load pin has a first pin portion included in the ram assembly and a second pin portion in the die assembly and the ram assembly is independent from the die assembly allowing the die assembly along with the second pin portion to be easily removed from the crimping apparatus and be replaced in a different apparatus. A higher core crimp force delta between an acceptable versus a defective core crimp portion over that of measuring the press force provides a higher confidence level that a measured core crimp portion defect reflects an actual core crimp portion defect. Directly measuring the core crimp force provides a higher confidence level of detecting actual core crimp portion defects than measuring the press force and subtracting out the components of the press force leaving the core crimp force, especially for terminals connected to wire conductors having a size of less than 20 gauge.
While this invention has been described in terms of the preferred embodiment thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.
