Terminal crimping apparatus

Abstract: A terminal crimping apparatus comprises a pressure receiving part (A1, A2) provided at a tip thereof with a pressure receiving surface (R3) for receiving a crimped terminal (1) having a barrel (11,12) whose tips are chamfered at outer peripheral sides thereof, and a caulking part (C1, C2) having a caulking surface (E) adapted to receive the tip of the pressure receiving part (A1, A2), for caulking the barrel (11,12) of the crimped terminal (1) between the caulking surface (E) and the pressure receiving surface (R3) of the pressure receiving part (A1, A2) such that one tip (11a, 12a) of the barrel overlaps the other (11b, 12b). In one aspect of the invention, the caulking part (C1, C2) has two rounding surfaces (R1, R2) smoothly integrating with each other so as to form a step portion (D) having one end located at the deepest point (P) formed at a middle portion of the caulking surface. The step portion (D) has a difference (H) in level at least equal to the thickness of the tips (t) of the barrel. According to another aspect of the invention, the deepest point (Q) of the pressure receiving part (A1, A2) and the deepest point of the caulking part (C1, C2) are located along a virtual line (L3) parallel with a symmetrical line (L2) of the barrel.

Description: The present invention relates to the use of a terminal crimping apparatus for crimping a crimped terminal of the opened barrel type to an end of an electric wire. As an example of a crimped terminal to be crimped to an end of an electric wire, there is conventionally known a crimped terminal of the opened barrel type. As shown in Fig. 1, such a crimped terminal of the opened barrel type has a wire barrel 11 to be crimped to a conductor W1 at an end of an electric wire W, and an insulation barrel 12 to be crimped to a coated end W2 of the electric wire W. Each of the barrels 11, 12 has a substantially U-shaped section and is of linear symmetry. A crimped terminal 1 (See Fig. 2) can be crimped to an end of the electric wire W in the following manner. With the conductor W1 and the coated end W2 of the electric wire W respectively introduced into the wire barrel 11 and the insulation barrel 12, the barrels 11, 12 are respectively caulked by two pairs of crimpers 13 and anvils 14 of a terminal crimping apparatus, each pair of crimper 13 and anvil 14 being vertically disposed with each of the barrels 11, 12 sandwiched therebetween. As a method of crimping the crimped terminal 1, there is known a so-called overlap crimping method, as shown in Fig. 4, by which one tip 111, 121 of each of the barrels 11, 12 overlaps the other tip 112, 122 of the barrels 11, 12 (Japanese Patent Unexamined Publication Serial No. 3-165478, Japanese Patent Unexamined Publication Serial No. 3-291881, Japanese Patent Examined Publication Serial No. 55-37840, and Japanese Utility Model Examined Publication Serial No. 52-24784). To carry out the overlap crimping above-mentioned, each of the crimpers 13 has a caulking surface for pushing the barrel 11 or 12, and this caulking surface has a step portion 13c, a first round portion 13a and a second round portion 13b, the first and second round portions 13a, 13b smoothly integrating with each other through the step portion 13c, as shown in Fig. 2. The step portions 13c are formed at positions biased toward the second round portions 13b with respect to the center portions 13d of the caulking surfaces. On the other hand, each of the anvils 14 has a pressure receiving surface 14a for receiving the barrel 11 or 12. The pressure receiving surfaces 14a are arcuate as depressed downwardly with respect to the drawing plane of Fig. 2 such that the barrels 11, 12 are adapted to be received. When the crimpers 13 and the anvils 14 press the barrels 11, 12 by pinching the barrels 11, 12 therebetween, one tip 111, 121 of each of the barrels 11, 12 moves along the corresponding first round portion 13a while the other tip 112, 122 moves along the corresponding second round portion 13b, utilizing the step portions 13c at the boundaries between these round portions 13a, 13b, so it is possible to caulk one tip 111, 121 of each of the barrels 11, 12 as overlapping the outer peripheral sides of the other tip 112, 122 respectively. In the conventional overlap crimping above-mentioned, the following has been presumed. That is, when the crimpers 13 and the anvils 14 press the barrels 11, 12 by pinching the barrels 11, 12 therebetween, the tips 111, 121 of the barrels 11, 12 are so deformed as to follow the corresponding first round portions 13a while the other tips 112, 122 are so deformed as to follow the corresponding second round portions 13b so that the tips 111, 121 ultimately overcome the step portions 13c and overlap the outer peripheral sides of the other tips 112, 122. Dependent on the shapes of the barrels 11, 12 or the shapes of the caulking surfaces of the crimpers 13, there are instances where the tips 111, 121 of the barrels 11, 12 do not overlap the other tips 112, 122 but abut thereon, as shown in Fig. 4. This disadvantageously generates burrs B on those portions of the barrels 11, 12 which correspond to gaps between the crimpers 13 and the anvils 14. The inventor of the present application has studied what might be the cause of such defective crimping, and found the following fact. Referring to Figs. 5A to 5D, the following will discuss the mechanism for crimping the barrels 11, 12 by the crimpers 13 and the anvils 14. When the crimpers 13 approach the anvils 14, the tips 111, 121 and the other tips 112, 122 of the barrels 11, 12 abut each other in the openings of the crimpers 13. The shapes of the caulking surfaces and the opening widths at the vicinity of the openings of the crimpers 13 are determined such that the tips 111, 121 and the other tips 112, 122 are so deformed as to face each other. Accordingly, the tips 111, 121 and the other tips 112, 122 abut each other while contacting with the first round portions 13a. As the crimpers 13 approach nearer the anvils 14 as shown in Fig. 5B, the tips 111, 121 are so deformed as to follow the first round portions 13a and the other tips 112, 122 are so deformed as to follow the second round portions 13b. As shown in Fig. 5c, the further caulking process from the state shown in Fig. 5B normally causes the tips 112, 122 to overlap the tips 111, 121 as the other tips 112, 122 are pressed downwardly by the step portions 13c when the tips 111, 121 and the tips 112, 122 follow respectively the corresponding round portions 13a, 13b to a certain extent, so that the tips 111, 121, as shown in Fig. 5D, ultimately overcome the step portion 13c, thus completing the crimping processing. In view of the foregoing, the inventor has found that the cause of defective crimping resides in the fact that the caulking step has been advanced without release of the state in which the tips 111, 121 abut the other tips 112, 122 (Fig. 5A). Accordingly, what is really needed is a terminal crimping apparatus that can prevent the tips of a barrel from abutting on each other, thus preventing a crimped terminal from being defectively crimped. In crimping the crimped terminal 1, it is required that the electrical connection between the conductor W1 of the electric wire W and the wire barrel 11 is perfectly assured and that there is provided a crimping strength substantially equal to the tensile strength of the electric wire W. Therefore, the crimping quality is conventionally checked by measuring the crimp height H of the crimped terminal 1 (e.g., Japanese Patent Unexamined Publication Serial No. 2-257001). Fig. 6 is a perspective view of a measuring device 2 for measuring the crimp height H. The measuring device 2 comprises a frame 20, a dial gauge 21 supported by the frame 20, a block-like movable contact piece 22 disposed at the tip of a measuring head of the dial gauge 21, and a block-like stationary contact piece 23 disposed opposite to and under the movable contact piece 22. As shown in Fig. 7, a measuring surface 22a of the movable contact piece 22 and a measuring surface 23a of the stationary contact piece 23 are horizontal and parallel to each other. The crimp height H is measured in the following manner. As maintained in a posture in a crimping step, the crimped portion X of the crimped terminal 1 is held by and between the measuring surfaces 22a, 23a, and the scale on the dial gauge 20 is then read. To measure the accurate crimp height H, it is required that the crimped portion X of each of the barrels 11, 12 is clamped between the measuring surfaces 22a, 23a while maintaining each of the barrels 11, 12 in a caulked posture. In the conventional overlap crimping, however, a line segment L, which connects a contact point S1 where the measuring surface 22a of the movable contact piece 22 comes in contact with the crimped portion X to a contact point S2 where the measuring surface 23a of the stationary contact piece 23 comes in contact with the crimped portion X is inclined at a predetermined angle  with respect to the clamping direction of the crimped terminal 1 by the contact pieces 22, 23, or the perpendicular direction, as shown in Fig. 7. Accordingly, when the crimped portion X is clamped between the contact pieces 22, 23, a moment of rotation is inevitably applied to the crimped terminal 1, causing the crimped terminal 1 to be rotated around the electric wire W. This may disadvantageously produce a measuring error, thus failing to make an accurate judgment of whether the crimping is good or defective. Accordingly, what is needed is a means of accurately measuring the crimp height of the crimped terminal. The present invention is directed to the use of a terminal crimping apparatus that satisfies these needs. In accordance with the present invention, there is provided the use in crimping a crimped terminal having a barrel whose tips are chamfered at outer peripheral sides thereof to an end of an electric wire, of a terminal crimping apparatus comprising: pressure receiving means provided at a tip thereof with a pressure receiving surface for receiving the crimped terminal; and caulking means having a caulking surface adapted to receive said tip of said pressure receiving means, for caulking the barrel of the crimped terminal between said caulking surface and said pressure receiving surface of said pressure receiving means such that one tip of the barrel overlaps the other tip of the barrel; wherein said caulking means has two rounding surfaces smoothly integrating with each other so as to form a step portion having one end located at the deepest point formed at a middle portion of said caulking surface, and said step portion has a difference in level at least equal to the thickness of the tips of the barrel. Preferably, a deepest point of said pressure receiving means and said deepest point of said caulking means are located along a virtual line parallel with a symmetrical line of the barrel. According to an aspect of the present invention, when a barrel of a crimped terminal is caulked, one tip of the barrel can be brought into collision with the step portion, and the other tip can be brought into collision with a vicinity of the step portion of the caulking surface. This prevents the one tip of the barrel from abutting on the other tip thereof, thus preventing the barrel from being crimped to an electric wire with the both tips of the barrel abutting on each other. When the crimping step further proceeds, the other tip of the barrel can be securely guided to the inner peripheral side of the one tip of the barrel, in that the barrel tips are chamfered. When the crimping step further proceeds, the other tip of the barrel can readily get over the step portion in that the other tip of the barrel is chamfered and that the difference in level is set based on the thickness of each of the barrel tips. Accordingly, the other tip of the barrel can securely overlap the one tip, thus securely preventing the occurrence of defective crimping. Preferably, a virtual line connecting the deepest point of a pressure receiving surface for receiving a barrel, to the deepest point of a caulking surface for caulking the barrel, is parallel with and opposite to the axis of linear symmetry of the barrel. Accordingly, the crimped portion of a barrel is caulked such that the portions thereof along the axis of linear symmetry project most. Therefore, even though the crimped portion of the barrel is held by a measuring device while maintaining the barrel in a caulked posture, no moment of rotation is applied to the crimped portion of the barrel. This prevents the crimped terminal from being unexpectedly rotated. Thus, the crimp height can be accurately measured. It is therefore possible to accurately judge whether the crimping is good or defective. These features, objects and advantages of the present invention will be more fully apparent from the following detailed description set forth below when taken in conjunction with the accompanying drawings. By way of example only, a specific embodiment of the present invention will now be described, with reference to the accompanying drawings, in which:- Figure 1 is a perspective view of a conventional crimped terminal; Figure 2 is a schematic enlarged view of main portions of a conventional terminal crimping apparatus; Figure 3 is a perspective view of a crimped terminal which has been crimped to an electric wire by the conventional terminal crimping apparatus; Figure 4 is a section view of a terminal portion crimped by the conventional terminal crimping apparatus; Figure 5A to Figure 5D are schematic enlarged views of a crimped terminal illustrating a conventional crimping mechanism with the passage of time; Figure 6 is a perspective view of a measuring device for measuring the crimp height of a crimped portion of a terminal; Figure 7 is a schematic enlarged view of the main portions of the crimp height measuring device in Figure 6; Figure 8 is a side view of a terminal crimping apparatus for use in an embodiment of the present invention; Figure 9 is a schematic enlarged view of the main portions of the terminal crimping apparatus in Figure 8; Figure 10 is an exploded perspective view of the main portions of the terminal crimping apparatus in Figure 8; Figure 11 is an enlarged section view of the main portions of a crimped terminal which can be applied to the present invention; Figure 12A to Figure 12C are schematic enlarged views of a crimped terminal illustrating a crimping mechanism with the passage of time; and Figure 13 is a schematic enlarged view illustrating how the crimp height of a crimped terminal is measured. Referring to Fig. 8, a terminal crimping apparatus for use in a preferred embodiment of the present invention, has a frame 42 carried by a base 41. The frame 42 carries a column 43 on which in turn is mounted a hydraulic cylinder 44 directed downwardly. The hydraulic cylinder 44 has a rod 45 having a tip to which is connected a press ram 46. The press ram 46 is adapted to be moved up and down along a guide surface 47 on the frame 42. Crimpers C1, C2 are attached to the lower end of the press ram 46. Secured to the base 41 are anvils A1, A2 which are adapted to caulk a crimped terminal 1 of the opened barrel type, in cooperation with the crimpers C1, C2. The crimper C1 and the anvil A1 are disposed for caulking a wire barrel 11 of the crimped terminal 1, and the crimper C2 and the anvil A2 are disposed for caulking an insulation barrel 12 of the crimped terminal 1. In this embodiment, the terminal crimping apparatus has a terminal chain reel 48. The terminal chain reel 48 holds crimped terminals 1 as connected in the form of a chain or a belt. A terminal chain guide 49 is disposed between the terminal chain reel 48 and the anvils A1, A2. The chain-like crimped terminals 1 held by the terminal chain reel 48 are delivered to the anvils A1, A2 through the terminal chain guide 49. A feed claw 50 is disposed at the downstream end of the terminal chain guide 49 for feeding, one by one, the crimped terminals 1 as connected in the form of a chain, toward the anvils A1, A2. With the wire barrel 11 and the insulation barrel 12 of a crimped terminal 1 respectively mounted on the anvils A1, A2, the mechanism above-mentioned is operated to vertically move the crimpers C1, C2 to caulk the barrels 11, 12 so that the crimped terminal 1 can be crimped to the conductor W1 and the coated end W2 of the electric wire W. The terminal crimping apparatus above-mentioned has excellent mechanisms including a mechanism for adjusting the crimp height of a crimped terminal 1. Except for the arrangements of the crimpers C1, C2, the anvils A1, A2 and the like to be discussed later, this terminal crimping apparatus is arranged in the same manner as the apparatus disclosed in US Patent Serial No. 4,587,725 by the applicant of the present application. Accordingly, a detailed description of this apparatus is here omitted. Referring to Figs. 9 and 11, the barrel 11 of the crimped terminal 1 has a pair of barrel claws lla, llb and the barrel 12 of the crimped terminal 1 has a pair of barrel claws 12a, 12b. Each of the barrels 11, 12 has a substantially U-shaped section. Each of one barrel claws 11a, 12a and each of the other barrel claws 11b, 12b are substantially symmetric with respect to an axis of linear symmetry L2 which extends in the perpendicular direction (See Fig. 9). Each of the barrel claws 11a, 11b is provided on the outer peripheral side of the tip thereof with a chamfered surface llc, and each of the barrel claws 12a, 12b is provided on the outer peripheral side of the tip thereof with a chamfered surface 12c (See Fig. 11). The sizes of each of the chamfered surfaces 11c, 12c are set such that the tip thickness t of each of the barrels 11, 12 is equal to, for example, about a half of the entire thickness T of each of the barrels 11, 12. Referring to Fig. 9, the crimper C2 has a caulking surface E for pushing the insulation barrel 12, and the caulking surface E has a step portion D and at least two round portions R1, R2 smoothly integrating with each other through the step portion D. On the other hand, a pressure receiving surface R3 of the anvil A2 opposite to the two round portions R1, R2, is arcuate as concaved downwardly on the drawing plane of Fig. 9 such that the barrel 12 is adapted to be received. The step portion D of the crimper C2 is formed substantially at the center of the caulking surface E, i.e., on an extension line of the axis of linear symmetry L2 of the insulation barrel 12. Further, the step portion D is inclined at a predetermined angle  (e.g., 45°) with respect to the perpendicular direction. The step portion D has one end which is located at the deepest point (apex) P formed at the center of the caulking surface E. The difference in level h between the step portion D and other caulking surface E, is in the range from 1t to 1.5t where t refers to the tip thickness of the insulation barrel 12. Further, provision is made such that a line segment L3 connecting the deepest point (apex) P of the caulking surface E of the crimper C2 to the deepest point (bottom) Q of the pressure receiving surface R3 of the anvil A2, is perpendicular, i.e., parallel with the axis of linear symmetry L2 of the insulation barrel 12. Likewise in the prior art, the shape of the caulking surface E and opening width at the vicinity of the opening of the crimper C2 are determined such that each of the tips 11a, 12a and the other tip 11b, 12b respectively are so deformed as to face each other. The crimper C1 and the anvil A1 for caulking the wire barrel 11 have arrangements which correspond to the sizes of the conductor W1 of the electric wire W and which are respectively similar to those of the crimper C2 and the anvil A2 for caulking the insulation barrel 12. According to the arrangement above-mentioned, when the crimped terminal 1 is previously fed to the anvils A1, A2 from the terminal chain reel 48 shown in Fig. 8 and the cylinder 44 is operated to lower the press ram 46 from a raised position, the crimpers C1, C2 attached to the lower end of the press ram 46 respectively push the barrels 11, 12 of the crimped terminal 1 so that the barrels 11, 12 are clamped between the crimpers C1, C2 and the anvils A1, A2. When tips 11a, 12a and the other tips 11b, 12b of the barrels 11, 12 abut each other in the openings of the crimpers C1, C2 as shown in Fig. 12A, the tips 11c, 12c of barrel claws 11a, 12a of the barrels 11, 12 come into collision with the step portions D of the crimpers C1, C2. The tips 11c, 12c of the other barrel claws 11b, 12b come into collision with the vicinities of the step portions D. In this embodiment, the differences in level h between the step portions D and other caulking surfaces E, are set to values not less than the thicknesses t of the tips 11c, 12c of the barrels 11, 12. Accordingly, there is no likelihood that the tips 11c, 12c of the one barrel claws 11a, 12a project toward the round portions Rl from the other round portions R2. As shown in Fig. 12B, when the barrels 11, 12 are further pushed, the other barrel claws 11b, 12b can be securely guided on the inner peripheral sides of the barrel claws lla, 12a, in that the chamfered surfaces 11c, 12c are formed at the tips of the other barrel claws 11b, 12b. On the other hand, as shown in Fig. 12C, when the barrels 11, 12 are further pushed, the other barrel claws 11b, 12b can readily get over the step portions D, in that the chamfered surfaces 11c, 12c are formed at the tips of the barrel claws 11b, 12b, that the step portions D are inclined at an angle of 45°, and that the differences in level h are set to 1.5 times the thicknesses t of the tips of the barrel claws 11b, 12b. This securely prevents the barrels 11, 12 from being crimped to the electric wire W with the tips of the barrels 11, 12 abutting each other. In this embodiment, as best shown in Fig. 12C, virtual lines connecting the deepest points Q of the pressure receiving surfaces R3 for receiving the barrels 11, 12, to the deepest points P of the caulking surfaces E for caulking the barrels 11, 12, are opposite to and parallel with the axes of linear symmetry L2 of the barrels 11, 12. Accordingly, the crimped portions X of the barrels 11, 12 are caulked such that the portions thereof along the axes of linear symmetry L2 project most. Accordingly, as shown in Fig. 13, even though the crimped portion X of each of the barrels 11, 12 is held by the measuring device 2 shown in Fig. 6 while maintaining each of the barrels 11, 12 in a caulked posture, no moment of rotation is applied to the crimped portion X of each of the barrels 11, 12. This prevents the crimped terminal from being unexpectedly rotated. Thus, the crimp height H can be accurately measured. It is therefore possible to accurately judge whether the crimping is good or defective. In the embodiment above-mentioned, the present invention is shown as applied to both the crimper C1 for caulking the wire barrel 11 and the crimper C2 for caulking the insulation barrel 12. However, the present invention should not be limited to such an application, but may be applied to either one of the crimpers. The present invention should not be limited to the embodiment above-mentioned, which is shown as a specific example only for clarifying the technical contents of the present invention. The present invention should not be construed in a narrow sense as limited to this specific example.

Claims: The use in crimping a crimped terminal having a barrel (11, 12) whose tips (11a, 11b, 12a, 12b) are chamfered at outer peripheral sides thereof to an end of an electric wire, of a terminal crimping apparatus comprising: pressure receiving means (A1, A2) provided at a tip thereof with a pressure receiving surface (R3) for receiving the crimped terminal (1); and caulking means (C1, C2) having a caulking surface (E) adapted to receive said tip of said pressure receiving means (A1, A2), for caulking the barrel (11, 12) of the crimped terminal (1) between said caulking surface (E) and said pressure receiving surface (R3) of said pressure receiving means (A1, A2) such that one tip (11a, 12a,) of the barrel (11, 12) overlaps the other tip (11b, 12b) of the barrel; wherein said caulking means (C1, C2) has two rounding surfaces (R1, R2) smoothly integrating with each other so as to form a step portion (D) having one end located at the deepest point (P) formed at a middle portion of said caulking surface (E), and said step portion (D) has a difference (h) in level at least equal to the thickness (t) of the tips (11a, 12a) of the barrel (11, 12). The use of a terminal crimping apparatus according to claim 1, wherein said step portion (D) forms an inclined surface which is inclined from one round portion (R1) to the other round portion (R2). The use of a terminal crimping apparatus according to claim 2, wherein said inclined surface is inclined at an angle of 45° with respect to a displacing direction of said caulking means (C1, C2). The use of a terminal crimping apparatus according to any of claims 1 to 3, wherein the difference (h) in level is in the range from about 1 time to about 1.5 times of the thickness (t) of the tips (11a, 12a) of the barrel (11, 12). The use of a terminal crimping apparatus according to any of claims 1 to 4 wherein the tips (11a, 12a) of the barrel (11, 12) are chamfered such that the thickness (t) of the tips (11, 12) is a half of the entire thickness (T) of the barrel (11, 12). The use of a terminal crimping apparatus according to any of claims 1 to 5, wherein the barrel is an insulation barrel (12) to be crimped to a coated tip (W2) of an electric wire (W). The use of a terminal crimping apparatus according to claim 6, wherein said caulking means comprises a crimper (C2) for caulking the insulation barrel (12). The use of a terminal crimping apparatus according to any of claims 1 to 7, wherein the barrel is a wire barrel (11) to be crimped to the conductor (W1) of an electric wire (W). The use of a terminal crimping apparatus according to claim 8, wherein the caulking means comprises a crimper (C1) for caulking the wire barrel (11). The use of a terminal crimping apparatus according to any of claims 1 to 9, wherein a deepest point (Q) of said pressure receiving means (A1, A2) and said deepest point (P) of said caulking means (C1, C2) are located along a virtual line (L3) parallel with a symmetrical line of the barrel (11, 12). The use of a terminal crimping apparatus according to claim 10, wherein the virtual line (L3) extends along a direction in which said caulking means are stroked.

Inventors: ITO AKIRA, TAKUBO MAMORU, ITO, AKIRA, TAKUBO, MAMORU, Ito, Akira, c/o Sumitomo Wiring Systems, Ltd., Takubo, Mamoru, c/o Sumitomo Wiring Systems, Ltd.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1993
Main classification: H01R43
IPC codes: H01R43