Terminal pull force detection apparatus

Abstract

The present application relates to wire processing detection technical field, disclose a kind of terminal tension detection equipment, comprising: protective shell;Tensioning assembly, for fixed and tensioning the cable portion of terminal to be detected, and installed on the protective shell;Terminal chuck, for fixing the head of terminal to be detected;Reset component, including upper fixed plate, connecting piece, tension sensor and drive structure, the upper fixed plate is fixedly arranged in the protective shell interior, one end of the tension sensor is connected with the upper fixed plate, the other end of the tension sensor is connected with the connecting piece, the drive structure is installed on one side of the upper fixed plate, the drive structure is connected with the connecting piece, and one end of the tension sensor is connected, the terminal chuck is rotatably arranged in the connecting piece through the protective shell. The technical scheme provided in the present application can test the tension of the produced terminal, and record the maximum tension of the terminal through the sensor, thereby improving the quality inspection efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wire processing detection, and particularly relates to a terminal tension detection device. BACKGROUND

[0002] In the field of electronic connector manufacturing, accurate measurement of terminal tension is a key link to ensure connection reliability.

[0003] In the field of electronic connector manufacturing, as a core conductive component, the tensile strength of the terminal after crimping with the wire directly determines the connection reliability. If the terminal tension does not meet the design index, it is easy to break under the subsequent assembly, vibration or external pulling environment, resulting in interruption of device signal transmission, short circuit and even safety accidents, becoming one of the main quality hidden troubles of electronic system failure.

[0004] At present, most manufacturers in the market rely on general material testing machines for testing. Such devices need to record the peak tension manually, which is time-consuming and laborious, and it is difficult to meet the quality control needs of terminals on the production line.

[0005] Therefore, it is urgent to provide a detection device for measuring terminal tension to solve the above problems. SUMMARY

[0006] The main purpose of the present application is to provide a terminal tension detection device, which aims to automatically test the tension of the produced terminal.

[0007] To achieve the above purpose, the present application provides a terminal tension detection device, which comprises: a protective shell; a tensioning assembly for fixing and tensioning the cable part of the terminal to be detected, and installed on the protective shell; a terminal chuck for fixing the head part of the terminal to be detected; a reset assembly comprising an upper fixed plate, a connecting piece, a tension sensor and a driving structure, the upper fixed plate is fixedly arranged inside the protective shell, one end of the tension sensor is connected with the upper fixed plate, the other end of the tension sensor is connected with the connecting piece, the driving structure is installed on one side of the upper fixed plate, the driving structure is connected with the end of the connecting piece away from the tension sensor, and the terminal chuck is rotatably arranged on the connecting piece through the protective shell; in use, the cable part is tensioned to make the tension acting on the terminal to be detected transmitted from the terminal chuck to the tension sensor through the connecting piece to collect tension data, and after the collection is completed, the driving structure drives the terminal chuck to move back to the original position.

[0008] Preferably, the driving structure comprises a driving motor, a reduction box and a ejector rod head, the reduction box is installed on the upper fixed plate, the driving motor is in transmission connection with the input end of the reduction box, the output end of the reduction box is in transmission connection with the ejector rod head, the ejector rod head is connected with the connecting piece, and the ejector rod head drives the terminal chuck on the connecting piece to move up and down under the driving of the driving motor.

[0009] Preferably, the reset assembly further comprises a moving plate and a lower fixed plate, the lower fixed plate is fixedly arranged in the protective shell and located below the upper fixed plate, the moving plate is connected with the ejector rod head, and a straight light axis penetrating through the moving plate is connected between the upper fixed plate and the lower fixed plate, and a limit bearing is arranged between the straight light axis and the moving plate.

[0010] Preferably, a trigger baffle is arranged on the side of the moving plate facing the connecting piece, a first photoelectric switch is arranged at the bottom end of the connecting piece and corresponds to the trigger baffle, the lower fixed plate is provided with a second photoelectric switch corresponding to the trigger baffle, and the first photoelectric switch and the second photoelectric switch are used to send signals to the driving motor to prevent the moving plate from being out of position when the moving plate moves to the upper and lower limits.

[0011] Preferably, the terminal shape detection assembly further comprises a micrometer, an upper positioning column and a lower positioning column, the micrometer is arranged on one side of the protective shell, the upper positioning column is connected to the micrometer and can move in the axial direction of the rod of the micrometer, the lower positioning column is correspondingly arranged at the bottom end of the upper positioning column, and the terminal to be detected is pressed between the upper positioning column and the lower positioning column.

[0012] Preferably, the tensioning assembly comprises an eccentric pull wheel and a driven clamping wheel, the eccentric pull wheel is arranged on the protective shell, the driven clamping wheel is arranged on one side of the eccentric pull wheel and engages with the eccentric pull wheel, and the engagement surfaces of the eccentric pull wheel and the driven clamping wheel are respectively provided with surface textures for enhancing the engagement force.

[0013] Preferably, the tensioning assembly further comprises a mounting plate, a first transmission gear and a second transmission gear, the mounting plate is arranged on the protective shell, the first transmission gear and the second transmission gear are respectively arranged on the side of the mounting plate away from the terminal chuck, the first transmission gear is in meshing connection with the second transmission gear, the mounting plate is provided with a pair of arc-shaped rotating grooves, the eccentric pull wheel passes through the arc-shaped rotating grooves and is connected with the first transmission gear, and the driven clamping wheel passes through the arc-shaped rotating grooves and is connected with the second transmission gear.

[0014] Preferably, the data processing module arranged inside the protective shell is further provided, the display screen is arranged above the protective shell, the data processing module is electrically connected with the display screen, the tension sensor and the micrometer respectively, and the display screen is used for displaying the terminal tension and the terminal shape data collected after being processed by the data processing module.

[0015] Preferably, the protective shell is provided with a wire sleeve, and the wire sleeve is arranged on one side of the terminal shape detection assembly.

[0016] Preferably, a plurality of clamping grooves suitable for terminals with different diameters to be tested are arranged on the periphery of the terminal chuck.

[0017] In the technical scheme, the driving structure actively pulls the connecting piece after each test, so that the terminal chuck automatically and accurately returns to the initial zero position, thereby cutting off the possibility of cumulative errors of the terminal chuck position drift from the source. The driving structure can select different linear motion modules according to the accuracy of the reset, such as servo, stepping motor or even cylinder power components. The rigid straight connection structure between the tension sensor, the connecting piece and the terminal chuck, in combination with the dynamic calibration of the reset action of the driving structure, ensures that the stress axis of each test completely coincides with the predetermined stress axis, accurately feeds back the dynamic tension value at the moment of terminal rupture, and does not cause distortion of the terminal rupture data due to large changes in the stress axis direction of the sensor, so that the terminal after production can be tested with high precision, and the production efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are schematic and not intended to be limiting of the embodiments, and in which like reference numerals refer to like elements in the various figures of the drawings in which: the figures are not to scale.

[0019] Figure 1 FIG. 1 is a schematic diagram of the overall structure of an embodiment of the terminal tension detection device of the present application;

[0020] Figure 2 FIG. 2 is a schematic diagram of the front view structure of an embodiment of the terminal tension detection device of the present application;

[0021] Figure 3 FIG. 3 is a schematic diagram of the side view structure of an embodiment of the terminal tension detection device of the present application;

[0022] Figure 4 FIG. 4 is a schematic diagram of the top view structure of an embodiment of the terminal tension detection device of the present application;

[0023] Figure 5 FIG. 5 is a sectional view at A-A in FIG. 1; Figure 4 ​

[0024] Figure 6 Figure 1 is a schematic diagram of the overall structure of the reset assembly in the present application;

[0025] Figure 7 Figure 1 is a schematic diagram of the overall structure of the reset assembly in the present application;

[0026] Figure 1 is a schematic diagram of the overall structure of the reset assembly in the present application;

[0027] 1, protective shell; 11, display screen; 12, wire cover;

[0028] 2, tension assembly; 21, eccentric tension pulley; 22, driven clamping pulley; 23, mounting plate; 231, arc-shaped rotating groove; 24, first transmission gear; 25, second transmission gear;

[0029] 3, terminal chuck; 31, clamping groove;

[0030] 4, reset assembly; 41, upper fixed plate; 42, connecting piece; 43, tension sensor; 44, driving structure; 441, driving motor; 442, speed reducer; 443, top rod head; 444, plug; 45, moving plate; 451, straight optical axis; 452, limit bearing; 46, lower fixed plate; 47, first photoelectric switch; 471, trigger baffle; 48, second photoelectric switch;

[0031] 5, terminal shape detection assembly; 51, micrometer; 52, upper positioning column; 53, lower positioning column. DETAILED DESCRIPTION

[0032] In order to facilitate the understanding of the present application, the present application will be described in more detail below in conjunction with the drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or one or more intervening elements can be present therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element, or one or more intervening elements can be present therebetween. The terms "vertical", "horizontal", "left", "right", "inner", "outer" and similar expressions used in the present specification are for illustrative purposes only. In the description of the present application, the terms "first", "second" are used only for descriptive purposes and cannot be understood as indicating relative importance or implying the number of the indicated technical features. Thus, unless otherwise specified, the features defined with "first", "second" can explicitly or implicitly include one or more of the features; the meaning of "multiple" is two or more. The term "comprise" and any variation thereof means non-exclusive inclusion, and one or more other features, integers, steps, operations, units, components and / or combinations thereof can be present or added.

[0033] Furthermore, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through intermediate medium, or internal connection of two elements. All technical and scientific terms used in the specification are the same as the meanings commonly understood by the skilled in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used in the specification includes any and all combinations of one or more related listed items.

[0034] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as there is no conflict.

[0035] Please refer to Figures 1 to 7 The application provides a terminal tension detection device, which comprises a protective shell 1, a tension assembly 2, which is used for fixing and tensioning a cable part of a terminal to be detected and is installed on the protective shell 1, a terminal chuck 3, which is used for fixing a head part of the terminal to be detected, and a reset assembly 4, which comprises an upper fixed plate 41, a connecting piece 42, a tension sensor 43 and a driving structure 44, the upper fixed plate 41 is fixedly arranged in the protective shell 1, one end of the tension sensor 43 is connected with the upper fixed plate 41, the other end of the tension sensor 43 is connected with the connecting piece 42, the driving structure 44 is installed on one side of the upper fixed plate 41, the driving structure 44 is connected with one end of the connecting piece 42, which is away from the tension sensor 43, and the terminal chuck 3 is rotatably arranged in the connecting piece 42 and penetrates through the protective shell 1. When in use, the tension cable part is used to make the tension acting on the terminal to be detected pass through the connecting piece 42 from the terminal chuck 3 to the tension sensor 43 to collect tension data, and after the collection is completed, the driving structure 44 drives the terminal chuck 3 to move and reset.

[0036] In the technical solution, the head of the terminal to be detected is clamped in the terminal chuck 3, the cable part of the terminal to be detected is fixed in the tensioning assembly 2, the tensioning assembly 2 is used to straighten the terminal to be detected until it is broken, the instantaneous maximum bearing tension transmitted from the terminal chuck 3 to the connecting piece 42 can be directly sensed by the tension sensor 43, and the test tension data is stored in the internal storage medium or the external database. After the test, the internal driving structure 44 drives the terminal chuck 3 to reset through the connecting piece 42 to wait for the next terminal to be detected. The driving structure 44 actively pulls the connecting piece 42 after each test, so that the terminal chuck 3 accurately returns to the initial zero position, thereby cutting off the possibility of position drift of the terminal chuck 3. The driving structure 44 can select different linear motion modules according to the resetting accuracy, such as servo, stepping motor or even cylinder power components. The rigid straight connection structure between the tension sensor 43, the connecting piece 42 and the terminal chuck 3, in combination with the dynamic calibration of the resetting action of the driving structure 44, ensures that the stress axis of each test is completely coincided with the predetermined stress axis, so that the dynamic tension value at the moment of terminal breakage can be accurately fed back, and the problem of distortion of terminal breakage data caused by large change in the direction of the stress axis of the sensor can be avoided.

[0037] Please refer to Figures 1 to 7 In the embodiment, the driving structure 44 includes a driving motor 441, a reduction box 442 and a top rod head 443. The reduction box 442 is installed on the upper fixed plate 41, the driving motor 441 is in transmission connection with the input end of the reduction box 442, the output end of the reduction box 442 is in transmission connection with the top rod head 443, the top rod head 443 is connected with the connecting piece 42, and the top rod head 443 drives the terminal chuck 3 on the connecting piece 42 to move up and down under the driving of the driving motor 441. A plug 444 is arranged between the reduction box 442 and the top rod head 443, so as to convert the rotary torque output by the reduction box 442 into the pure axial thrust required by the top rod head 443. In the whole driving structure 44, the reduction box 442 can reduce the rotary torque and the reverse rotary torque directly acting on the top rod head 443 by the driving motor 441, and the top rod head 443 only transmits the axial thrust, so as to ensure that the tension sensor 43 is isolated from the torsional stress interference, and prevent the connecting piece 42 from being excessively shaken to affect the resetting accuracy of the connecting piece 42 and the terminal chuck 3.

[0038] Please refer to Figures 1 to 7In the embodiment, the reset assembly 4 further comprises a moving plate 45 and a lower fixed plate 46, the lower fixed plate 46 is fixedly arranged in the protective shell 1 below the upper fixed plate 41, the moving plate 45 is connected with the top rod head 443, and a straight light axis 451 penetrating through the moving plate 45 is connected between the upper fixed plate 41 and the lower fixed plate 46, and a limit bearing 452 is arranged between the straight light axis 451 and the moving plate 45. Wherein, at least two straight light axes 451 are arranged, and the cooperation between the moving plate 45 and the straight light axis 451 is mainly to prevent the entire reset assembly 4 from being laterally deviated to affect the stress path of the tension sensor 43 during multiple back-and-forth resetting, and to reduce the horizontal deviation of the terminal chuck 3.

[0039] Please refer to Figures 1 to 7 In the embodiment, one side of the moving plate 45 facing the connecting piece 42 is provided with a trigger baffle 471, the first photoelectric switch 47 is arranged at the bottom end of the connecting piece 42 corresponding to the trigger baffle 471, the lower fixed plate 46 is provided with the second photoelectric switch 48 corresponding to the trigger baffle 471, and the first photoelectric switch 47 and the second photoelectric switch 48 are used to send signals to the driving motor 441 when the moving plate 45 moves to the upper and lower limits to prevent the moving plate 45 from being out of position. Through the arrangement of the photoelectric switch and the trigger baffle 471, the out-of-position of the entire reset assembly 4 during the up-and-down movement can be effectively prevented, and the vertical deviation of the terminal chuck 3 can be reduced.

[0040] Please refer to Figures 1 to 7 In the embodiment, the device further comprises a terminal shape detection assembly 5, the terminal shape detection assembly 5 comprises a micrometer 51, an upper positioning column 52 and a lower positioning column 53, the micrometer 51 is arranged on one side of the protective shell 1, the upper positioning column 52 is connected to the micrometer 51 and can move in the axial direction of the rod of the micrometer 51, the lower positioning column 53 is arranged at the bottom end of the upper positioning column 52, and the terminal to be detected is pressed between the upper positioning column 52 and the lower positioning column 53. When in use, the upper positioning column 52 is lifted to place the terminal to be detected on the lower positioning column 53, and then the upper positioning column 52 is lowered to abut on the terminal to be detected, the terminal can be measured multiple times by this method to obtain the basic shape dimensions such as the width and height of the terminal, and the terminal to be detected can be quickly transferred to the tension assembly 2 for destructive tension test, and the basic shape dimensions measured can be recorded in the internal or external storage medium through the built-in circuit of the micrometer 51 to complete the digital full-process tracking.

[0041] Please refer to Figures 1 to 7In the embodiment, the tensioning assembly 2 comprises an eccentric tensioning wheel 21 arranged on the protective shell 1 and a driven clamping wheel 22 arranged on one side of the eccentric tensioning wheel 21 and engaged with the eccentric tensioning wheel 21, and the engagement surfaces of the eccentric tensioning wheel 21 and the driven clamping wheel 22 are respectively provided with surface textures for enhancing the engagement force. The tensioning assembly 2 further comprises a mounting plate 23 arranged on the protective shell 1, a first transmission gear 24 and a second transmission gear 25 respectively mounted on the side of the mounting plate 23 away from the terminal chuck 3, the first transmission gear 24 is engaged with the second transmission gear 25, and the mounting plate 23 is provided with a pair of arc-shaped rotating grooves 231, the eccentric tensioning wheel 21 is connected with the first transmission gear 24 through the arc-shaped rotating grooves 231, and the driven clamping wheel 22 is connected with the second transmission gear 25 through the arc-shaped rotating grooves 231. In use, the terminal cable part to be detected is placed on the surface textures near the engagement position of the eccentric tensioning wheel 21 and the driven clamping wheel 22, and the handle of the eccentric tensioning wheel 21 is held to rotate, so that the eccentric tensioning wheel 21 drives the driven clamping wheel 22 to rotate through the first transmission gear 24 and the second transmission gear 25 to grasp and straighten the terminal to be detected. The arc-shaped rotating grooves 231 limit the upper and lower limits of the rotation of the driving tensioning wheel, and the first transmission gear 24 and the second transmission gear 25 are used to prevent the handle from impacting other components and to prevent the terminal to be detected from falling off or being excessively tensioned in the assembly.

[0042] In the embodiment, the data processing module arranged in the protective shell 1, the display screen 11 arranged above the protective shell 1, the data processing module is electrically connected with the display screen 11, the tension sensor 43 and the micrometer 51, and the display screen 11 is used to display the terminal tension and terminal shape data collected after being processed by the data processing module. The data processing module can analyze the average tension and instantaneous maximum tension collected by the tension sensor 43, generate the same terminal tension bearing curve, and comprehensively analyze the quality of the current batch of terminals in combination with the width and height of the corresponding terminal joint section. In order to facilitate the observation of the staff, all the data collected by the data processing module and the analysis can be displayed through the display screen 11.

[0043] Please refer to Figures 1 to 7 In the embodiment, the protective shell 1 is provided with a wire protection sleeve 12 located on one side of the terminal shape detection assembly 5, and the wire protection sleeve 12 is mainly used for protecting the terminal cable. The terminal chuck 3 is provided with a plurality of clamping grooves 31 suitable for terminals to be tested with different diameters, and the clamping grooves 31 are suitable for terminal cables with different width specifications and mainly in U-shaped, and can also be in V-shaped to facilitate clamping and prevent the terminal chuck 3 from falling off in the process of straightening the terminal.

[0044] The above examples are only used to illustrate the technical solutions of the present application, but not to limit the present application; the technical features in the above examples or different examples can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in details for simplicity; although the present application has been described in detail with reference to the foregoing examples, it should be understood by those of ordinary skill in the art that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A terminal tension detection apparatus characterized by comprising: The utility model relates to a kind of terminal tension testing device, including: Protective shell (1); Tensioning assembly (2), for fixing and tensioning the cable part of terminal to be detected, and install on the protective shell (1); Terminal chuck (3), for fixing the head of terminal to be detected; Reset assembly (4), including upper fixed plate (41), connecting piece (42), tension sensor (43) and drive structure (44), the upper fixed plate (41) is fixedly arranged in the protective shell (1) interior, one end of the tension sensor (43) is connected with the upper fixed plate (41), the other end of the tension sensor (43) is connected with the connecting piece (42), the drive structure (44) is installed on one side of the upper fixed plate (41), the drive structure (44) is connected with the one end of the connecting piece (42) away from the tension sensor (43), the terminal chuck (3) is rotatably arranged in the connecting piece (42) by the protective shell (1); When using, tension the cable part makes the tension acting on the terminal to be detected be transmitted from the terminal chuck (3) to the tension sensor (43) and collect tension data, after collection, the drive structure (44) drives the terminal chuck (3) and moves reset; The drive structure (44) includes drive motor (441), speed reducer (442) and top rod head (443), the speed reducer (442) is installed on the upper fixed plate (41), the drive motor (441) is drivingly connected with the input end of the speed reducer (442), the output end of the speed reducer (442) is drivingly connected with the top rod head (443), the top rod head (443) is connected with the connecting piece (42), the top rod head (443) is driven by the drive motor (441) and drives the terminal chuck (3) on the connecting piece (42) to move up and down and reset.

2. The terminal tension detecting apparatus according to claim 1, characterized by The reset assembly (4) further includes moving plate (45) and lower fixed plate (46), the lower fixed plate (46) is fixedly arranged in the protective shell (1) and is located below the upper fixed plate (41), the moving plate (45) is connected with the top rod head (443), a straight light axis (451) is connected between the upper fixed plate (41) and the lower fixed plate (46) and penetrates the moving plate (45), and a limit bearing (452) is arranged between the straight light axis (451) and the moving plate (45).

3. The terminal pull strength testing apparatus of claim 2, wherein The side of the moving plate (45) towards the connecting piece (42) is provided with a trigger baffle (471), a first photoelectric switch (47) is installed at the bottom end of the connecting piece (42) corresponding to the trigger baffle (471), the lower fixed plate (46) is provided with a second photoelectric switch (48) corresponding to the trigger baffle (471), and the first photoelectric switch (47) and the second photoelectric switch (48) are used to send signals to the drive motor (441) to prevent the moving plate (45) from being out of position when the moving plate (45) moves to the first photoelectric switch (47) trigger limit or the second photoelectric switch (48) trigger limit.

4. The terminal tension detecting apparatus according to any one of claims 1 to 3, characterized by The terminal shape detection assembly (5) comprises a micrometer (51), an upper positioning column (52) and a lower positioning column (53), the micrometer (51) is arranged on one side of the protective shell (1), the upper positioning column (52) is connected to the micrometer (51) and can move in the axial direction of the rod of the micrometer (51), and the lower positioning column (53) is correspondingly arranged at the bottom end of the upper positioning column (52), and the terminal to be detected is pressed between the upper positioning column (52) and the lower positioning column (53).

5. The terminal pull strength testing apparatus of claim 4, wherein The tensioning assembly (2) comprises an eccentric pull wheel (21) and a driven clamping wheel (22), the eccentric pull wheel (21) is arranged on the protective shell (1), the driven clamping wheel (22) is arranged on one side of the eccentric pull wheel (21) and engages with the eccentric pull wheel (21), and the engagement surfaces of the eccentric pull wheel (21) and the driven clamping wheel (22) are respectively provided with surface textures for enhancing the engagement force.

6. The terminal pull strength testing apparatus of claim 5, wherein The tensioning assembly (2) further comprises a mounting plate (23), a first transmission gear (24) and a second transmission gear (25), the mounting plate (23) is arranged on the protective shell (1), the first transmission gear (24) and the second transmission gear (25) are respectively arranged on the side of the mounting plate (23) away from the terminal chuck (3), the first transmission gear (24) engages with the second transmission gear (25), the mounting plate (23) is provided with a pair of arc-shaped rotating grooves (231), the eccentric pull wheel (21) passes through the arc-shaped rotating grooves (231) and is connected with the first transmission gear (24), and the driven clamping wheel (22) passes through the arc-shaped rotating grooves (231) and is connected with the second transmission gear (25).

7. The terminal pull strength testing apparatus of claim 6, wherein A data processing module is arranged in the protective shell (1), a display screen (11) is arranged above the protective shell (1), the data processing module is electrically connected with the display screen (11), the tension sensor (43) and the micrometer (51), and the display screen (11) is used for displaying the terminal tension and terminal shape data processed by the data processing module.

8. The terminal pull strength testing apparatus of claim 7, wherein The protective shell (1) is provided with a wire protection sleeve (12), and the wire protection sleeve (12) is located on one side of the terminal shape detection assembly (5).

9. The terminal pull strength testing apparatus of claim 8, wherein A plurality of clamping grooves (31) suitable for terminals with different diameters are arranged on the periphery of the terminal chuck (3).

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