Negative electrode welding machine for assembling large cylindrical battery

Abstract

The invention relates to the technical field of laser welding processing, in particular to a negative electrode welding machine for assembling a large cylindrical battery, which is mainly characterized in that on one hand, an adaptive cylindrical battery fastening and positioning assembly is arranged in a supporting barrel to provide a positioning function; the welding processing flexibility is improved; furthermore, a corresponding protection auxiliary assembly is arranged in the supporting barrel, so that an anode head at the bottom end of the cylindrical battery is protected by the protection auxiliary assembly when a negative electrode at one end of the cylindrical battery is welded, and the anode head is prevented from being damaged in the machining and positioning process; the protection auxiliary assembly also has a horizontal correction effect on the cylindrical battery; the negative electrode welding processing quality is ensured; and the welding clamping assembly is further connected with the welding auxiliary assembly, the smoke generated in the welding machining process can be absorbed, and pollution to the working environment and influence on work of workers are avoided as much as possible.

Description

Technical Field

[0001] The invention relates to the technical field of laser welding processing, in particular to a negative electrode welding machine for assembling large cylindrical batteries. Background Art

[0002] The existing document with announcement number CN116160112A discloses a laser welding and assembly production line for manufacturing large cylindrical lithium batteries, and its scheme includes a sorting box, a double-speed line body, a detection box, an operation box, a first welding box, a flipping mechanism, a second welding box, a material unloading and transfer box and an assembly line body; the initial end of the double-speed line body is connected to the end of the sorting box, and the double-speed line body passes through the detection box, the operation box, the first welding box, the flipping mechanism and the second welding box in sequence, and the end of the double-speed line body is connected to the initial end of the material unloading and transfer box; the end of the material unloading and transfer box is connected to the initial end of the assembly line body; to solve the problem that as the demand for large cylindrical battery modules is gradually increasing, the production efficiency of large cylindrical battery modules also needs to be gradually improved, but the existing production equipment cannot meet the needs of automated production of detection, sorting, assembly and spot welding of large cylindrical batteries.

[0003] The existing large cylindrical battery negative electrode welding process is generally carried out by corresponding welding machines, which have high welding work efficiency in mass production. For small batches or products that are missed or welded unqualified on the welding production line, workers generally use corresponding cylindrical battery laser welding devices for processing. First, the cylindrical battery is vertically fixed on the corresponding fixed tooling, and then the welding process is carried out by the welding mechanism. In this process, when the negative end of the cylindrical battery is welded, its anode head is at the bottom, and the existing welding fixed tooling lacks a suitable protection function for its anode head, which can easily cause collision damage to the anode head position. Furthermore, when performing vertical positioning, after the cylindrical battery is clamped, it cannot be confirmed whether its negative end surface is in a horizontal position, which has a certain impact on the subsequent welding process quality. The smoke generated during the welding process will also affect the workers. Therefore, the existing battery welding processing device lacks a suitable auxiliary mechanism to meet its welding processing needs.

[0004] To this end, the present invention proposes a negative electrode welding machine for large cylindrical battery assembly to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a negative electrode welding machine for large cylindrical battery assembly to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solutions: a negative electrode welding machine for large cylindrical battery assembly, comprising a welding machine workbench, a welding mechanism, a protective auxiliary component and a welding clamping component; The welding machine workbench is provided with a welding mechanism, and the welding mechanism is connected with a welding head; The welding machine workbench is provided with a protective auxiliary component and a welding clamping component; The welding clamping assembly is arranged in the supporting cylinder, a fixing plate is fixedly arranged at the bottom end of the supporting cylinder, and the fixing plate is fixedly arranged on the welding machine workbench by screws; The welding clamping assembly clamps and fixes the cylindrical battery.

[0007] Preferably, the protective auxiliary component includes a limiting cylinder, a connecting ring body, an installation slot, a movable column, a protective groove, an auxiliary spring, and an installation plate; a connecting ring body is fixedly provided at the bottom end of the limiting cylinder, and the connecting ring body is fixed on the welding machine workbench by screws, and an installation slot is provided at the bottom end of the connecting ring body, and a threaded groove is provided in the installation slot, and the movable column is movably provided in the limiting cylinder.

[0008] Preferably, the connecting ring body is arranged in the supporting cylinder, and the center lines of the two are on the same straight line.

[0009] Preferably, a protective groove is provided at the top end of the movable column, an auxiliary spring is fixedly provided at the bottom end of the movable column, the bottom end of the auxiliary spring is fixedly provided on a mounting card plate, the mounting card plate is adapted to be clamped in the mounting slot, and the mounting card plate is fixed by screws.

[0010] Preferably, the welding clamping assembly includes a clamping body, a rubber auxiliary strip, a movable insert strip, a connecting screw groove, a transmission column, a driving groove body, an internal thread regulating disk and an auxiliary handle; the movable insert strip is equidistantly and movably inserted in the supporting cylinder body, one end of the movable insert strip extends to the inside of the supporting cylinder body, and the clamping body is fixedly arranged on the end, the other end of the movable insert strip extends to the outside of the supporting cylinder body, and the transmission column is fixedly arranged on the end, one end of the rubber auxiliary strip extends into the driving groove body, and a connecting screw groove is arranged on one side of the top of the clamping body.

[0011] Preferably, the inner side wall of the movable insert is arranged as an arc surface, and rubber auxiliary strips are fixedly arranged at equal intervals on the arc surface.

[0012] Preferably, the driving grooves are equidistantly arranged at the bottom end of the internal thread regulating disk, the internal thread regulating disk is threadedly connected to the outer wall of the supporting cylinder, and auxiliary handles are equidistantly fixed at the top end of the internal thread regulating disk.

[0013] Preferably, the number of groups of the driving slots and the transmission columns is the same, and the driving slots are arranged in an arc shape.

[0014] Preferably, the connecting screw groove is connected to the welding auxiliary component, and the welding auxiliary component includes a connecting box body, a connecting plate, an air suction connecting pipe, a loading tank body, a first magnetic block, a loading frame, an auxiliary clip, a handle, a second magnetic block, an absorption hole, a conical tube head, an auxiliary cotton plate and a sleeve hole; a connecting plate is fixedly provided at the bottom end of the connecting box body, a mounting hole is provided on the connecting plate, and a mounting screw passes through the mounting hole and is threadedly connected to the connecting screw groove on the clamping body, an air suction connecting pipe is provided on one side of the connecting box body, a loading tank body is provided at the box mouth position of the connecting box body, a first magnetic block is embedded in the loading tank body, auxiliary clips are symmetrically fixedly provided at both ends of the loading frame, a handle is provided on the auxiliary clip, and a second magnetic block is embedded on one side of the auxiliary clip.

[0015] Preferably, absorption holes are equidistantly arranged in the loading frame, and a conical tube head is fixedly arranged on one side of the absorption hole, the large port of the conical tube head is connected to the orifice of the absorption hole, and the auxiliary cotton board is equidistantly arranged with sleeve holes, the auxiliary cotton board is placed in the loading frame, the sleeve holes correspond to the setting positions of the conical tube head, the setting groups are the same, and the aperture of the sleeve holes is larger than the small port diameter of the conical tube head, and smaller than the large port diameter of the conical tube head.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The negative electrode welding machine for large cylindrical battery assembly designed by the present invention mainly has the following features: on the one hand, a matching cylindrical battery fastening and positioning assembly is arranged in the supporting cylinder to provide a positioning function; and its welding processing flexibility is improved; and further, by arranging a corresponding protective auxiliary assembly in the supporting cylinder, when the negative electrode at one end of the cylindrical battery is welded, the anode head at the bottom end of the cylindrical battery is protected by the protective auxiliary assembly, so as to avoid damage to the anode head during the processing and positioning process, thereby ensuring the quality of the product body, and on this basis, the protective auxiliary assembly also has a horizontal correction effect on the cylindrical battery, thereby ensuring the quality of its negative electrode welding process; a welding auxiliary assembly is also connected to the arranged welding clamping assembly, wherein the arranged connecting box body, the suction connecting pipe and the loading frame are used in coordination, so as to absorb the fume generated during the welding process, thereby minimizing pollution to the working environment and affecting the work of the staff; the present invention provides an auxiliary mechanism matched with the battery welding processing device to meet its welding processing requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structural connection of the large cylindrical battery welding device of the present invention; Figure 2 For the present invention Figure 1 A magnified schematic diagram of the structural connection at center A; Figure 3It is a top view of the structural connection of the protection auxiliary component and the welding clamping component of the present invention; Figure 4 For the present invention Figure 3 A magnified schematic diagram of the structural connection at B in the middle; Figure 5 For the present invention Figure 3 A magnified schematic diagram of the structural connection at C in the middle; Figure 6 This is a bottom view of the structural connection of the protection auxiliary component and the welding clamping component of the present invention; Figure 7 For the present invention Figure 6 The enlarged schematic diagram of the structural connection at D in the middle; Figure 8 For the present invention Figure 6 The enlarged schematic diagram of the structural connection at E in the middle; Fig. 9 It is a schematic diagram of the right side of the explosion of the welding auxiliary component structure connection of the present invention; Fig.10 For the present invention Fig. 9 The enlarged schematic diagram of the structural connection at F in the middle; Fig.11 It is a schematic diagram of the left side of the explosion of the welding auxiliary component structure connection of the present invention; Fig.12 For the present invention Fig.11 Enlarged schematic diagram of the structural connection at G in the middle.

[0018] In the figure: welding machine workbench 1, welding mechanism 2, welding head 21, cylindrical battery 3, supporting cylinder 4, fixing plate 41, limiting cylinder 501, connecting ring body 502, mounting card slot 503, movable column 504, protective groove 505, auxiliary spring 506, mounting card plate 507, clamping body 601, rubber auxiliary strip 602, movable insert strip 603, connecting screw slot 604, transmission column 605, driving slot body 606, internal thread regulating disk 607, auxiliary handle 608, connecting box body 701, connecting plate 702, suction connecting pipe 703, loading slot body 704, first magnetic block 705, loading frame body 706, auxiliary card strip 707, handle 708, second magnetic block 709, absorption hole 710, cone pipe head 711, auxiliary cotton board 712, sleeve hole 713. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. The embodiments of the present invention and all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0020] Example 1: Please refer to Figure 1-Figure 12A negative electrode welding machine for assembling large cylindrical batteries, comprising a welding machine workbench 1, a welding mechanism 2, a protective auxiliary component and a welding clamping component; wherein a welding mechanism 2 is arranged on the welding machine workbench 1, and a welding head 21 is connected to the welding mechanism 2; a protective auxiliary component and a welding clamping component are arranged on the welding machine workbench 1; the welding clamping component clamps and fixes the cylindrical battery 3, and the cylindrical battery 3 is clamped and fixed by the arranged welding clamping component. At the same time, the arranged protective auxiliary component has a protective effect on the bottom end anode head of the cylindrical battery 3, so as to avoid extrusion damage to the anode head during the negative electrode welding process; after the cylindrical battery 3 is clamped and positioned, the cylindrical battery 3 is welded by the welding head 21.

[0021] The welding clamping assembly here is arranged in the supporting cylinder 4, and a fixing plate 41 is fixedly arranged at the bottom end of the supporting cylinder 4, and the fixing plate 41 is fixedly arranged on the welding machine workbench 1 by screws; wherein the welding clamping assembly in the supporting cylinder 4 can be adapted and fastened to cylindrical batteries 3 of different models, and the welding processing flexibility is high.

[0022] The present invention mainly provides a positioning function by arranging a matching cylindrical battery 3 fixing positioning component in the supporting cylinder 4, thereby improving the flexibility of welding processing; and further, by arranging a corresponding protective auxiliary component in the supporting cylinder 4, when the negative electrode at one end of the cylindrical battery 3 is welded, the anode head at the bottom end of the cylindrical battery 3 is protected by the protective auxiliary component, thereby avoiding damage to the anode head during the processing and positioning process, thereby ensuring the quality of the product itself.

[0023] Example 2: Based on Example 1, please refer to Figure 2-Figure 8 , the protective auxiliary components here include a limiting cylinder 501, a connecting ring body 502, a mounting slot 503, a movable column 504, a protective groove 505, an auxiliary spring 506, and a mounting card plate 507; a connecting ring body 502 is fixedly arranged at the bottom end of the limiting cylinder 501, and the connecting ring body 502 is fixedly arranged on the welding machine workbench 1 by screws, and a mounting slot 503 is arranged at the bottom end of the connecting ring body 502, and a threaded groove is arranged in the mounting slot 503, and the movable column 504 is movably arranged in the limiting cylinder 501; the connecting ring body 502 here is arranged in the supporting cylinder 4, and the center lines of the two are on the same straight line; a protective groove 505 is arranged at the top of the movable column 504, and an auxiliary spring 506 is fixedly arranged at the bottom end of the movable column 504, and the bottom end of the auxiliary spring 506 is fixedly arranged on the mounting card plate 507, and the mounting card plate 507 is adapted to be clamped in the mounting slot 503, and the mounting card plate 507 is fixed by screws.

[0024] Here, when the cylindrical battery 3 is clamped and positioned, when the cylindrical battery 3 is placed in the supporting cylinder 4, the bottom end of the cylindrical battery 3 contacts the movable column 504, and the anode head at the bottom end of the cylindrical battery 3 enters the protective groove 505, which will not cause squeezing, and the cylindrical battery 3 can be pressed down to adjust the position. In this process, the movable column 504 will be retracted into the limiting cylinder 501. The movable column 504 here supports the bottom end of the cylindrical battery 3, and also makes the bottom end of the cylindrical battery 3 in a horizontal state, and then it can be clamped and positioned by welding the clamping assembly.

[0025] The welding clamping assembly here includes a clamping body 601, a rubber auxiliary strip 602, a movable insert 603, a connecting screw groove 604, a transmission column 605, a driving groove 606, an internal thread regulating disk 607 and an auxiliary handle 608; the movable insert 603 is equidistantly and movably inserted in the support cylinder 4, one end of the movable insert 603 extends to the inside of the support cylinder 4, and the clamping body 601 is fixedly arranged at the end, and the other end of the movable insert 603 extends to the outside of the support cylinder 4, and the transmission column is fixedly arranged at the end Body 605, one end of the rubber auxiliary strip 602 extends into the driving slot body 606, and a connecting screw groove 604 is provided on one side of the top of the clamping body 601; the driving slot body 606 here is equidistantly arranged at the bottom end of the internal thread regulating disk 607, the internal thread regulating disk 607 is threadedly connected to the outer wall of the supporting cylinder 4, and an auxiliary handle 608 is equidistantly fixed at the top of the internal thread regulating disk 607; the driving slot body 606 here is arranged in the same number of groups as the transmission column 605, and the driving slot body 606 is arranged in an arc shape.

[0026] After the position of the cylindrical battery 3 is adjusted, the internal thread regulating disk 607 is rotated through the auxiliary handle 608, and the internal thread regulating disk 607 drives the driving groove body 606 at its bottom to squeeze and drive the transmission cylinder 605, thereby driving the movable insertion bar 603 to move, so that the clamping body 601 squeezes the side wall of the cylindrical battery 3, wherein the inner side wall of the movable insertion bar 603 is set as an arc surface, and rubber auxiliary strips 602 are fixedly arranged at equal intervals on the arc surface, which not only stabilizes the clamping positioning, but also has a protective effect on the side wall of the cylindrical battery 3 to avoid squeezing damage to the side wall of the cylindrical battery 3 due to excessive clamping force; after the positioning work is completed, the welding process can be carried out through the welding mechanism 2.

[0027] The protective auxiliary component provided in the support cylinder 4 here can also serve as a convenient material removal after welding is completed. That is, after welding is completed, by rotating the internal thread regulating disk 607 in the reverse direction, the internal thread regulating disk 607 drives the clamping body 601 to move and release the contact with the cylindrical battery 3. At the same time, the cylindrical battery 3 is pushed up by the movable column 504 and the auxiliary spring 506, so that the operator can remove it easily.

[0028] Example 3: Based on Example 2, please refer to Figure 9-12 , the connecting screw groove 604 here is connected with the welding auxiliary component, and the welding auxiliary component includes a connecting box body 701, a connecting plate 702, an air suction connecting pipe 703, a loading tank body 704, a first magnetic block 705, a loading frame body 706, an auxiliary card strip 707, a handle 708, a second magnetic block 709, an absorption hole 710, a cone pipe head 711, an auxiliary cotton board 712 and a sleeve hole 713; a connecting plate 702 is fixedly provided at the bottom end of the connecting box body 701, a mounting hole is provided on the connecting plate 702, and a mounting screw passes through the mounting hole and is threadedly connected to the connecting screw groove 604 on the clamping body 601, an air suction connecting pipe 703 is provided on one side of the connecting box body 701, and a loading tank body 704 is provided at the box mouth position of the connecting box body 701, and the loading tank body 70 4 is embedded with a first magnetic block 705, and auxiliary clamping strips 707 are symmetrically fixedly arranged at both ends of the loading frame 706, and a handle 708 is arranged on the auxiliary clamping strip 707, and a second magnetic block 709 is embeddedly arranged on one side of the auxiliary clamping strip 707; here, absorption holes 710 are equidistantly arranged in the loading frame 706, and a cone tube head 711 is fixedly arranged on one side of the absorption hole 710, and the large port of the cone tube head 711 is connected to the orifice of the absorption hole 710, and the auxiliary cotton board 712 is equidistantly arranged with sleeve holes 713, and the auxiliary cotton board 712 is placed in the loading frame 706, and the sleeve holes 713 correspond to the setting position of the cone tube head 711, and the number of setting groups is the same, and the aperture of the sleeve holes 713 is larger than the small port diameter of the cone tube head 711, and smaller than the large port diameter of the cone tube head 711.

[0029] The welding auxiliary component in this embodiment is arranged at the top position of the clamping body 601, that is, during the welding process, the smoke generated by welding is absorbed by the suction connection pipe 703 to avoid the smoke generated from affecting the operator and the working environment as much as possible. The loading frame 706 is used in conjunction with the auxiliary cotton board 712. On the one hand, the loading frame 706 is detachably arranged, and an absorption hole 710 is arranged in the loading frame 706. A cone pipe head 711 is arranged at the outer opening position of the absorption hole 710. The cone pipe head 711 cooperates with the auxiliary cotton board 712. In use, the auxiliary cotton plate 712 is installed and used by clamping with the conical tube head 711 through the sleeve hole 713 provided therein. When the conical tube head 711 is inhaling, the absorbed impurities will adhere to the auxiliary cotton plate 712 if they do not pass through the conical tube head 711 and enter the connecting box body 701. The auxiliary cotton plate 712 provided therein is also very convenient to disassemble and assemble, which is convenient for later disassembly, cleaning or replacement. The welding auxiliary assembly as a whole can also be disassembled and assembled, that is, a connecting plate 702 is provided at the bottom end of the connecting box body 701 to be fixedly connected to the clamping body 601 and fastened by screws.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A negative electrode welding machine for large cylindrical battery assembly, characterized in that: It comprises a welding machine workbench (1), a welding mechanism (2), a protective auxiliary component and a welding clamping component; The welding machine workbench (1) is provided with a welding mechanism (2), and the welding mechanism (2) is connected to a welding head (21); The welding machine workbench (1) is provided with a protective auxiliary component and a welding clamping component; The welding clamping assembly is arranged in the supporting cylinder (4); a fixing plate (41) is fixedly arranged at the bottom end of the supporting cylinder (4); and the fixing plate (41) is fixedly arranged on the welding machine workbench (1) by means of screws; The welding clamping assembly clamps and fixes the cylindrical battery (3); The protective auxiliary component comprises a limiting cylinder (501), a connecting ring body (502), a mounting slot (503), a movable column (504), a protective groove (505), an auxiliary spring (506), and a mounting clamping plate (507); a connecting ring body (502) is fixedly arranged at the bottom end of the limiting cylinder (501); the connecting ring body (502) is fixedly arranged on the welding machine workbench (1) by means of screws; a mounting slot (503) is arranged at the bottom end of the connecting ring body (502); a threaded groove is arranged in the mounting slot (503); and the movable column (504) is movably arranged in the limiting cylinder (501); The connecting ring body (502) is arranged in the supporting cylinder body (4), and the center lines of the two are on the same straight line.

2. The negative electrode welding machine for large cylindrical battery assembly according to claim 1, characterized in that: The top end of the movable column (504) is provided with a protective groove (505), the bottom end of the movable column (504) is fixedly provided with an auxiliary spring (506), the bottom end of the auxiliary spring (506) is fixedly provided on a mounting card plate (507), the mounting card plate (507) is adapted to be clamped in the mounting card slot (503), and the mounting card plate (507) is fixed by screws.

3. The negative electrode welding machine for large cylindrical battery assembly according to claim 1, characterized in that: The welding clamping assembly comprises a clamping body (601), a rubber auxiliary strip (602), a movable insert strip (603), a connecting screw groove (604), a transmission column (605), a driving groove body (606), an internal thread regulating disk (607) and an auxiliary handle (608); the movable insert strip (603) is equidistantly and movably inserted in the support cylinder (4); one end of the movable insert strip (603) extends to the inside of the support cylinder (4) and the clamping body (601) is fixedly arranged at the end; the other end of the movable insert strip (603) extends to the outside of the support cylinder (4) and the transmission column (605) is fixedly arranged at the end; one end of the rubber auxiliary strip (602) extends to the driving groove body (606); and a connecting screw groove (604) is arranged on one side of the top of the clamping body (601).

4. The negative electrode welding machine for large cylindrical battery assembly according to claim 3, characterized in that: The inner side wall of the movable insert strip (603) is arranged as an arc-shaped surface, and rubber auxiliary strips (602) are fixedly arranged at equal intervals on the arc-shaped surface.

5. The negative electrode welding machine for large cylindrical battery assembly according to claim 3, characterized in that: The driving groove body (606) is equidistantly arranged at the bottom end of the internal thread regulating disk (607); the internal thread regulating disk (607) is threadedly connected to the outer wall of the supporting cylinder (4); and an auxiliary handle (608) is equidistantly fixedly arranged at the top end of the internal thread regulating disk (607).

6. The negative electrode welding machine for large cylindrical battery assembly according to claim 3, characterized in that: The driving slot bodies (606) and the transmission columns (605) are provided in the same number of groups, and the driving slot bodies (606) are arranged in an arc shape.

7. The negative electrode welding machine for large cylindrical battery assembly according to claim 3, characterized in that: The connecting screw groove (604) is connected to a welding auxiliary component, and the welding auxiliary component comprises a connecting box body (701), a connecting plate (702), an air suction connecting pipe (703), a loading slot body (704), a first magnetic block (705), a loading frame body (706), an auxiliary clamping strip (707), a handle (708), a second magnetic block (709), an absorption hole (710), a conical tube head (711), an auxiliary cotton plate (712) and a sleeve hole (713); a connecting plate (702) is fixedly arranged at the bottom end of the connecting box body (701), and a connecting plate (702) is arranged on the connecting plate (702). The mounting screw passes through the mounting hole and is threadedly connected to the connecting screw groove (604) on the clamping body (601); an air suction connecting pipe (703) is arranged on one side of the connecting box body (701); a loading slot body (704) is arranged at the box mouth of the connecting box body (701); a first magnetic block (705) is embedded in the loading slot body (704); auxiliary clamping strips (707) are symmetrically fixed at both ends of the loading frame body (706); a handle (708) is arranged on the auxiliary clamping strip (707); and a second magnetic block (709) is embedded on one side of the auxiliary clamping strip (707).

8. The negative electrode welding machine for large cylindrical battery assembly according to claim 7, characterized in that: The loading frame (706) is provided with absorption holes (710) at equal intervals, and a conical tube head (711) is fixedly provided on one side of the absorption hole (710), the large end of the conical tube head (711) is connected to the hole mouth of the absorption hole (710), the auxiliary cotton board (712) is provided with sleeve holes (713) at equal intervals, the auxiliary cotton board (712) is placed in the loading frame (706), the sleeve holes (713) and the conical tube head (711) are arranged at corresponding positions and have the same number of groups, and the diameter of the sleeve holes (713) is larger than the diameter of the small end of the conical tube head (711) and smaller than the diameter of the large end of the conical tube head (711).

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