A large cylindrical battery assembling negative electrode welding machine

Abstract

The application relates to the technical field of laser welding processing, in particular to a negative electrode welding machine for assembling large cylindrical batteries, which mainly provides positioning function by arranging a matched cylindrical battery clamping and positioning assembly in a supporting cylinder; improves the welding processing flexibility; furthermore, by arranging a corresponding protection auxiliary assembly in the supporting cylinder, the anode head at the bottom end of the cylindrical battery is protected by the protection auxiliary assembly when the negative electrode at one end of the cylindrical battery is welded, so that damage of the anode head in the processing and positioning process is avoided, the protection auxiliary assembly also has a horizontal correction function for the cylindrical battery; the quality of the negative electrode welding process is ensured; the welding auxiliary assembly is further arranged on the welding clamping assembly and has an absorption function for the smoke generated in the welding process, so that pollution to the working environment and influence on the work of the workers are avoided as much as possible.

Description

TECHNICAL FIELD

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

[0002] The file with the existing announcement number CN116160112A discloses a large cylindrical lithium battery manufacturing laser welding and assembly production line, which includes a sorting box, a speed line body, a detection box, an operation box, a first welding box, a turnover mechanism, a second welding box, a blanking and transferring box, and an assembly line body. The initial end of the speed line body is connected with the terminal end of the sorting box, and the speed line body sequentially passes through the detection box, the operation box, the first welding box, the turnover mechanism, and the second welding box. The terminal end of the speed line body is connected with the initial end of the blanking and transferring box. The terminal end of the blanking and transferring box is connected with the initial end of the assembly line body. This solves the problem that the demand for large cylindrical battery modules is gradually increasing, and the production efficiency for large cylindrical battery modules also needs to be gradually improved, but the existing production device cannot meet the needs of automatic production of detection, sorting, assembly, and spot welding of large cylindrical battery cells.

[0003] The existing negative electrode welding processing of large cylindrical batteries is generally carried out by corresponding welding machines, which have high welding work efficiency in mass production. In the reprocessing process of small batches or missed or unqualified products on the welding production line, the 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 mechanism is used for welding processing. In this process, when welding the negative electrode end of the cylindrical battery, the anode head is below. The existing welding fixing tooling lacks a suitable protection function for the anode head, which is easy to cause collision damage to the position of the anode head. Moreover, when vertically positioning, whether the negative electrode end surface of the cylindrical battery is in a horizontal position cannot be confirmed, which has a certain influence on the subsequent welding processing quality. In addition, the smoke generated during the welding process also affects the workers. Therefore, the existing battery welding processing device lacks a suitable auxiliary mechanism to meet the welding processing needs.

[0004] Therefore, the present application provides a negative electrode welding machine for assembling large cylindrical batteries to solve the above problems. SUMMARY

[0005] The present application aims to provide a negative electrode welding machine for assembling large cylindrical batteries to solve the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solution: a negative electrode welding machine for assembling large cylindrical batteries, comprising a welding machine workbench, a welding mechanism, a protection auxiliary assembly, and a welding clamping assembly.

[0007] The welding machine workbench is provided with a welding mechanism, and a welding head is connected to the welding mechanism;

[0008] The welding machine workbench is provided with a protection auxiliary assembly and a welding clamping assembly;

[0009] The welding clamping assembly is arranged in a supporting cylinder, and a fixed plate is fixedly arranged at the bottom end of the supporting cylinder and fixed on the welding machine workbench by screws;

[0010] The welding clamping assembly clamps and fixes the cylindrical battery.

[0011] Preferably, the protection auxiliary assembly comprises a limiting cylinder, a connecting ring, a mounting clamping groove, a movable column, a protection groove, an auxiliary spring, and a mounting clamping plate. The bottom end of the limiting cylinder is fixedly provided with the connecting ring, which is fixed on the welding machine workbench by screws. The bottom end of the connecting ring is provided with the mounting clamping groove, and a threaded groove is arranged in the mounting clamping groove. The movable column is movably arranged in the limiting cylinder.

[0012] Preferably, the connecting ring is arranged in the supporting cylinder, and the center lines of the two are on the same straight line.

[0013] Preferably, the top end of the movable column is provided with the protection groove, and the bottom end of the movable column is fixedly provided with the auxiliary spring. The bottom end of the auxiliary spring is fixedly arranged on the mounting clamping plate. The mounting clamping plate is adaptively clamped in the mounting clamping groove, and the mounting clamping plate is fixed by screws.

[0014] Preferably, the welding clamping assembly comprises a clamping body, a rubber auxiliary strip, a movable plug strip, a connecting screw groove, a transmission column, a driving groove body, an internal thread control disc, and an auxiliary handle. The movable plug strip is equidistantly movably arranged in the supporting cylinder. One end of the movable plug strip extends to the inside of the supporting cylinder, and the end is fixedly provided with the clamping body. The other end of the movable plug strip extends to the outside of the supporting cylinder, and the end is fixedly provided with the transmission column. One end of the rubber auxiliary strip extends to the driving groove body. The top side of the clamping body is provided with the connecting screw groove.

[0015] Preferably, the inner side wall of the movable plug strip is provided with an arc surface, and the arc surface is equidistantly fixedly provided with the rubber auxiliary strip.

[0016] Preferably, the driving groove body is equidistantly arranged at the bottom end of the internal thread control disc. The internal thread control disc is threadedly connected to the outer side wall of the supporting cylinder. The top end of the internal thread control disc is equidistantly fixedly provided with the auxiliary handle.

[0017] Preferably, the driving groove body and the transmission column are arranged in the same number, and the driving groove body is provided with an arc shape.

[0018] Preferably, the connecting screw groove is connected with a welding auxiliary assembly, the welding auxiliary assembly comprises a connecting box body, a connecting plate, an air suction connecting pipe, a loading groove body, a first magnetic block, a loading frame body, an auxiliary clamping strip, a handle, a second magnetic block, an absorption hole, a tapered pipe head, an auxiliary cotton plate and a sleeve hole; the bottom end of the connecting box body is fixedly provided with the connecting plate, the connecting plate is provided with a mounting hole, a mounting screw passes through the mounting hole and is threadedly connected with the connecting screw groove on the clamping body, one side of the connecting box body is provided with the air suction connecting pipe, the box opening position of the connecting box body is provided with the loading groove body, the loading groove body is embeddedly provided with the first magnetic block, the two ends of the loading frame body are symmetrically fixedly provided with the auxiliary clamping strip, the auxiliary clamping strip is provided with the handle, and one side of the auxiliary clamping strip is embeddedly provided with the second magnetic block.

[0019] Preferably, the loading frame body is provided with the absorption hole at equal intervals, one side of the absorption hole is fixedly provided with the tapered pipe head, the large end port of the tapered pipe head is connected with the hole port of the absorption hole, the auxiliary cotton plate is provided with the sleeve hole at equal intervals, the auxiliary cotton plate is placed in the loading frame body, the sleeve hole and the tapered pipe head are arranged in a corresponding position, have the same number of groups, and the hole diameter of the sleeve hole is greater than the small end diameter of the tapered pipe head and less than the large end diameter of the tapered pipe head.

[0020] Compared with the prior art, the beneficial effects of the present application are:

[0021] The large cylindrical battery negative electrode welding machine designed in the present application mainly provides positioning function by arranging a matched cylindrical battery clamping assembly in the supporting cylinder, improves the welding processing flexibility, and further arranges a corresponding protection auxiliary assembly in the supporting cylinder, so that the anode head at the bottom end of the cylindrical battery is protected by the protection auxiliary assembly during welding processing of the negative electrode at one end of the cylindrical battery, the damage of the anode head during the processing and positioning process is avoided, the quality of the product body is ensured, and on this basis, the protection auxiliary assembly also has a horizontal correction effect on the cylindrical battery, ensuring the quality of the negative electrode welding processing; the welding clamping assembly is further provided with a welding auxiliary assembly, the cooperation of the connecting box body, the air suction connecting pipe and the loading frame body has an absorption effect on the smoke generated during the welding processing, so as to avoid pollution to the working environment and influence on the work of the workers; the present application provides an auxiliary mechanism matched with the battery welding processing device to meet the welding processing requirement. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a large cylindrical battery welding device structure connection schematic diagram of the present application;

[0023] Figure 2 It is a large cylindrical battery welding device structure connection schematic diagram of the present application; Figure 1 It is an enlarged schematic diagram of the structure connection in the present application

[0024] Figure 3 It is a top view of the structure connection of the welding clamping assembly of the auxiliary assembly of the application;

[0025] Figure 4 It is a top view of the structure connection of the welding clamping assembly of the auxiliary assembly of the application; Figure 3 It is an enlarged schematic view of the structure connection at B in the application;

[0026] Figure 5 It is a top view of the structure connection of the welding clamping assembly of the auxiliary assembly of the application; Figure 3 It is an enlarged schematic view of the structure connection at C in the application;

[0027] Figure 6 It is a bottom view of the structure connection of the welding clamping assembly of the auxiliary assembly of the application;

[0028] Figure 7 It is a bottom view of the structure connection of the welding clamping assembly of the auxiliary assembly of the application; Figure 6 It is an enlarged schematic view of the structure connection at D in the application;

[0029] Figure 8 It is an enlarged schematic view of the structure connection at E in the application; Figure 6

[0030] It is an exploded right side view of the structure connection of the welding auxiliary assembly of the application; Figure 9

[0031] It is an enlarged schematic view of the structure connection at F in the application; Figure 10 Figure 9 It is an exploded left side view of the structure connection of the welding auxiliary assembly of the application;

[0032] Figure 11 It is an enlarged schematic view of the structure connection at G in the application.

[0033] Figure 12 In the figure: welding machine workbench 1, welding mechanism 2, welding head 21, cylindrical battery 3, support cylinder 4, fixed plate 41, limiting cylinder 501, connecting ring 502, mounting clamping groove 503, movable column 504, protection groove 505, auxiliary spring 506, mounting clamping plate 507, clamping body 601, rubber auxiliary strip 602, movable insertion strip 603, connecting screw groove 604, transmission column 605, drive groove 606, internally threaded control disc 607, auxiliary handle 608, connecting box 701, connecting plate 702, air suction connecting pipe 703, loading groove 704, first magnetic block 705, loading frame 706, auxiliary clamping strip 707, handle 708, second magnetic block 709, absorption hole 710, conical pipe head 711, auxiliary cotton board 712, sleeve hole 713. Figure 11 DETAILED DESCRIPTION

[0034] DETAILED DESCRIPTION

[0035] ​​The technical solutions in the embodiments of the present application will be clearly and completely described below. All other embodiments obtained by those skilled in the art without creative efforts on the basis of the embodiments in the present application belong to the scope of protection of the present application.

[0036] Embodiment one: please refer to Figures 1-12 A large cylindrical battery negative electrode welding machine, comprising a welding machine workbench 1, a welding mechanism 2, a protection auxiliary assembly and a welding clamping assembly; wherein the welding mechanism 2 is arranged on the welding machine workbench 1, and a welding head 21 is arranged on the welding mechanism 2; the protection auxiliary assembly and the welding clamping assembly are arranged on the welding machine workbench 1; the welding clamping assembly clamps and fixes the cylindrical battery 3, the cylindrical battery 3 is clamped and fixed through the arranged welding clamping assembly, at the same time, the protection auxiliary assembly arranged has a protection effect on the bottom end anode head of the cylindrical battery 3, which avoids damage to the anode head caused by extrusion during negative electrode welding processing; after the cylindrical battery 3 is clamped and positioned, the cylindrical battery 3 is welded and processed through the welding head 21.

[0037] The welding clamping assembly is arranged in the support cylinder 4, and the bottom end of the support cylinder 4 is fixedly provided with a fixed plate 41, which is fixedly arranged on the welding machine workbench 1 through screws; wherein the welding clamping assembly in the support cylinder 4 can be adapted and fastened to cylindrical batteries 3 of different models, and the welding flexibility is high.

[0038] The present application mainly provides positioning function by arranging the cylindrical battery 3 clamping and positioning assembly in the support cylinder 4; improves the welding flexibility; further, by arranging the corresponding protection auxiliary assembly in the support cylinder 4, when the negative electrode at one end of the cylindrical battery 3 is welded and processed, the anode head at the bottom end of the cylindrical battery 3 is protected by the protection auxiliary assembly, which avoids damage to the anode head during processing and positioning, and ensures the quality of the product body.

[0039] Embodiment two: on the basis of embodiment one, please refer to Figures 2-8The protection auxiliary assembly comprises a limiting cylinder 501, a connecting ring body 502, a mounting clamping groove 503, a movable column 504, a protection groove 505, an auxiliary spring 506, and a mounting clamping plate 507. The bottom end of the limiting cylinder 501 is fixedly provided with the connecting ring body 502. The connecting ring body 502 is fixedly provided on the welding machine workbench 1 by a screw. The bottom end of the connecting ring body 502 is provided with the mounting clamping groove 503. The mounting clamping groove 503 is provided with a threaded groove. 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. The movable column 504 is provided with the protection groove 505 at the top end. The bottom end of the movable column 504 is fixedly provided with the auxiliary spring 506. The bottom end of the auxiliary spring 506 is fixedly provided on the mounting clamping plate 507. The mounting clamping plate 507 is adaptively clamped in the mounting clamping groove 503. The mounting clamping plate 507 is fixed by a screw.

[0040] When the cylindrical battery 3 is clamped and positioned, the cylindrical battery 3 is placed in the supporting cylinder body 4. The bottom end of the cylindrical battery 3 is in contact with the movable column 504. The anode head of the bottom end of the cylindrical battery 3 enters the protection groove 505, without being extruded. The cylindrical battery 3 can be pressed down for position adjustment. In this process, the movable column 504 is retracted into the limiting cylinder 501. The movable column 504 supports the bottom end of the cylindrical battery 3, and also makes the bottom end of the cylindrical battery 3 in a horizontal state. Then the welding clamping assembly is used for clamping and positioning.

[0041] The welding clamping assembly comprises a clamping body 601, a rubber auxiliary strip 602, a movable insertion strip 603, a connecting screw groove 604, a transmission column 605, a drive groove body 606, an internal thread control disc 607, and an auxiliary handle 608. The movable insertion strip 603 is equidistantly movably inserted into the supporting cylinder body 4. One end of the movable insertion strip 603 extends to the inside of the supporting cylinder body 4, and the end is fixedly provided with the clamping body 601. The other end of the movable insertion strip 603 extends to the outside of the supporting cylinder body 4, and the end is fixedly provided with the transmission column 605. One end of the rubber auxiliary strip 602 extends to the drive groove body 606. The top side of the clamping body 601 is provided with the connecting screw groove 604. The drive groove body 606 is equidistantly arranged at the bottom end of the internal thread control disc 607. The internal thread control disc 607 is screwedly connected to the outer side wall of the supporting cylinder body 4. The top end of the internal thread control disc 607 is equidistantly fixedly provided with the auxiliary handle 608. The drive groove body 606 and the transmission column 605 are arranged in the same number of groups. The drive groove body 606 is arranged in an arc shape.

[0042] After the position of the cylindrical battery 3 is adjusted, the inner threaded control disc 607 is rotated through the auxiliary handle 608, the inner threaded control disc 607 drives the driving groove 606 at the bottom end to extrude and drive the transmission cylinder 605, thereby moving the movable plug 603, so that the clamping body 601 extrudes the side wall of the cylindrical battery 3. Here, the inner side wall of the movable plug 603 is provided as an arc surface, and rubber auxiliary strips 602 are fixedly arranged at equal intervals on the arc surface. On the basis of stable clamping and positioning, the side wall of the cylindrical battery 3 also has a protection effect, avoiding extrusion damage to the side wall of the cylindrical battery 3 due to excessive clamping force. After the positioning work is completed, welding processing can be performed through the welding mechanism 2.

[0043] The protection auxiliary assembly provided in the support cylinder 4 can also play a convenient material taking role after welding is completed, that is, after welding is completed, the inner threaded control disc 607 is counterclockwise rotated, the inner threaded control disc 607 drives the clamping body 601 to move, and the contact with the cylindrical battery 3 is released. At the same time, the cylindrical battery 3 is lifted up under the action of the movable column 504 and the auxiliary spring 506, which is convenient for the operator to take it down.

[0044] Example three: on the basis of example two, please refer to Figures 9-12 The connecting screw groove 604 is connected and arranged with the welding auxiliary assembly, and the welding auxiliary assembly comprises a connecting box body 701, a connecting plate 702, an air suction connecting pipe 703, a loading groove 704, a first magnetic block 705, a loading frame 706, an auxiliary clamping strip 707, a handle 708, a second magnetic block 709, an absorption hole 710, a tapered pipe head 711, an auxiliary cotton plate 712, and a sleeve hole 713. The bottom end of the connecting box body 701 is fixedly provided with the connecting plate 702, the connecting plate 702 is provided with a mounting hole, a mounting screw passes through the mounting hole and is threadedly connected with the connecting screw groove 604 on the clamping body 601, one side of the connecting box body 701 is provided with the air suction connecting pipe 703, the box opening position of the connecting box body 701 is provided with the loading groove 704, the loading groove 704 is embeddedly connected with the first magnetic block 705, the two ends of the loading frame 706 are symmetrically fixedly provided with the auxiliary clamping strip 707, the auxiliary clamping strip 707 is provided with the handle 708, and one side of the auxiliary clamping strip 707 is embeddedly connected with the second magnetic block 709. The loading frame 706 is provided with the absorption hole 710 at equal intervals, one side of the absorption hole 710 is fixedly provided with the tapered pipe head 711, the large end of the tapered pipe head 711 is connected with the hole opening of the absorption hole 710, the auxiliary cotton plate 712 is provided with the sleeve hole 713 at equal intervals, the auxiliary cotton plate 712 is placed in the loading frame 706, the sleeve hole 713 corresponds to the setting position of the tapered pipe head 711, the setting group number is the same, the hole diameter of the sleeve hole 713 is greater than the small end diameter of the tapered pipe head 711, and less than the large end diameter of the tapered pipe head 711.

[0045] The welding auxiliary assembly in the embodiment is arranged at the top end of the clamping body 601, that is, during the welding process, the welding generated smoke is absorbed through the air connection pipe 703, so as to avoid the influence of the generated smoke on the operator and the working environment. The loading frame body 706 is used in cooperation with the auxiliary cotton board 712. On the one hand, the loading frame body 706 is detachably arranged, and the loading frame body 706 is provided with an absorption hole 710. The outer hole of the absorption hole 710 is provided with a taper pipe head 711. The taper pipe head 711 is used in cooperation with the auxiliary cotton board 712. The auxiliary cotton board 712 is installed and used through the clamping of the sleeve hole 713 and the taper pipe head 711. When the taper pipe head 711 absorbs air, the impurities absorbed by the taper pipe head 711 will also adhere to the auxiliary cotton board 712 when they enter the connection box body 701 without passing through the taper pipe head 711. The auxiliary cotton board 712 is very convenient to disassemble and assemble, and is convenient for disassembly, cleaning or replacement in the later period. The whole welding auxiliary assembly can also be disassembled and assembled, that is, the bottom end of the connection box body 701 is provided with a connecting plate 702 which is fixedly connected with the clamping body 601, and is fastened by a screw.

[0046] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A large cylindrical battery assembling negative electrode welding machine, characterized by: The system includes a welding machine workbench (1), a welding mechanism (2), a protective auxiliary component, and a welding clamping component. The welding machine workbench (1) is equipped with the welding mechanism (2), and a welding head (21) is connected to the welding mechanism (2). The welding machine workbench (1) is equipped with a protective auxiliary component and a welding clamping component. The welding clamping component is housed in a support cylinder (4), and a fixing plate (41) is fixedly installed at the bottom end of the support cylinder (4). The fixing plate (41) is fixed to the welding machine workbench (1) by screws. The welding clamping component clamps and fixes the cylindrical battery (3). The protective auxiliary component includes a limiting cylinder (501). The components include a connecting ring (502), a mounting slot (503), a movable column (504), a protective groove (505), an auxiliary spring (506), and a mounting plate (507). The bottom end of the limiting cylinder (501) is fixedly provided with a connecting ring (502), which is fixedly mounted on the welding machine workbench (1) by screws. The bottom end of the connecting ring (502) is provided with a mounting slot (503), which has a threaded groove. The movable column (504) is movably mounted in the limiting cylinder (501). The connecting ring (502) is set in the supporting cylinder (4), and the center lines of both are on the same straight line. The top of the movable column (504) is provided with a protective groove (505), and the bottom of the movable column (504) is fixedly provided with an auxiliary spring (506). The bottom of the auxiliary spring (506) is fixedly provided on the mounting plate (507). The mounting plate (507) is adapted to be inserted into the mounting slot (503). The mounting plate (507) is fixed by screws. The welding clamping assembly includes a clamping body (601), a rubber auxiliary strip (602), a movable insert (603), a connecting screw groove (604), a transmission column (605), a drive groove (606), an internal thread adjustment disc (607), and an auxiliary handle (608). One end of the rubber auxiliary strip (602) extends into the drive groove (606).

2. A large cylindrical battery negative electrode welding machine according to claim 1, characterized in that: The movable insert (603) is equidistantly inserted into the support cylinder (4). One end of the movable insert (603) extends into the support cylinder (4) and is fixedly provided with a clamping body (601) at the end. The other end of the movable insert (603) extends into the outside of the support cylinder (4) and is fixedly provided with a transmission column (605) at the end. A connecting screw groove (604) is provided on one side of the top of the clamping body (601).

3. A large cylindrical battery negative electrode welding machine according to claim 1, characterized in that: The inner wall of the movable insert (603) is set as an arc-shaped surface, and rubber auxiliary strips (602) are fixedly arranged at equal intervals on the arc-shaped surface.

4. The large cylindrical battery negative electrode welding machine according to claim 1, characterized by: The drive groove (606) is equidistantly arranged at the bottom end of the internal thread control plate (607), the internal thread control plate (607) is threadedly connected to the outer side wall of the support cylinder (4), and the top end of the internal thread control plate (607) is fixedly provided with auxiliary handles (608) at equal intervals.

5. A large cylindrical battery negative electrode welding machine according to claim 1, characterized in that: The driving groove body (606) is arranged in the same number of groups as the transmission column body (605), and the driving groove body (606) is arranged in an arc shape.

6. A large cylindrical battery negative electrode welding machine according to claim 1, characterized in that: The connecting screw groove (604) is connected with the welding auxiliary assembly, and the welding auxiliary assembly comprises a connecting box body (701), a connecting plate (702), an air suction connecting pipe (703), a loading groove (704), a first magnetic block (705), a loading frame (706), an auxiliary clamping strip (707), a handle (708), a second magnetic block (709), an absorption hole (710), a tapered pipe head (711), an auxiliary cotton board (712) and a sleeve hole (713). The bottom end of the connecting box body (701) is fixedly provided with the connecting plate (702), and the connecting plate (702) is provided with a mounting hole. A mounting screw passes through the mounting hole and is threadedly connected with the connecting screw groove (604) on the clamping body (601). One side of the connecting box body (701) is provided with the air suction connecting pipe (703), and the box opening of the connecting box body (701) is provided with the loading groove (704). The loading groove (704) is embeddedly provided with the first magnetic block (705). The loading frame (706) is symmetrically fixedly provided with the auxiliary clamping strip (707) at both ends. The auxiliary clamping strip (707) is provided with the handle (708), and one side of the auxiliary clamping strip (707) is embeddedly provided with the second magnetic block (709).

7. A large cylindrical battery negative electrode welding machine according to claim 6, characterized in that: The loading frame (706) is provided with the absorption hole (710) at equal intervals, and one side of the absorption hole (710) is fixedly provided with the tapered pipe head (711). The large end of the tapered pipe head (711) is connected with the hole of the absorption hole (710). The auxiliary cotton board (712) is provided with the sleeve hole (713) at equal intervals. The auxiliary cotton board (712) is placed in the loading frame (706). The sleeve hole (713) corresponds to the setting position of the tapered pipe head (711) and is arranged in the same number of groups. The hole diameter of the sleeve hole (713) is greater than the small end diameter of the tapered pipe head (711) and less than the large end diameter of the tapered pipe head (711).

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