CN113020868A

CN113020868A - Welding method of underframe assembly, underframe assembly and concrete pump truck with same

Info

Publication number: CN113020868A
Application number: CN202110274703.3A
Authority: CN
Inventors: 蓝才红; 吴香清; 倪川皓; 谭芝芝; 蒋海刚
Original assignee: Zoomlion Heavy Industry Science and Technology Co Ltd
Current assignee: Zoomlion Heavy Industry Science and Technology Co Ltd
Priority date: 2021-03-15
Filing date: 2021-03-15
Publication date: 2021-06-25

Abstract

The invention relates to the field of engineering vehicle underframe, and discloses a welding method of an underframe assembly, the underframe assembly and a concrete pump truck with the underframe assembly, wherein the underframe assembly comprises an underframe main body (100) and an auxiliary frame (200) welded to a bottom plate (110) of the underframe main body (100), and the welding method comprises the following steps: s1, a welding plate positioning welding step, namely positioning a welding plate (400) by using a welding plate positioning tool (500) so as to position-weld the welding plate (400) to the bottom plate (110); s2, a step of positioning and welding the auxiliary frame (200), namely placing and welding the auxiliary frame to a welding position, limited by the welding plate (400), on the bottom plate (110). According to the invention, the welding position of the welding plate can be ensured to coincide with the center of the chassis main body by utilizing the welding plate positioning tool, so that the auxiliary frame can be ensured to be accurately welded to the preset welding position, and therefore, the auxiliary frame has higher positioning precision when being assembled to the lower vehicle chassis and is convenient for quick and accurate assembly.

Description

Welding method of underframe assembly, underframe assembly and concrete pump truck with same

Technical Field

The invention relates to an engineering vehicle chassis, in particular to a welding method of a chassis assembly. In addition, the invention also relates to the underframe assembly manufactured by the welding method and a concrete pump truck comprising the underframe assembly.

Background

In an engineering vehicle such as a concrete pump truck, an underframe box type structural member serves as an intermediate member connected to a vehicle chassis and an upper vehicle part and plays a role in supporting and fixing in the working process, and the manufacturing precision of the underframe box type structural member has an important influence on the subsequent assembly efficiency, the handling performance of vehicle operation, the service life and the like.

Disclosure of Invention

The invention aims to overcome the problem that the manufacturing precision of a chassis assembly is difficult to ensure in the prior art, and provides a welding method of the chassis assembly.

In order to achieve the above object, an aspect of the present invention provides a welding method, the chassis assembly including a chassis main body and a sub frame for welding to a bottom plate of the chassis main body, the welding method including: s1, positioning and welding a welded plate, namely positioning and welding the welded plate to the bottom plate by using a welded plate positioning tool; and S2, positioning and welding the auxiliary frame, namely placing and welding the auxiliary frame to a welding position, limited by the welding plate, on the bottom plate.

Preferably, step S1 includes: s11, marking a central line at the central position of the bottom plate; s12, placing the welding plate positioning tool on the bottom plate, and aligning a central scribed line of the welding plate positioning tool with the central line; s13, placing the welding plate on the bottom plate and pressing and fixing the welding plate by the welding plate positioning tool; s14, welding the welding plate to the bottom plate.

Preferably, the welding plate positioning tool comprises a pair of tool longitudinal beams extending in parallel, a plurality of pressing supports connected to the tool longitudinal beams, and pressing bolts screwed to the pressing supports and capable of being operated to move towards the direction close to or away from the tool longitudinal beams, and in sub-step S13, the welding plate is pressed and fixed to be attached to the outer side faces of the tool longitudinal beams by the pressing bolts.

Preferably, the subframe comprises subframe longitudinal beams and subframe cross beams, and the welding method further comprises a subframe manufacturing step performed before step S2: and the auxiliary frame longitudinal beam is positioned on the auxiliary frame lap tool, and the auxiliary frame cross beam is welded on the auxiliary frame longitudinal beam after the positioning.

Preferably, the subframe further includes a plurality of mounting plates for attachment to the subframe rails, the subframe manufacturing step further includes: and positioning the mounting plate on the auxiliary frame lap tool, and welding the mounting plate to the auxiliary frame longitudinal beam.

Preferably, the auxiliary frame lap tool comprises a positioning platform, an upright post installed on the positioning platform, a bolt connecting block rotatably installed on the upright post, and a compression screw which is in threaded connection with the bolt connecting block and can be operated to move towards or away from the positioning platform, and in the auxiliary frame manufacturing step, the auxiliary frame longitudinal beam is compressed and fixed on the positioning platform through the compression screw.

Preferably, the chassis assembly further includes a pull rod lug, and the welding method further includes: and S3, a pull rod lug seat positioning welding step, namely positioning the pull rod lug seat by utilizing a pull rod lug seat positioning tool after the step S2 so as to position and weld the pull rod lug seat to the chassis main body.

Preferably, step S3 includes: s31, assembling the pull rod lug seat on a positioning shaft of the pull rod lug seat positioning tool, and placing the pull rod lug seat positioning tool to be positioned by the auxiliary frame in multiple directions; s32, welding the pull rod lug seat to the bottom frame main body.

The invention provides a chassis assembly manufactured by the welding method.

The third aspect of the invention provides a concrete pump truck, which comprises a lower truck chassis, an upper truck arm support assembly and the underframe assembly connected between the lower truck chassis and the upper truck arm support assembly.

According to the technical scheme, the welding position of the welding plate can be ensured to coincide with the center of the chassis main body by utilizing the welding plate positioning tool, so that the auxiliary frame can be ensured to be accurately welded to the preset welding position, and therefore, the auxiliary frame has high positioning precision when being assembled to a chassis of a lower vehicle and is convenient to assemble quickly and accurately.

Drawings

FIG. 1 is a top view of a preferred embodiment of a chassis assembly according to the present invention;

FIG. 2 is a bottom view of the chassis assembly of FIG. 1;

FIG. 3 is a cross-sectional view A-A of the chassis assembly of FIG. 1;

FIG. 4 is a schematic view of a chassis body of the chassis assembly of FIG. 1;

FIG. 5 is a schematic view of the structure of FIG. 4 when a weld plate is welded to the chassis body;

FIG. 6 is a front view of a subframe of the chassis assembly of FIG. 1;

FIG. 7 is a top view of the subframe of FIG. 6;

FIG. 8 is a schematic view of the subframe of FIG. 6 welded to the chassis body of FIG. 5 with the weld plate welded thereto;

FIG. 9 is a schematic view of a tension rod ear mount of the chassis assembly of FIG. 1;

FIG. 10 is a top view of a weld plate positioning fixture for use in practicing the weld method of the present invention;

FIG. 11 is a left side view of the weld plate positioning fixture of FIG. 10;

FIG. 12 is a schematic view of the weld plate positioning tool of FIG. 10 being used to perform a weld plate positioning step;

FIG. 13 is a view from the direction G in FIG. 12;

FIG. 14 is a schematic illustration of a sub-frame manufacturing step in a welding method according to a preferred embodiment of the present invention, wherein a sub-frame lap tool is utilized;

FIG. 15 is a cross-sectional view B-B of FIG. 14;

FIG. 16 is a front view of a tie rod ear seat positioning tool for performing the tie rod ear seat positioning welding step in the welding method according to a preferred embodiment of the present invention;

FIG. 17 is a left side view of the pull rod ear mount positioning tooling of FIG. 16;

FIG. 18 is a top view of the pull rod ear mount positioning fixture of FIG. 16;

fig. 19 to 21 are a front view, a right view and a top view of a tie bar ear seat positioning and welding step implemented by the tie bar ear seat positioning tool in fig. 16.

Description of the reference numerals

100-a chassis body; 110-a base plate;

200-an auxiliary frame; 210-subframe stringers; 220-subframe cross beam; 230-a mounting plate;

300-a pull rod ear seat; 310-closing plate; 320-ear plate; 330-pasting a board;

400-welding a plate;

500-welding a plate positioning tool; 510-tooling longitudinal beams; 520-a compression support; 530-hold down bolts;

600-auxiliary frame placing tool; 610-a positioning platform; 620-column; 630-bolt connection block; 640-a compression screw;

700-a pull rod lug seat positioning tool; 710-a positioning frame; 711-first positioning face; 712-a second locating surface; 720-positioning the shaft.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

In order to better understand the welding method of the chassis assembly provided by the present invention, the structure of the chassis assembly according to a preferred embodiment of the present invention will be described first. As shown in fig. 1 to 3, the undercarriage assembly includes an undercarriage body 100 and a subframe 200. In conjunction with fig. 4, the chassis main body 100 may be a large box structure with a hollow interior, which is composed of a plurality of small box structures and a plurality of cylinder structures, and has a bottom plate 110 and other box structures and parts which are swung and welded based on the bottom plate 110, and the bottom plate and the other box structures and parts may be connected to each other by welding.

The sub frame 200 is welded to the lower side of the bottom plate 110 of the underframe body 100 for assembly connection with the lower chassis; the drawbar lug 300 is welded to the chassis body 100 and has a lug hole to be able to serve as a connection base for the diagonal bracing of the arm support assembly. Typically, referring to fig. 6 and 7, the subframe 200 may include a pair of subframe longitudinal members 210 extending in parallel to a center line of the undercarriage body 100 and a plurality of subframe cross members 220 connected between the pair of subframe longitudinal members 210, and a plurality of mounting plates 230 may be welded to the subframe longitudinal members 210, the mounting plates 230 having mounting holes for being assembled to the lower chassis by bolts or the like.

In the manufacturing process of the underframe assembly, the dimensional accuracy between all welding parts, such as the transverse and longitudinal intervals of the mounting holes on adjacent mounting plates, is ensured so as to be smoothly assembled with the lower chassis; for another example, in the preferred embodiment with the tie bar lug 300, it is necessary to ensure the dimensional parameters such as the hole diameter and the coaxiality of the two tie bar lug 300 so as to be correctly assembled with the diagonal bracing and smoothly operate.

Therefore, the invention provides a welding method of an underframe assembly, which comprises the following steps: s1, welding a welding plate in a positioning manner; and S2, performing positioning welding on the auxiliary frame and the like. In step S1, as shown in fig. 12 and 13, the welding plate 400 is positioned by the welding plate positioning tool 500 to weld the welding plate 400 to the bottom plate 110; in step S2, the subframe 200 is placed and welded to the welding position defined by the weld plate 400 on the bottom plate 110.

Therefore, in the welding process, the welding plate positioning tool 500 can be used for ensuring that the symmetry centers of the welding plates 400 on the two sides after welding coincide with the center of the underframe main body 100, and further ensuring that the auxiliary frame 200 is accurately welded to a preset welding position, so that the auxiliary frame 200 has high positioning precision when being assembled to a lower vehicle chassis, and is convenient to assemble quickly and accurately.

On this basis, the welding method of the present invention may further include: and S3, positioning and welding the pull rod lug seat. That is, as shown in fig. 19 to 21, after step S2, the tie bar lug 300 is positioned by the tie bar lug positioning tool 700 to weld the tie bar lug 300 to the chassis body 100, so that the hole diameters and the coaxiality of the two tie bar lugs 300 can be ensured, and the correct assembly with the diagonal bracing can be facilitated.

The steps of the soldering method according to the preferred embodiment of the present invention will be described below:

chassis body fabrication

As described above, the chassis main body 100 is formed by welding a plurality of small box structures to the base plate 110, and all the welding seams of the chassis main body 100 are welded in this process, and the resulting chassis main body 100 is shown in fig. 4.

Weld mounting plate fixed-position welding S1

In this step, the four welding plates 400 are tack-welded to the bottom plate 110 of the chassis body 100 by the welding plate tack tool 500, and the inner side pitch of the welding plates 400 is required to be adapted to the width of the subframe 200. A weld plate positioning tool 500 used in this step is shown in fig. 10 and 11.

With reference to fig. 5, 10 to 13, the weld plate tack welding step S1 may include the following sub-steps:

s11, placing the underframe main body 100 with the bottom plate 110 facing upwards, cleaning sundries such as welding slag on the bottom plate 110, and marking a central line at the central position of the bottom plate 110;

s12, hoisting and placing the welding plate positioning tool 500 on the bottom plate 110, so that the opposite sides of the welding plate positioning tool 500 and the bottom plate 110 are attached, and knocking the welding plate positioning tool 500 (an adjusting baffle thereof) by using a tool to perform left and right fine adjustment so as to align a central scribed line of the welding plate with a central line on the bottom plate 110;

s13, placing the welding plate 400 on the bottom plate 110, aligning the front end and the rear end of the welding plate 400 with the edge of the bottom plate 110 to realize front and rear positioning, pressing the welding plate 400 by using a pressing bolt 530 on the welding plate positioning tool 500, ensuring that the welding plate 400 is attached to the outer side surface of the tool longitudinal beam 510, and realizing left and right positioning;

s14, spot welding and fixing the outer side of the welding plate 400, and welding the outer side welding seam of the welding plate 400 and the bottom plate 110; after cooling, the weld plate positioning work 500 is removed, and the weld on the inside of the weld plate 400 is welded.

According to the above steps, the chassis main body 100 to which the solder plate 400 is welded as shown in fig. 5 is manufactured. In the above process, as shown in fig. 10 and 11, the welding plate positioning tool 500 includes a pair of tool longitudinal beams 510 extending in parallel, a plurality of pressing supports 520 connected to the tool longitudinal beams 510, and a pressing bolt 530 screwed on the pressing supports 520, where the pressing bolt 530 can be operated to move toward and away from the tool longitudinal beams 510, so as to press and fix the welding plate 400 to the tool longitudinal beams 510 in the sub-step S13, so that the welding plate is attached to the outer side surfaces of the tool longitudinal beams 510, thereby achieving left-right positioning.

Subframe manufacture

As described above, in the undercarriage assembly according to a preferred embodiment of the present invention, as shown in fig. 6 and 7, the subframe 200 includes a pair of subframe longitudinal members 210, a subframe cross member 220 connected between the subframe longitudinal members 210, and a plurality of mounting plates 230 connected to the subframe longitudinal members 210, wherein the mounting plates 230 can be used for assembly connection with a lower vehicle chassis.

In the subframe manufacturing process, the positioning welding may be performed using the subframe lap tool 600 shown in fig. 14 and 15. Therefore, the subframe longitudinal beams 210 can be firstly positioned on the positioning platform 610 of the subframe swinging tool 600, and then the subframe cross beams 220 are welded among the subframe longitudinal beams 210; the mounting plate 230 is positioned at a corresponding position on the auxiliary frame lap tool 600, and is further welded to the auxiliary frame longitudinal beam 210. Thereby, it can be ensured that each mounting plate 230 of the manufactured subframe 200 has a size suitable for fitting to the lower chassis.

The subframe manufacturing step may include the substeps of:

firstly, hoisting the auxiliary frame longitudinal beams 210 to a positioning platform 610 of the auxiliary frame erecting tool 600, and accurately positioning the end parts and the side edges of each auxiliary frame longitudinal beam 210 by three positioning seats (not marked); further, the bolt connecting block 630 is rotated relative to the upright column 620, the compression screw 640 rotates around the upright column 620 to be above the subframe longitudinal beam 210, and then the compression screw 640 is screwed to tightly press and fix the subframe longitudinal beam 210 on the positioning platform 610; at this time, the distance between the outer side surfaces of the two subframe longitudinal beams 210 is slightly smaller than the inner side distance between the two welding plates 400 welded to the underframe body 100, so that the subframe 200 can be easily placed at the welding position defined by the welding plates 400 after welding;

secondly, putting an auxiliary frame cross beam 220 between the auxiliary frame longitudinal beams 210, and welding a welding seam between the auxiliary frame cross beam 220 and the auxiliary frame longitudinal beams 210 to obtain a frame body of the auxiliary frame;

thirdly, assembling a plurality of mounting plates 230 on the positioning platform 610 through screws on two sides of the subframe longitudinal beam 210, so that one side of the mounting plate 230 is tightly attached to the subframe longitudinal beam 210, and welding a welding seam between the mounting plate 230 and the subframe longitudinal beam 210; by utilizing the positioning structure on the positioning platform 610, the size between the mounting plates 230 and the position of the auxiliary frame longitudinal beam 210 can be ensured to meet the requirement of size precision;

fourthly, the auxiliary frame swing-up tool 600 is loosened to fix each part of the auxiliary frame 200, the auxiliary frame 200 is hung down and turned over, and a welding seam on the other side is welded.

In the above process, the sub-frame swing-up tool 600 includes a positioning platform 610, a column 620 mounted on the positioning platform 610, a bolt connection block 630 rotatably mounted on the column 620, and a compression screw 640 screwed to the bolt connection block 630 and capable of being operated to move toward or away from the positioning platform 610. In the subframe manufacturing step, the subframe longitudinal beam 210 may be pressed and fixed to the positioning platform 610 by the pressing screw 640, as shown in fig. 15.

Sub-frame fixed-position welding S2

The subframe 200 manufactured by the above-described method is hung between the weld plates 400 in the weldment shown in fig. 5 so that the subframe 200 is attached to the bottom plate 110 of the underframe body 100. The subframe 200 is positioned in the front and rear direction by measurement, and then the welding lines of the subframe 200 and the base plate 110 are welded. In the sub frame tack welding step S2, the undercarriage body 100 to which the weld plate 400 and the sub frame 200 are welded is manufactured as shown in fig. 8.

Pull rod ear seat manufacturing

As shown in fig. 9, the drawbar lug 300 includes a sealing plate 310 for connecting to the chassis body 100 and a pair of lugs 320 extending from the sealing plate 310, the lugs 320 are formed with mounting holes for diagonal support through pivotal axis connection, and two sides of the mounting holes may be provided with attachment plates 330 for improving structural strength.

In manufacturing, the attachment plate 330 is first welded to each side of the mounting hole, and then the ear plate 320 is welded to the sealing plate 310. And (4) transferring the weldment to a machining workshop, and machining the hole and the inner side end face by using a boring machine to ensure the aperture size and the end face distance. Two tie rod ear mounts 300 are fabricated for each chassis assembly.

Pull rod lug seat positioning welding S3

In this step, the two tie bar lugs 300 are tack welded to the chassis body 100 using the tie bar lug positioning tool 700. In the tie bar lug positioning tool 700 shown in fig. 16 to 18, the first positioning surface 711 and the second positioning surface 712 can be used to accurately position the tie bar lug 300 with reference to the upper surface and the outer side surface of the subframe longitudinal beam 210, thereby ensuring the coaxiality of the mounting holes of the two tie bar lugs 300 and the distance between the mounting holes and the bottom plate 110 of the underframe body 100.

Specifically, the drawbar ear seat positioning tool 700 includes a positioning frame 710 and a positioning shaft 720 (short shaft) detachably connected to the positioning frame 710, and the first positioning surface 711 and the second positioning surface 712 are respectively formed on the positioning frame 710 and are perpendicular to each other.

Referring to fig. 19 to 21, in the tie bar lug position welding step S3, the following sub-steps may be included:

s31, the positioning shaft 720 penetrates through the pull rod lug seat 300 and the mounting holes in the positioning frame 710 so that the pull rod lug seat 300 is assembled on the pull rod lug seat positioning tool 700, and at the moment, the pull rod lug seat 300 can rotate around the positioning shaft 720 relatively; the pull rod lug positioning tool 700 is hoisted to the auxiliary frame longitudinal beam 210, so that the first positioning surface 711 is attached to the upper surface of the auxiliary frame longitudinal beam 210, the second positioning surface 712 is attached to the outer side surface of the auxiliary frame longitudinal beam 210, and the front end of the pull rod lug positioning tool 700 abuts against the edge of the upper cover plate of the chassis main body 100, so that positioning in three directions is realized, and the pull rod lug 300 can be welded to a correct position;

s32, rotating the pull rod lug seat 300 around the positioning shaft 720 to enable the sealing plate 310 to be uniformly attached to the underframe main body 100, and fixing by spot welding; the positioning shaft 720 is taken down, the pull rod lug positioning tool 700 is lifted away, and all welding seams between the pull rod lug 300 and the chassis main body 100 are welded.

Thus, the undercarriage assembly shown in fig. 1 to 3 is manufactured. In the welding process, firstly, a welding plate is installed on the chassis main body, and then an auxiliary frame is installed by utilizing the bottom plate of the chassis main body and the welding plate; and after the pull rod lug seats are welded, machining is carried out on the mounting holes, and then the left and right pull rod lug seats are mounted by taking the longitudinal beams of the chassis main body and the auxiliary frame as references. The positioning of each part and weldment is guaranteed by using the tool, the center coincidence of the chassis is guaranteed by using the welding plate positioning tool, the relative sizes of the auxiliary frame longitudinal beam, the auxiliary frame cross beam and each mounting plate are guaranteed by using the auxiliary frame overlapping tool, and the coaxiality of the holes and the distance between the holes and the bottom plate are guaranteed by using the pull rod lug positioning tool. The welding method can meet the positioning accuracy of the assembly after the welding of the underframe assembly, and ensure that the mounting plate on the longitudinal beam of the auxiliary frame and the mounting hole on the pull rod lug can be correctly assembled with other components (a lower vehicle chassis and an inclined pull support). Since the field welding in an assembly shop is eliminated, the underframe main body 100, the subframe 200 and the tie bar lug 300 can be prefabricated in batch before welding, thereby facilitating the improvement of product quality and manufacturing efficiency and the reduction of production cost.

On the basis, the invention also provides the underframe assembly manufactured by the welding method and the concrete pump truck comprising the underframe assembly.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, numerous simple modifications can be made to the technical solution of the invention, including combinations of the individual specific technical features in any suitable way. The invention is not described in detail in order to avoid unnecessary repetition. Such simple modifications and combinations should be considered within the scope of the present disclosure as well.

Claims

1. A welding method of an undercarriage assembly including an undercarriage body (100) and a subframe (200) for welding to a floor (110) of the undercarriage body (100), characterized in that the welding method comprises:

s1, positioning and welding a welding plate, namely positioning and welding the welding plate (400) by using a welding plate positioning tool (500) so as to position and weld the welding plate (400) to the bottom plate (110);

s2, a step of positioning and welding the auxiliary frame (200), namely placing and welding the auxiliary frame to a welding position, limited by the welding plate (400), on the bottom plate (110).

2. The method for welding the chassis assembly according to claim 1, wherein the step S1 includes:

s11, marking a central line at the central position of the bottom plate (110);

s12, placing the welding plate positioning tool (500) on the bottom plate (110), and aligning a central scribing line of the welding plate positioning tool (500) with the central line;

s13, placing the welding plate (400) on the bottom plate (110) and pressing and fixing the welding plate by the welding plate positioning tool (500);

s14, welding the welding plate (400) to the bottom plate (110).

3. The method of claim 2, wherein the tooling plate positioning tooling (500) comprises a pair of tooling stringers (510) extending in parallel, a plurality of pressing brackets (520) connected to the tooling stringers (510), and pressing bolts (530) screwed to the pressing brackets (520) and operable to move toward or away from the tooling stringers (510), and in sub-step S13, the tooling plate (400) is pressed and fixed by the pressing bolts (530) to be attached to the outer side surfaces of the tooling stringers (510).

4. The method of claim 1, wherein the subframe (200) includes subframe rails (210) and subframe cross members (220), and further comprising a subframe manufacturing step performed prior to step S2: and (2) positioning the auxiliary frame longitudinal beam (210) on an auxiliary frame lap-joint tool (600), and welding the auxiliary frame cross beam (220) on the auxiliary frame longitudinal beam (210) after positioning.

5. The method of welding undercarriage assemblies according to claim 4 wherein said subframe (200) further comprises a plurality of mounting plates (230) for attachment to said subframe rails (210), said subframe fabricating step further comprising: and (2) positioning the mounting plate (230) on the auxiliary frame lap tool (600), and welding the mounting plate (230) to the auxiliary frame longitudinal beam (210).

6. The welding method of the underframe assembly of claim 4, wherein the auxiliary frame lap tool (600) comprises a positioning platform (610), a column (620) mounted on the positioning platform (610), a bolt connecting block (630) rotatably mounted on the column (620), and a compression screw (640) screwed to the bolt connecting block (630) and capable of being operated to move toward or away from the positioning platform (610), and in the auxiliary frame manufacturing step, the auxiliary frame longitudinal beam (210) is fixed on the positioning platform (610) by the compression screw (640) in a compression manner.

7. The method of welding of an undercarriage assembly according to any of the claims 1-6, further comprising a tie rod ear mount (300), the method further comprising:

s3, a pull rod lug seat positioning and welding step, namely positioning the pull rod lug seat (300) by using a pull rod lug seat positioning tool (700) after the step S2 so as to position and weld the pull rod lug seat (300) to the chassis main body (100).

8. The method for welding the chassis assembly according to claim 7, wherein the step S3 includes:

s31, assembling the pull rod lug seat (300) on a positioning shaft (720) of the pull rod lug seat positioning tool (700), and placing the pull rod lug seat positioning tool (700) to be positioned by the auxiliary frame (200) in multiple directions;

s32, welding the pull rod lug seat (300) to the chassis main body (100).

9. An undercarriage assembly produced by the welding process according to any one of claims 1 to 8.

10. A concrete pump truck comprising a lower truck chassis, an upper truck boom assembly and the chassis assembly of claim 9 connected between the lower truck chassis and the upper truck boom assembly.