CN205085574U - Knight's car is frame halfbody combination upper portion fixed -position welding anchor clamps structure for sample - Google Patents

Abstract

The utility model discloses a knight's car is frame halfbody combination upper portion fixed -position welding anchor clamps structure for sample, a serial communication port, including the joint block locating component of reinforced company, the top tube middle part connecting plate locating component who is used for realizing top tube middle part connecting plate location, the seatpad bearing board locating component who is used for realizing seatpad bearing board location, the top tube rear portion connecting plate locating component who is used for realizing top tube rear portion connecting plate location that are used for realizing reinforced company joint block location, be used for realizing the back shock attenuation installation axle locating component of back shock attenuation installation shaft locating and being used for realizing the top tube tail end connecting plate locating component of top tube tail end connecting plate location. The utility model discloses can simplify the solder mount process, have easy operation, low cost to can make things convenient for the advantages such as trial -production adjustment of knight's car sample.

Description

A positioning welding fixture structure for the upper part of the frame half body combination for the rider bike sample

technical field

The utility model relates to the field of motorcycle frame processing, in particular to a positioning welding fixture structure for the upper part of the half-body combination of the frame half body for the rider bike sample.

Background technique

Among the motorcycles, riding motorcycles, as a classic model, have the advantages of high power and good long-distance driving performance, and are deeply loved by consumers. At the same time, in the process of motorcycle research and development, it is often necessary to develop and design sample products first, and then conduct tests to ensure the reliability and practicability of the final product.

In a new riding motorcycle with a model number of LF-125-2C, its frame body includes a head tube assembly and two frame halves connected to the left and right sides behind the head tube assembly.

Among them, the head tube assembly includes a head tube mounting frame, the front end of the head tube mounting frame is fixedly connected to the head tube, the rear lower end of the head tube mounting frame is fixedly connected to the downslope pipe, and the rear upper end of the head tube mounting frame is used to pass through a covered reinforced connection block. It is connected with the combined front end of the two frame halves;

Among them, the combined structure of the half body of the frame includes a front down tube which is arranged to be inclined forward and upward as a whole. The front end of the front down tube has a front end which is used to be combined and connected with the head tube assembly after a section of twists and turns and then tilted forward and upward. The connecting section of the pipe assembly, the lower end of the front lower tube is bent forward to form a connecting section of the flat fork shaft mounting plate in the shape of a backward convex arc, and the connecting section of the flat fork shaft mounting plate is welded and fixed forward plate, the lower end of the front lower tube is also welded and fixed horizontally with the front lower tube horizontal connecting sleeve; it also includes a rear lower tube, the rear lower tube is in the shape of a straight tube inclined backward and upward as a whole, and the lower end of the rear lower tube is fixedly connected On the rear side of the connecting section of the flat fork shaft mounting plate at the lower end of the front down tube, the upper end of the rear down tube is connected to an upper tube; the upper tube is set horizontally as a whole and the front end is lapped and fixed on the connecting section of the head tube assembly at the front end of the front down tube , the middle part of the upper tube is bent horizontally inward to form a reinforced connection section, and the rear end of the upper tube has a tail section that extends obliquely upwards and backwards, and the lower surface of the front part of the tail section is fixed to the upper end of the rear lower tube; the upper tube is in order from front to back Two upper tube battery mounting lugs and one upper tube cover mounting lug are fixed downwards; the angle between the upper tube and the rear lower tube is connected with an upper angle reinforcing block with lug holes, and the rear lower There are two mounting lugs for the rear lower tube cover extending forward and upward at intervals on the tube; a lower angle reinforcing block with a positioning hole is connected at the angle between the rear lower tube and the front lower tube, and the lower clamp The corner reinforcement block is welded upwards and fixed with reinforcement block battery mounting lugs; the half-body combined structure of the frame also includes a pedal mounting assembly, which includes one end fixed on the rear side surface of the lower part of the rear lower tube and the other end extending backward and downward. The upper pedal installation tube of the upper pedal also includes a lower pedal installation tube fixed on the rear side surface of the lower end of the front lower tube and the other end extends upward and rearward. The upper pedal installation tube and the lower pedal installation tube intersect and connect at the angle There is a triangular rear angle reinforcing block fixed by welding. The rear angle reinforcing block is used for horizontal welding to fix the rear pedal lug, and the outer end of the connection between the upper pedal mounting tube and the pedal lower mounting tube is also fixed horizontally with the pedal mounting tube Transversely connect the sleeve, and the upper side of the rear part of the upper pedal mounting pipe is also fixedly connected with a triangular rear pedal hanging rod toward the rear and upper side.

The complete LF-125-2C motorcycle frame, on the basis of the main structure of the above frame, also needs to be fixedly connected with a direction lock block on the upper front side of the head tube, and a direction limit block fixedly connected on the lower front side of the head tube , the upper part of the head tube mounting bracket is horizontally penetrated and fixedly connected with a fuel tank clamp shaft, and the lower part of the down tube needs to be installed horizontally with two engine front suspension installation shafts at intervals, and the upper part of the rear side of the down tube needs to be fixed for the installation of a down tube accessory Hanger; at the same time, it is necessary to cover and fix a connecting plate in the middle of the upper tube horizontally on the reinforced connecting section in the middle of the two upper tubes, and a U-shaped seat cushion needs to be fixedly connected between the two upper tubes on the rear side of the reinforced connecting section The supporting plate, the rear part and the tail end of the two upper tubes are also horizontally connected and fixedly provided with the upper tube rear connecting plate and the upper tube tail end connecting plate, and the two sides of the rear part of the two upper tubes also need to be horizontally provided with a Outwardly extending rear shock absorber installation shaft; in addition, it is also necessary to consider setting the engine rear upper suspension installation shaft lug and the engine rear upper suspension installation shaft extending forward and downward in the middle of the front down tube. The rear upper side of the front down tube middle part needs Set the front lower tube reinforced connecting shaft lug and the front down tube reinforced connecting shaft transversely connected between the two front down tube reinforced connecting shaft lugs, and the flat fork shaft mounting plate at the lower part of the front down tube also needs to install the connecting flat fork shaft , the lower end of the front down tube needs to consider setting the forward engine rear suspension mounting shaft lug and the engine rear under suspension mounting shaft, the front down tube lower end also needs to consider setting the rear side bracket mounting plate, and the front down tube is connected horizontally It is necessary to install and fix the transverse connection shaft of the front lower tube in the sleeve; in addition, in the pedal installation assembly, it is also necessary to consider fixing the rear pedal lug outward on the rear angle reinforcing block; Soldering is required to secure the pedal mounting tubes to the transverse connection shaft.

The above-mentioned frame structure, in the production of motorcycle research and development samples, usually divides the work step by step to complete the welding and fixing of the auxiliary components on the head tube assembly; , and finally the combination of the head tube assembly and the half body of the frame is fixed by welding and fixed as a whole by using a jig. Like this, there are numerous working procedures, complicated operation, and the defects that the cost is too high. Especially because sample production often needs to adjust the installation position and installation angle of some local components, in this way, welding fixtures with fixed structures are used for each adjustment, which greatly increases the cost and restricts the expansion of sample research and development.

Especially the structure at the upper part of the vehicle frame half body combination, because of its unique structure, and there are many accessories to be welded, so when considering the structure at the upper part of the vehicle frame half body combination for welding, the above-mentioned defects are particularly obvious.

Utility model content

Aiming at the deficiencies of the above-mentioned prior art, the technical problem to be solved by this utility model is: how to provide a rider bike sample frame that can simplify the process, make it easy to operate, low in cost, and further enable it to be easily trial-manufactured and adjusted. Half-body combined upper positioning welding fixture structure.

In order to solve the above technical problems, the utility model adopts the following technical solutions:

A positioning welding fixture structure for the upper part of the frame half body assembly for the knight car sample, which is characterized in that it includes a reinforcing connection block positioning assembly for realizing the positioning of the strengthening connection block, and a middle part of the upper tube for realizing the positioning of the connecting plate in the middle part of the upper tube Connection plate positioning assembly, seat cushion support plate positioning assembly for positioning seat cushion support plate, upper tube rear connection plate positioning assembly for upper tube rear connection plate positioning, rear shock absorber installation The rear shock absorber installation shaft positioning assembly for shaft positioning and the upper tube tail end connecting plate positioning assembly for realizing the positioning of the upper tube tail end connecting plate.

In this way, the welding fixture structure can realize the positioning and installation of the connecting components between the frame half body assembly and the head tube assembly, as well as the multiple auxiliary components on the upper part of the frame half body assembly. Welding between components. The mutual position accuracy of each component is reliable, and the welding operation is convenient and fast, which saves the cost.

As an optimization, the reinforcing connection block positioning assembly includes a standard square box for positioning the upper tube connecting member with an overall rectangular structure, and each side of the standard square box for positioning the upper tube connecting member is in accordance with the three-dimensional installation platform. The installation holes are arranged in a consistent spacing and aperture array with several installation holes. The standard square box used for the positioning of the upper tube connecting member is fixed on the corresponding position on the rear of the three-dimensional installation platform by bolts. The upper tube connecting member is positioned on the upper front side of the standard square box. There is an overall triangular supporting angle iron for positioning the upper pipe connecting member, and on each side of the supporting angle iron for positioning the upper pipe connecting member, a number of mounting holes are arranged according to the same spacing and aperture array as the mounting holes on the three-dimensional mounting platform. The supporting angle iron for positioning the upper tube connecting member has a vertical connecting surface that is vertically attached to the front side of the standard square box for positioning the upper tube connecting member and is fixedly connected by bolts. The supporting angle for the positioning of the upper tube connecting member The upper surface of the angle iron is an installation plane extending horizontally forward; the positioning component of the reinforced connection block also includes two reinforcements fixed at the middle of the front end of the upper surface of the supporting angle iron for positioning the upper tube connecting member. Connecting block positioning block, the distance between the two reinforced connecting block positioning blocks is greater than the width of the reinforced connecting block, and the upper ends of the two reinforced connecting blocks correspond to the jacks on the reinforced connecting block. There are positioning holes for positioning the reinforced connecting block by plug insertion .

This is not only convenient for clamping and positioning, but also more convenient for its flexible adjustment to meet the requirements of sample adjustment.

As an optimization, the upper tube middle connecting plate positioning assembly includes an upper tube middle connecting plate positioning block fixedly arranged in the middle of the upper surface of the supporting angle iron for positioning the upper tube connecting member, and the upper end of the upper tube middle connecting plate positioning block is upward Extend to form a limiting end for limiting the rear side of the connecting plate in the middle of the upper tube.

This is not only convenient for clamping and positioning, but also more convenient for its flexible adjustment to meet the requirements of sample adjustment.

As an optimization, the seat cushion support plate positioning assembly includes a seat cushion support plate positioning block fixedly arranged at the middle rear position on the upper surface of the support angle iron for positioning the upper tube connection member, and the seat cushion support plate positioning block The upper part has a positioning stepped surface for realizing the fitting and positioning of the lower surface and the front side of the seat cushion supporting plate.

This is not only convenient for clamping and positioning, but also more convenient for its flexible adjustment to meet the requirements of sample adjustment.

As an optimization, the upper tube rear connection plate positioning assembly includes a top tube rear connection plate positioning block fixedly arranged on the upper surface of the upper tube connection member positioning standard square box, and the two ends of the upper tube rear connection plate positioning block correspond to The connection hole on the rear connection plate of the upper tube is vertically set up with two positioning columns of the rear connection plate of the upper tube, and the upper end of the positioning column of the rear connection plate of the upper tube is formed with a positioning round table, which is used to insert the connection on the connection plate at the rear of the upper tube. Holes for positioning.

This is not only convenient for clamping and positioning, but also more convenient for its flexible adjustment to meet the requirements of sample adjustment.

As an optimization, the rear shock absorber installation shaft positioning assembly includes two rear shock absorber installation shaft positioning connection blocks fixedly connected to the left and right sides of the upper part of the standard square box for the upper tube connection member positioning, and the rear shock absorption installation shaft positioning The connecting block is fixed on the side of the standard square box for positioning the upper tube connecting member by bolts, and the upper surface of the connecting block for positioning the rear shock absorbing installation shaft is fixedly provided with a rear shock absorbing installation shaft positioning block. The surface is provided with a rear shock absorption installation shaft positioning groove for realizing the positioning of the rear shock absorption installation shaft. The rear shock absorption installation shaft positioning assembly also includes a rear shock absorption installation shaft compression pin, and the rear shock absorption installation shaft compression pin is vertically arranged on the The upper and lower ends of the positioning groove of the rear shock absorber installation shaft are provided with a compression block for pressing the rear shock absorber installation shaft. connection block.

This is not only convenient for clamping and positioning, but also more convenient for its flexible adjustment to meet the requirements of sample adjustment.

As an optimization, the positioning assembly for the connecting plate at the tail end of the upper tube includes a standard square box for positioning the connecting plate at the tail end of the upper tube with an overall rectangular structure, each of the standard square boxes for positioning the connecting plate at the tail end of the upper tube There are a number of installation holes arranged on the side according to the same spacing and aperture array as the installation holes on the three-dimensional installation platform. The connecting plate at the end of the upper tube is positioned with a standard square box and fixed to the upper tube connecting member on the upper surface of the three-dimensional installation platform by bolts. At the corresponding position behind the standard square box for positioning, a positioning block for the tail end of the upper tube is respectively arranged on the left and right ends of the upper surface of the standard square box for positioning the connecting plate at the tail end of the upper tube, and the positioning block at the tail end of the upper tube is outside the positioning block. A positioning step is formed for supporting and positioning the tail end of the upper pipe; the middle part of the front side of the standard square box is used for positioning the connecting plate at the tail end of the upper pipe. The upper end of the tail end connecting plate positioning block extends out of the standard square box for positioning the upper tube tail end connecting plate, and a positioning step for positioning with the front side of the upper tube tail end connecting plate is formed on the rear side. This is not only convenient for clamping and positioning, but also more convenient for its flexible adjustment to meet the requirements of sample adjustment.

The process of using the above-mentioned positioning welding fixture structure and each group of positioning components in it is as follows: first make the three positioning points on the lower part of the two half-body combinations achieve basic positioning, and then cover the reinforcing connection block on the head tube mounting bracket of the head tube assembly The front end lap of the front down tube combined with the frame half body corresponds to the position, and then the pin is inserted into the positioning hole on the positioning block of the two reinforced connecting blocks and the jack on the corresponding reinforced connecting block to realize the precise positioning of the reinforced connecting block; Lap the connecting plate in the middle of the upper tube on the middle of the two upper tubes and rely on the positioning block of the connecting plate in the middle of the upper tube to realize its front and rear positioning; rely on the positioning step surface of the positioning block of the seat cushion supporting plate to realize the positioning of the seat cushion supporting plate; The two ends of the connecting plate at the rear of the upper tube are overlapped horizontally at the corresponding positions at the rear of the two upper tubes, and then the positioning round table at the upper end of the positioning column of the connecting plate at the rear of the two upper tubes is inserted into the connecting hole on the connecting plate at the rear of the upper tube to realize alignment of the upper tube. The positioning of the rear connecting plate; the two ends of the rear shock absorber installation shaft are positioned by the rear shock absorber installation shaft positioning grooves on the upper surface of the two rear shock absorber installation shaft positioning blocks, and the rear shock absorber installation shaft is pressed against the pin. ; Rely on the positioning block at the tail end of the upper pipe to realize the auxiliary support for the tail of the two upper pipes, connect the connecting plate at the tail end of the upper pipe to the position of the tail end of the upper pipe, and then lean on the positioning step at the upper end of the positioning block at the connecting plate at the tail end of the upper pipe Achieve positioning. Then the welding and fixing of the reinforced connection block, the middle connecting plate of the upper tube, the seat cushion supporting plate, the rear connecting plate of the upper tube, the rear shock absorbing installation shaft and the connecting plate at the tail end of the upper tube can be completed by one-time welding. The mutual position accuracy of each component is reliable, and the welding operation is convenient and fast, which saves the cost. At the same time, due to the use of standard square boxes, supporting angle irons, standard anglers, three-dimensional installation platforms and other non-standard positioning components to achieve connection and cooperation, each positioning structure can be flexibly and conveniently adjusted and installed according to needs, making it very It is suitable for use when the trial production of samples needs to adjust the position of each local component, which greatly saves the cost of research and development. At the same time, some of the non-standard positioning components can realize the positioning of multiple components at the same time, and the structural arrangement is ingenious and ensures the accuracy of mutual positions.

To sum up, the utility model can simplify the welding and assembly process, has the advantages of simple operation, low cost, and convenient trial production and adjustment of the rider bike sample.

Description of drawings

Fig. 1 is a front view of a frame welding jig for a knight bike sample that adopts the structure of the utility model.

FIG. 2 is a top view of FIG. 1 .

Fig. 3 is a front view of Fig. 1 when in use.

FIG. 4 is a top view of FIG. 3 .

detailed description

The utility model will be described in further detail below in conjunction with a frame welding jig and accompanying drawings for a rider bike sample that has adopted the structure of the utility model. When the orientation description is involved in the scheme, the state after installation is taken as the orientation description benchmark.

As shown in Figures 1-4, a frame welding jig for a knight car sample, the welding jig includes a three-dimensional installation platform 1 with a number of installation holes arranged in an array at fixed intervals on the upper surface and the peripheral side surface, and is arranged on The combined positioning welding fixture structure of the head tube assembly on the three-dimensional installation platform 1, the positioning welding fixture structure of the lower part of the frame half body combination, and the positioning welding fixture structure of the upper part of the frame half body combination; the combined positioning welding fixture structure of the head tube assembly is used for To realize the positioning of the head tube assembly combination and the positioning of the direction lock block 2, the direction limit block 3, the fuel tank clamp shaft 4, the engine front suspension installation shaft 5 and the hanger 6 for installing the down inclined pipe accessories; the vehicle frame half The positioning welding fixture structure of the lower part of the body combination is used to realize the positioning of the frame half body combination, as well as the engine rear upper suspension installation shaft 7, the front lower tube strengthening connection shaft 8, the flat fork shaft 9, the engine rear lower suspension installation shaft 10 and its engine The positioning of the rear lower suspension mounting shaft lug 11, the side bracket mounting plate 12, the front lower tube transverse connecting shaft 13, the rear pedal lug 14 and the pedal mounting tube transverse connecting shaft 15; the positioning welding of the upper part of the frame half assembly The fixture structure is used to implement the reinforcement connection block 16, the upper tube middle connecting plate 17, the seat cushion supporting plate 18, the two upper tube tail ends 19, the upper tube rear connecting plate 20 and the upper tube tail end connecting plate 21 and The positioning of the rear shock absorber mounting shaft 22.

In this way, the welding jig of the above-mentioned solution can realize the clamping and positioning of the head tube assembly, the two frame halves and the auxiliary components at the same time. After positioning, the welding gun can be directly used to realize the welding between the components fixed. The mutual position accuracy of each component is reliable and the welding operation is convenient and fast, which greatly saves the cost.

Wherein, the combined positioning welding fixture structure of the head tube assembly includes a head tube positioning assembly, a direction lock block positioning assembly, a direction limit block positioning assembly, a fuel tank clamp shaft positioning assembly, an engine front suspension mounting shaft positioning assembly, and a drop tube Hanger positioning component for accessory installation;

The head tube positioning assembly includes a standard square box 23 for head tube positioning with a rectangular structure as a whole, and each side of the standard square box 23 for head tube positioning is at the same distance as the installation holes on the three-dimensional installation platform 1. And the aperture array is arranged with some mounting holes, and the standard square box 23 for head tube positioning is fixed on the front end position on the three-dimensional installation platform 1 by bolts; the standard square box 23 upper end for the head tube positioning is fixedly provided with a standard angle The standard angler 24 for the positioning of the head tube includes a fixed block and a rotating block each having a hinged end and an opening and closing end. Angle positioning rotation angle positioning pins, the fixed block and the rotating block are arranged with a number of mounting holes according to the same spacing and aperture array as the mounting holes on the three-dimensional mounting platform 1, and the head tube positioning uses the standard angler 24 The opening and closing end of the fixed block is arranged forward and fixed horizontally on the upper end of the standard square box 23 for positioning the head tube by bolts. The middle part of the upper surface of the rotating block of the standard angler 24 for positioning the head tube is fixedly provided with a round table 25 for positioning the head tube upward. The diameter of the head tube positioning round platform 25 matches the outer diameter of the lower end of the head tube and the head tube positioning round platform axis is coaxially provided with a head tube positioning column 26 matching the inner diameter of the head tube;

The direction lock block positioning assembly includes a supporting angle iron 27 for the positioning of the head tube accessories in an overall L-shaped structure, and each side of the supporting angle iron 27 for the positioning of the head tube accessories is in accordance with the mounting holes on the three-dimensional installation platform. A number of installation holes are arranged in a consistent spacing and aperture array. The lower surface of the support angle iron 27 for the positioning of the head tube accessories is attached and fixed on the upper surface of the rotating block of the standard angler for the positioning of the head tube by bolts. The support for the positioning of the head tube accessories is Angle iron 27 rear lower side upper part is fixedly provided with a direction lock block locating block 28, and direction lock block locating block 28 one ends are fixed on the rear lower side upper part of supporting angle iron for positioning of the head pipe accessories, and the other end extends to the rear lower side and at the end There are protrusions for inserting into the two grooves on the direction lock block to realize the positioning of the direction lock block 2;

The direction limiting block positioning assembly includes a supporting angle iron 27 for positioning the head tube accessories and a direction limiting block positioning block 29, and one end of the direction limiting block positioning block 29 is fixed on the rear lower side of the supporting angle iron for positioning the head tube accessories , the other end extends backward and downward and has a positioning groove at the end for inserting and abutting the lower end of the direction limiting block 3;

The fuel tank shaft positioning assembly includes a standard square box 23 for the positioning of the head tube, the upper end of the standard square box 23 for the positioning of the head tube is fixedly connected with a lower support angle iron for the positioning of the fuel tank shaft in an L-shaped structure. 30. A number of installation holes are arranged on each side of the lower support angle iron 30 for the positioning of the fuel tank shaft according to the same spacing and aperture array as the installation holes on the three-dimensional installation platform. The inner side of the lower support angle iron for the positioning of the fuel tank shaft Fitted and fixed by bolts on the outer surface of the upper end of the standard square box for the positioning of the head tube, the upper surface of the lower support angle iron 30 for the positioning of the fuel tank clamping shaft is a horizontal installation plane and is provided with an overall L-shaped structure for the positioning of the fuel tank clamping shaft Use the upper support angle iron 31, and the upper support angle iron 31 for the positioning of the fuel tank shaft is equipped with a number of installation holes on each side according to the same spacing and aperture array as the installation holes on the three-dimensional installation platform, and is fixed on the oil tank shaft by bolts. With the upper surface of the lower support angle iron, the rear side surface of the upper support angle iron 31 for positioning the fuel tank shaft is fixedly provided with a fuel tank shaft positioning block 32, and the upper surface of the fuel tank shaft positioning block 32 is horizontally provided with a The fuel tank clamping shaft positioning groove for realizing the support and positioning of the end of the fuel tank clamping shaft 4;

The engine front suspension mounting shaft positioning assembly includes a standard square box 33 for the engine front suspension mounting shaft with a rectangular body structure, and the standard square box 33 for the engine front suspension mounting shaft is in accordance with the mounting holes on the three-dimensional mounting platform 1 on each side. A number of mounting holes are arranged in a consistent spacing and aperture array. The engine front suspension mounting shaft is fixed to the corresponding position behind the standard square box on the three-dimensional installation platform with bolts, and the engine front suspension mounting shaft is fixed to the corresponding position behind the standard square box. The width of 33 is consistent with the diameter of the lower inclined pipe in the combination of the head tube assembly. The standard square box 33 is used for the installation shaft of the front suspension of the engine. The positioning block 34 has a part that extends forward out of the standard square box for the engine front suspension installation shaft, and on this part, two engine front suspension installation holes corresponding to the engine front suspension installation shaft installation holes on the lower inclined tube are arranged obliquely. The shaft positioning hole is used for the insertion and positioning of the engine front suspension installation shaft 5;

The hanger positioning assembly for installing the accessories of the lower inclined pipe includes a standard square box 33 for the installation shaft of the front suspension of the engine. Frame positioning block 35, the front end of the hanger positioning block 35 for the installation of the descending pipe accessories is extended obliquely upwards to form a hanger positioning end for the installation of the descending pipe accessories, the shape of the front side of the hanger positioning end for the installation of the descending pipe accessories It is consistent with the shape of the rear lower surface of the hanger 6 for installing the accessories of the descending pipe and is used to realize the support and positioning of the lower surface of the hanger 6 for installing the accessories of the descending pipe.

In this way, when in use, first adjust the angle of the head tube positioning standard angler to the required angle, and then insert the head tube into the head tube positioning column so that the lower end and the head tube positioning round table abut and support and realize The positioning of the head tube, and then make the lower end of the down slope tube fall between the two engine front suspension installation shaft positioning blocks, and insert the two engine front suspension installation shafts transversely into the corresponding engine front suspension installation shaft positioning holes and the engine front suspension. Suspension mounting shaft mounting hole; in this way, it realizes the positioning of the front suspension mounting shaft of the root engine, and at the same time realizes the complete positioning of the head tube assembly; then attach the direction lock block to the installation position of the upper end of the head tube And rely on the protrusions at the front end of the direction lock block positioning block to insert into the two grooves of the direction lock block to realize the positioning of the direction lock block; attach the upper end of the direction limit block to the installation position of the lower end of the head tube and insert the lower end into abutment In the positioning groove of the positioning block of the direction limiting block, realize the positioning of the direction limiting block; then insert the fuel tank clamping shaft horizontally into the mounting hole on the head tube mounting frame, and position and support the two ends to the fuel tank clamping shaft Position the fuel tank clamp shaft in the fuel tank clamp shaft positioning groove on the upper surface of the positioning block; The upper front end of the hanger positioning block for installing the inclined pipe accessories is fitted and abutted against the support, so as to realize the positioning of the hanger for installing the inclined pipe accessories. In this way, the welding torch can be used to realize the welding between the head tube assembly and the engine front suspension installation shaft, direction lock block, direction limit block, fuel tank clamp shaft and drop tube attachment hanger at one time. fixed. The mutual position accuracy of each component is reliable, and the welding operation is convenient and fast, which saves the cost. At the same time, due to the use of standard square boxes, supporting angle irons, standard anglers, three-dimensional installation platforms and other non-standard positioning components to achieve connection and cooperation, each positioning structure can be flexibly and conveniently adjusted and installed according to needs, making it very It is suitable for use when trial production of samples needs to adjust the position of local components of each component, which greatly saves the cost of research and development. At the same time, some of the non-standard positioning components can realize the positioning of multiple components at the same time, and the structural arrangement is ingenious and ensures the accuracy of mutual positions.

Wherein, the positioning welding fixture structure of the lower part of the frame half body assembly includes the engine rear upper suspension installation shaft and the front lower tube reinforced connection shaft positioning assembly, the flat fork shaft and the engine rear lower suspension installation shaft positioning assembly, and the front lower tube transverse connection shaft Positioning component, side bracket mounting plate positioning component, rear pedal lug positioning component and pedal mounting tube transverse connection shaft positioning component;

The engine rear upper suspension installation shaft and the front lower tube reinforced connection shaft positioning assembly include a standard square box 36 for positioning the front lower tube accessory components with a rectangular structure as a whole, and the standard square box 36 for positioning the front lower tube accessory components A number of installation holes are arranged on each side according to the same spacing and aperture array as the installation holes on the three-dimensional installation platform 1, and the standard square box 36 for the positioning of the auxiliary components of the front down tube is fixed on the three-dimensional installation platform by bolts and is located on the front suspension installation of the engine. The corresponding position at the rear of the standard square box 33 for the shaft; the left and right sides of the standard square box 36 top for the positioning of the front lower tube accessory components are fixedly connected by bolts to a rear upper suspension installation shaft of the engine and a front lower tube reinforced connection shaft positioning block 37, The rear upper suspension installation shaft of the engine and the front lower tube reinforced connection shaft positioning block 37 have a rear end extending rearward and upward, and a front lower tube reinforced connection for positioning the front lower tube reinforced connection shaft 8 is provided upwards on the upper end. Shaft positioning groove 38, the engine rear upper suspension installation shaft and the middle part of the front lower tube reinforced connection shaft positioning block are correspondingly provided with the engine rear upper suspension installation shaft positioning hole 39 and are used for inserting the end of the engine rear upper suspension installation shaft 7 achieve positioning;

The horizontal fork shaft and the engine rear lower suspension mounting shaft positioning assembly include a standard square box 36 for the positioning of the accessory components of the front down tube, and also include a vertical box at the middle of the left and right sides of the standard square box for the positioning of the accessory components of the front down tube by bolts. To the flat fork shaft positioning block 40 provided, the rear upper end position of the flat fork shaft positioning block 40 is correspondingly provided with a flat fork shaft positioning hole 41 for the flat fork shaft to penetrate and locate; the rear lower side of the flat fork shaft positioning block The central portion extends downwards to form a positioning block 42 for the mounting shaft of the rear suspension of the engine. Positioning hole for mounting shaft of rear lower suspension;

The front lower tube transverse connecting shaft positioning assembly includes a standard square box 36 for positioning the accessory components of the front down tube, and also includes vertically arranged front boxes 36 fixed to the lower parts of the left and right sides of the standard square box for positioning the accessory components of the front down tube by bolts. The lower tube lateral connection shaft positioning block 43, the front lower tube lateral connection shaft positioning block 43 is extended to the rear and upper direction, and the rear upper end surface is correspondingly provided with the front lower tube lateral connection for realizing the support and positioning of the front lower tube lateral connection shaft 13 Shaft positioning groove 44;

The side bracket mounting plate positioning assembly includes a standard square box 45 for the positioning of the side bracket mounting plate with a rectangular structure as a whole, and each side of the standard square box 45 for the positioning of the side bracket mounting plate is in accordance with the three-dimensional installation platform. There are several installation holes arranged in the same spacing and aperture array of the installation holes, and the standard square box 45 used for positioning the side bracket installation plate is fixed on the three-dimensional installation platform 1 by bolts and is located at the corresponding position behind the standard square box 36 used for positioning the accessory components of the front lower tube; The left and right sides of the standard square box 45 top for bracket mounting plate positioning are respectively fixedly connected with a side support mounting plate positioning block 46 by bolts, and the front end of the side support mounting plate positioning block extends forward and downward and is provided with for realizing on the outer upper side of the front end. The side bracket mounting plate positioning step 47 is embedded in the lower side of the side bracket mounting plate, and is provided with a positioning hole consistent with the connecting hole on the side bracket mounting plate and used for insertion and positioning by the latch on the step surface;

The rear pedal lug positioning assembly includes two standard square boxes 48 for positioning the rear pedal lugs with a rectangular structure as a whole, and each side of the standard square box 48 for positioning the rear pedal lugs is in accordance with the three-dimensional installation platform. There are several mounting holes arranged in an array of consistent spacing and apertures on the mounting holes. The standard square box 48 used for the positioning of the two rear pedal lugs is fixed on the three-dimensional mounting platform by bolts and located on the left and right sides of the standard square box 45 used for positioning the side bracket mounting plate. The rear corresponding position; the standard square box 48 for the positioning of the rear pedal lugs is also fixedly provided with a standard angler 49 for the positioning of the rear pedal lugs, and the standard angler 49 for the positioning of the rear pedal lugs includes a hinged end and a A fixed block and a rotating block at the opening and closing end, the hinged ends of the fixed block and the rotating block can be rotatably hinged and a rotating angle positioning pin for realizing the positioning of the rotating angle is arranged at the hinge, and the fixed block and the rotating block are in accordance with the three-dimensional The mounting holes on the installation platform are arranged with a number of mounting holes at the same spacing and aperture array, and the opening and closing ends of the fixed block of the standard angler 49 are arranged backwards for the positioning of the rear pedal lugs and are horizontally fixed on the rear pedal lugs for positioning by bolts. With the upper end of the standard square box 48, the middle part of the upper surface of the rotating block of the standard angler 49 for the positioning of the rear pedal lugs is fixedly provided with a rear pedal lug positioning block 50 for realizing the rear lower side support positioning of the rear pedal lugs. The installation holes on the correspondingly positioned rear pedal lugs on the lug positioning block 50 are provided with jacks and latches for locking the rear pedal lugs 14 after positioning;

The positioning assembly for the lateral connection shaft of the pedal installation tube includes two standard square boxes 51 for the positioning of the lateral connection shaft of the pedal installation tube in a rectangular structure as a whole, and each side of the standard square box 51 for the lateral connection shaft of the pedal installation tube A number of installation holes are arranged on the upper part according to the same spacing and aperture array as the installation holes on the three-dimensional installation platform 1, and the standard square box 51 is fixed on the three-dimensional installation platform 1 by bolts for the positioning of the lateral connecting shaft of the pedal installation pipe and is located on the rear pedal. The standard square box 48 rear inner position is used for lug positioning; the standard square box 51 outer surface of the two pedal installation tubes is used for positioning the horizontal connection shaft. The front upper end of the pedal installation pipe transverse connection shaft positioning block 52 extends out of the standard square box for positioning the pedal installation pipe transverse connection shaft, and the end is correspondingly provided with feet for inserting and positioning the pedal installation pipe transverse connection shaft 15 Pedal installation tube connects the axis positioning hole horizontally.

In this way, when in use, the two frame halves are arranged side by side, so that the upper end of the front lower tube overlaps the corresponding position on the already positioned head tube combination and the two parts are determined by the covered reinforced connection block. The left and right position of the upper end of the front lower tube, and then the combination of the two frame halves first realizes the penetrating positioning of the flat fork shaft installation, the supporting positioning of the transverse connecting shaft of the front down tube, and the penetrating positioning of the transverse connecting shaft of the pedal installation tube, and relies on the The three positioning points of the triangle formed in this way realize the positioning of the two frame halves at the same time; then rely on the rear upper suspension installation shaft of the engine and the front lower tube to strengthen the connection shaft and the front lower tube at the rear upper end of the positioning block to strengthen the connection The shaft positioning groove supports the reinforced connection shaft of the front lower tube, and at the same time makes the pre-fixed two ends of the reinforced connection shaft of the front lower tube adhere to the surface of the corresponding connection position on the front lower tube. At the same time, the positioning of the reinforced connecting shaft of the front lower tube and the reinforced connecting shaft of the front lower tube is realized; and then the two ends of the installed shaft lugs of the upper rear suspension of the engine which have been connected and fixed in advance are inserted into the upper rear suspension of the engine for installation. In the shaft positioning hole, rotate and adjust the engine rear upper suspension installation shaft so that the engine rear upper suspension installation shaft lugs and the corresponding installation positions of the front lower tube fit together, so that the engine rear upper suspension installation shaft and the engine rear upper suspension installation shaft can be realized at the same time Positioning of the lugs; then insert the two ends of the engine rear suspension installation shaft pre-connected and fixed with the engine rear suspension installation shaft lugs into the engine rear suspension installation shaft positioning holes on the engine rear suspension installation shaft positioning block, Then make the engine rear lower suspension installation shaft lug fit with the corresponding position on the front lower tube, that is, the positioning of the engine rear lower suspension installation shaft and the engine rear lower suspension installation shaft lug is realized at the same time; then install the side bracket behind the plate The lower side is fitted and positioned on the side bracket mounting plate positioning step of the side bracket mounting plate positioning block, so that the upper end side and the upper connection position of the front down tube fit to achieve positioning, and then insert the pin into the connecting hole on the side bracket mounting plate and The positioning hole on the positioning step of the side bracket mounting plate is locked; then the rear pedal lug is positioned on the rear pedal lug positioning block and locked by the latch. Like this, just can adopt welding torch one-time to realize the welding fixing of each accessory component of two vehicle frame halves combined lower parts. The mutual position accuracy of each component is reliable, and the welding operation is convenient and fast, which saves the cost. At the same time, due to the use of standard square boxes, supporting angle irons, standard anglers, three-dimensional installation platforms and other non-standard positioning components to achieve connection and cooperation, each positioning structure can be flexibly and conveniently adjusted and installed according to needs, making it very It is suitable for use when the trial production of samples needs to adjust the position of each local component, which greatly saves the cost of research and development. At the same time, some of the non-standard positioning components can realize the positioning of multiple components at the same time, and the structural arrangement is ingenious and ensures the accuracy of mutual positions.

Wherein, the upper positioning welding fixture structure of the frame half body assembly includes a reinforcing connection block positioning component, a connecting plate positioning component in the middle of the upper tube, a seat cushion supporting plate positioning component, a rear connecting plate positioning component of the upper tube, and a rear shock absorbing installation. Shaft positioning assembly and connecting plate positioning assembly at the tail end of the upper tube;

The reinforcing connection block positioning assembly includes a standard square box 53 for positioning the upper tube connecting member with a rectangular structure as a whole, and each side of the standard square box 53 for positioning the upper tube connecting member is installed according to the installation on the three-dimensional installation platform. There are a number of mounting holes arranged in an array with consistent spacing and apertures. The standard square box 53 used for the positioning of the upper pipe connecting member is fixed on the corresponding position on the upper and rear of the three-dimensional installation platform 1 by bolts. The upper front side of the upper part of the standard square box 53 is used for positioning the upper pipe connecting member A support angle iron 54 for the positioning of the upper pipe connecting member that is triangular as a whole is fixedly arranged, and each side of the supporting angle iron 54 for the positioning of the upper pipe connecting member is arrayed according to the same spacing and aperture as the installation holes on the three-dimensional installation platform. A number of installation holes are arranged, and the supporting angle iron 54 for the positioning of the upper tube connecting member has a vertical connecting surface that is vertically attached to the front side of the standard square box for the positioning of the upper tube connecting member and is fixedly connected by bolts. The upper surface of the supporting angle iron 54 for positioning the connecting member is an installation plane extending horizontally forward; The reinforcing connection block locating block 55 that direction is vertically arranged at intervals, the spacing between two reinforcing connecting block locating blocks 55 is greater than the width of reinforcing connecting block 16 and the jack on the corresponding reinforcing connecting block 16 of two reinforcing connecting block upper ends is provided with for relying on Insert the pin into the positioning hole to realize the positioning of the reinforced connection block 16;

The upper tube middle connecting plate positioning assembly includes an upper tube middle connecting plate positioning block 56 fixedly arranged on the middle of the upper surface of the upper tube connecting member positioning support angle iron 54, and the upper end of the upper tube middle connecting plate positioning block 56 is upward extending to form a limiting end for limiting the rear side of the connecting plate 17 in the middle of the upper pipe;

The seat cushion supporting plate positioning assembly includes a seat cushion supporting plate positioning block 57 fixedly arranged on the upper surface of the upper surface of the support angle iron 54 for the upper tube connecting member positioning block 57, the seat cushion supporting plate positioning block 57 The upper part has a positioning step surface for realizing the positioning of the lower surface and the front side of the seat cushion supporting plate 18;

The upper tube rear connecting plate positioning assembly includes an upper tube rear connecting plate positioning block 58 fixedly arranged on the upper surface of the upper tube connecting member positioning standard square box, and the two ends of the upper tube rear connecting plate positioning block 58 correspond to the upper The connecting hole on the tube rear connecting plate is vertically provided with two upper tube rear connecting plate positioning columns 59, and the upper end of the upper tube rear connecting plate positioning column 59 is formed with a positioning round platform 60 for inserting the upper tube rear connecting plate 20 The connection hole on the top realizes the positioning;

The rear shock absorber installation shaft positioning assembly includes two rear shock absorber installation shaft positioning connection blocks 61 fixedly connected to the upper left and right sides of the upper tube connection member positioning standard square box 53, and the rear shock absorber installation shaft positioning. The connecting block 61 is fixed on the side of the standard square box 53 for the positioning of the upper tube connecting member by bolts, and the upper surface of the connecting block 61 for positioning the rear shock absorbing installation shaft is fixedly provided with a rear shock absorbing installation shaft positioning block 62, and the rear shock absorbing installation shaft The upper surface of the positioning block 62 is provided with a rear shock absorption installation shaft positioning groove for realizing the positioning of the rear shock absorption installation shaft. The pin 63 is vertically arranged above the positioning groove of the rear shock absorber installation shaft and the lower end is provided with a compression block for compressing the rear shock absorber installation shaft. The rear shock absorber installation shaft compression pin 63 is installed through the installation bracket 64 On the connecting block 61 for the positioning of the rear shock absorber installation shaft;

The positioning assembly of the connecting plate at the tail end of the upper tube includes a standard square box 65 for positioning the connecting plate at the tail end of the upper tube with an overall rectangular structure, and each side of the standard square box 65 for positioning the connecting plate at the tail end of the upper tube A number of installation holes are arranged on the upper surface according to the same spacing and aperture array as the installation holes on the three-dimensional installation platform 1, and the upper pipe on the upper surface of the three-dimensional installation platform 1 is fixed by bolts with a standard square box 65 for the positioning of the connecting plate at the end of the upper pipe. The corresponding position behind the standard square box 53 for positioning the connecting member, the standard square box 65 for positioning the connecting plate at the tail end of the upper pipe is respectively provided with a positioning block 66 at the left and right ends of the upper surface of the tail end of the upper pipe. The outer side of the end positioning block 66 is formed with a positioning step 67 for supporting and positioning the tail end of the upper pipe; the connecting plate at the tail end of the upper pipe is positioned at the middle of the front side of the standard square box and is fixedly provided with an upper pipe tail end The connecting plate positioning block 68, the upper end of the upper pipe tail end connecting plate positioning block 68 extends out of the upper pipe tail end connecting plate positioning standard square box 65 and is formed on the rear side for connecting with the upper pipe tail end connecting plate 21 front side Locating steps for snug positioning.

In this way, when in use, first make the three positioning points on the lower part of the two half-body combinations realize the basic positioning, and then cover the head tube mounting frame of the head tube assembly with the reinforcing connection block and the front end of the front lower tube of the frame half-body combination. Then insert the pins into the positioning holes on the positioning blocks of the two reinforced connection blocks and the sockets on the corresponding reinforced connection blocks to realize the precise positioning of the reinforced connection blocks; lap the connecting plate in the middle of the upper tube on the two upper tubes The middle part and the positioning block of the connecting plate in the middle of the upper tube realize its front and rear positioning; the positioning of the seat cushion supporting plate is realized by the positioning step surface of the positioning block of the seat cushion supporting plate; The corresponding positions at the rear of the two upper tubes, and the positioning of the rear connecting plate of the upper tube is realized by inserting the positioning round table at the upper end of the positioning column of the connecting plate at the rear of the two upper tubes into the connecting hole on the connecting plate at the rear of the upper tube; The rear shock absorption installation shaft positioning groove on the upper surface of the shock absorption installation shaft positioning block realizes the positioning of both ends of the rear shock absorption installation shaft, and presses against the compression pin of the rear shock absorption installation shaft; Based on the auxiliary support at the tail of the upper tube, the connecting plate at the tail end of the upper tube is lapped at the tail end of the upper tube, and then the positioning is realized by the positioning step at the upper end of the positioning block of the connecting plate at the tail end of the upper tube. Then the welding and fixing of the reinforced connection block, the middle connecting plate of the upper tube, the seat cushion supporting plate, the rear connecting plate of the upper tube, the rear shock absorbing installation shaft and the connecting plate at the tail end of the upper tube can be completed by one-time welding. The mutual position accuracy of each component is reliable, and the welding operation is convenient and fast, which saves the cost. At the same time, due to the use of standard square boxes, supporting angle irons, standard anglers, three-dimensional installation platforms and other non-standard positioning components to achieve connection and cooperation, each positioning structure can be flexibly and conveniently adjusted and installed according to needs, making it very It is suitable for use when the trial production of samples needs to adjust the position of each local component, which greatly saves the cost of research and development. At the same time, some of the non-standard positioning components can realize the positioning of multiple components at the same time, and the structural arrangement is ingenious and ensures the accuracy of mutual positions.

Claims (7)

1. A frame half-body combined upper part positioning welding fixture structure for a knight car sample, characterized in that it includes a strengthening connection block positioning assembly for realizing the positioning of the strengthening connection block, an upper part for realizing the positioning of the connecting plate in the middle of the upper tube Tube middle connection plate positioning assembly, seat cushion support plate positioning assembly for positioning seat cushion support plate, upper tube rear connection plate positioning assembly for upper tube rear connection plate positioning, rear reducer The rear shock absorber mounting shaft positioning assembly for positioning the shock mounting shaft and the upper tube tail end connecting plate positioning assembly for positioning the upper tube tail end connecting plate. 2. The frame half assembly upper positioning welding jig structure for the rider bike sample according to claim 1, characterized in that, the reinforcing connection block positioning assembly includes an overall rectangular body structure for the positioning of the upper tube connecting member. Standard square box, on each side of the standard square box for the positioning of the upper pipe connecting member, several mounting holes are arranged according to the same spacing and aperture array as the mounting holes on the three-dimensional installation platform, and the standard square box for the positioning of the upper pipe connecting member The bolts are fixed on the corresponding position on the rear part of the three-dimensional installation platform, and the upper front side of the standard square box for the positioning of the upper tube connecting member is fixedly provided with a triangular supporting angle iron for the positioning of the upper tube connecting member. There are a number of installation holes on each side of the support angle iron according to the same spacing and aperture array as the installation holes on the three-dimensional installation platform. The vertical connection surface on the front side of the standard square box is fixed and connected by bolts, and the upper surface of the support angle iron for the positioning of the upper pipe connection member is an installation plane extending horizontally forward; The positioning of the upper pipe connection member is supported by two reinforced connection block positioning blocks vertically spaced along the left and right directions in the middle of the front end of the upper surface of the supporting angle iron. The distance between the two reinforced connection block positioning blocks is greater than the width of the reinforced connection block and the two reinforced connection blocks The upper end of the connection block corresponds to the jack on the reinforced connection block, and a positioning hole is provided for positioning the reinforced connection block by insertion of a latch. 3. The frame half assembly upper positioning welding jig structure for the rider bike sample according to claim 1, characterized in that, the positioning assembly of the connecting plate in the middle of the upper tube includes a support angle fixedly arranged on the upper tube connecting member for positioning. An upper tube middle connecting plate positioning block at the middle of the iron upper surface, the upper end of the upper tube middle connecting plate positioning block extends upwards to form a limiting end for limiting the rear side of the upper tube middle connecting plate. 4. The frame half assembly upper positioning welding fixture structure for the rider bike sample according to claim 1, characterized in that, the seat cushion supporting plate positioning assembly includes a support angle fixedly arranged on the upper tube connecting member positioning. A seat cushion support plate positioning block at the middle and rear position of the iron upper surface, the upper part of the seat cushion support plate positioning block has a positioning step surface for realizing the fitting and positioning of the seat cushion support plate lower surface and the front side . 5. The frame half assembly upper positioning welding fixture structure for the rider bike sample according to claim 1, characterized in that, the positioning assembly of the connecting plate at the rear part of the upper tube includes a standard for positioning the connecting member fixedly arranged on the upper tube. A positioning block for the rear connection plate of the upper tube on the upper surface of the square box, the two ends of the positioning block of the rear connection plate of the upper tube correspond to the connection holes on the rear connection plate of the upper tube, and two positioning columns of the rear connection plate of the upper tube are arranged vertically upward , the upper end of the positioning column of the connecting plate at the rear of the upper tube is formed with a positioning round platform and is used for inserting into the connecting hole on the connecting plate at the rear of the upper tube to realize positioning. 6. The frame half assembly upper positioning welding jig structure for the rider bike sample according to claim 1, characterized in that, the rear shock absorber mounting shaft positioning assembly includes a standard square fixedly connected to the upper tube connecting member positioning. Two connecting blocks for positioning the rear shock absorbing installation shaft on the left and right sides of the upper part of the box, the connecting blocks for positioning the rear shock absorbing installation shaft are fixed on the side of the standard square box for positioning the upper tube connecting member by bolts, and the positioning of the rear shock absorbing installation shaft The upper surface of the connecting block is fixedly provided with a rear shock absorber installation shaft positioning block, and the upper surface of the rear shock absorber installation shaft positioning block is provided with a rear shock absorber installation shaft positioning groove for realizing the positioning of the rear shock absorber installation shaft. The shaft positioning assembly also includes a rear shock absorber installation shaft compression pin, the rear shock absorption installation shaft compression pin is vertically arranged above the rear shock absorption installation shaft positioning groove and the lower end is provided with a compression block for realizing alignment of the rear shock absorption installation shaft. The compression of the rear shock absorber installation shaft is installed on the connection block for positioning the rear shock absorber installation shaft through the installation bracket. 7. The frame half assembly upper positioning welding fixture structure for the rider bike sample according to claim 1, characterized in that, the positioning assembly of the connecting plate at the tail end of the upper tube includes an upper tube with a rectangular structure as a whole A standard square box for positioning the connecting plate at the tail end, and a number of mounting holes are arranged on each side of the standard square box for positioning the connecting plate at the tail end of the upper pipe according to the same spacing and aperture array as the mounting holes on the three-dimensional mounting platform, The standard square box for positioning the connecting plate at the tail end of the upper tube is fixed by bolts to the corresponding position behind the standard square box for positioning the connecting member at the upper surface of the three-dimensional installation platform. The left and right ends of the surface are each provided with a positioning block for the tail end of the upper tube, and a positioning step for supporting and positioning the tail end of the upper tube is formed on the outside of the positioning block for the tail end of the upper tube; the tail end of the upper tube is connected to The middle part of the front side of the standard square box for plate positioning is fixedly equipped with a positioning block for the connecting plate at the tail end of the upper tube. The rear side is formed with a positioning step for fitting and positioning with the front side of the connecting plate at the tail end of the upper pipe.