Introduce in detail: What is the design process of automobile checking fixture?

Complete standard design process of automobile inspection fixture (universal sunroof/interior/exterior version)

First, the preliminary data reception and review (project stage)

Receive a complete set of design data

Product 3D digital-analog (CATIA/UG/STEP), 2D engineering drawings, GD&T shape and position tolerance drawings.

Product RPS benchmark drawings (the core, the unified benchmark of the car body)

Product material thickness, material, stamping/injection molding/foaming process, batch capacity

Standard of customer's fixture: standards of automobile enterprises (SAIC/Geely/BYD/Volkswagen, etc.), fixture grade and accuracy requirements.

List of inspection items: appearance, outline, hole position, trimming, clearance, assembly matching, buckle position, etc.

Data review

Check the size consistency between digital model and 2D diagram.

Confirm the primary and secondary reference, detection direction and interference area.

Determine the easily deformable area of the product, and plan the positioning and compaction scheme in advance.

Determine the fixture type: fixed fixture, turnover fixture, sliding fixture and assembly fixture.

Second, the scheme planning and layout design (first draft stage)

Determine the 3-2-1 positioning scheme

3 principal datum planes (limited to 3 degrees of freedom)

2 round locating pins (limited to 2 degrees of freedom)

1 diamond-shaped anti-rotation pin (limit the last one degree of freedom)

Strictly align the RPS coordinate system of the whole vehicle, and do not change the benchmark without permission.

Compaction mechanism layout

The clamping point is away from the product appearance surface, sealing surface and assembly surface.

Quick clamping, pneumatic clamping and vertical pressing clamping are preferred.

An auxiliary support (jacking block) is added to the deformable part.

Detection structure planning

Contour detection: the profile block is shrunk by 3~5mm, and the clearance is detected with a feeler gauge.

Hole position detection: on-off detection pin and floating detection pin.

Edge cutting/flanging: thickness gauge, flush template

Installation buckle/slot: special profiling card plate

Large size: equipped with dial indicator and height gauge measuring base.

Overall layout of checking fixture

Determine the size and operating height of the bottom plate (standard 850mm)

Reserve picking space and operator activity space.

Plan the positions of handles, nameplates, datum marks and station numbers.

Output the Design Scheme of Checking Fixture.

2D Layout Sketch+3D Layout Draft

Positioning and compaction description, detection method, material selection and accuracy grade

Send the scheme to the customer for confirmation and signature, and then enter the detailed design without error.

Three-dimensional detailed structural design (core design stage)

Floor system design

Material: cast aluminum/welded steel plate/HT250 cast iron

Machining datum grooves, datum holes, lifting holes, foot cups and casters.

Reinforce ribs to prevent deformation after long-term use.

Design of positioning support assembly

Reference support block, spherical support and adjustable support column

Complete structure of locating pin seat, pin sleeve, foolproof pin and diamond pin

All positioning parts are made of wear-resistant and hardened structures.

Profile design of copying detection

Make detection surface and yield surface according to product digital-analog deviation.

Sharp corner rounding, void avoidance chamfering, and motion avoidance

The long profile is provided with telescopic anti-deformation joints.

Split design of parting surface and block (convenient for processing and mold repair)

Complete modeling of clamping mechanism

Clamp base, pressure head, pressure head rubber head and limit block.

Pneumatic inspection tools: layout of cylinders, gas pipelines, switches and pressure regulating valves.

Auxiliary function design

Product error-proof structure, positive and negative foolproof

Detection pin storage seat and feeler gauge storage position

Datum coordinate scribed line and zero datum mark

Dust-proof and simple protective structure

Standard parts selection and warehousing

Clamps, guide posts, guide sleeves, screw pins, handles, and rulers all use general standard parts for automobile inspection tools.

3D assembly self-inspection

Full-stroke interference inspection

Check the smoothness of product taking and placing.

Check whether the clamping force crushes the product.

Check whether the space is sufficient.

Four, two-dimensional engineering drawing and BOM list

Split all parts into 2D machining drawings.

Bottom plate, profile block, positioning block, pressing block, detection pin seat, etc.

Mark the form and position tolerance, machining tolerance, surface roughness and heat treatment requirements.

Mark the tolerance of key fixture.

Reference position: ≤0.02mm

Profile of profile: ≤0.03~0.05mm

Measuring pin position: ≤ 0.03mm.

Flatness of bottom plate: ≤0.1mm/1000mm.

Prepare a complete BOM bill of materials

Part name, drawing number, material, quantity, heat treatment and surface treatment

List of standard parts and purchased parts

Drawing review, proofreading and standardized signature

Designer self-inspection → team leader review → process review → distribution of production.

Five, process planning and production and processing stage

Work out the processing route

Blanking → Roughing → Stress Relief and Aging → Finishing → Hole Processing → Surface Treatment.

Machining of main parts

Bottom plate: rough and fine milling with gantry milling and boring with reference hole.

Aluminum profile: five-axis linkage milling profile

Steel wear-resistant parts: CNC machining+heat treatment quenching

Precision parts processing

Locating pin and detecting pin: grinding machine finishing and slow wire cutting.

Pin sleeve and guide sleeve: fine grinding of inner and outer circles.

surface treatment

Aluminum parts: hard anodic oxidation

Steel parts: quenched and tempered, hard chromium plated, blackened and rustproof.

Check the working face for wear resistance treatment.

VI. Assembly, research and debugging of inspection tools

Pre-assembled fittings

Base plate is pre-installed with reference base and support base.

Profile blocks are assembled and pre-assembled, and the mating surfaces are ground.

Precision matching and research

The datum plane shall be scraped and leveled to ensure the fit clearance.

The locating pin is equipped with hinge holes to ensure smooth plugging and unplugging without looseness.

Fine adjustment of clamp stroke and uniform compaction height

Debugging of motion mechanism

The turnover mechanism and sliding mechanism have smooth debugging and accurate limit.

Pneumatic circuit debugging: pressure stabilization and clamping synchronization.

Appearance finishing

Deburring, chamfering the safety angle, and painting color separation (reference surface/detection surface/base color separation)

Marking lines, numbering, and attaching nameplates.

Seven, three coordinate accuracy detection and verification (factory)

Establish a fixture coordinate system

Establishing the consistent coordinate system of the whole vehicle according to RPS benchmark

Full-scale accuracy detection

All datum coordinates are re-measured.

Collection of product profile inspection points

Position detection of all locating pins and mounting holes

Key matching size and clearance surface detection

Issue a three-coordinate test report

Repeatability verification GRR test

Multi-person multi-clamping inspection verifies the stability of the fixture.

Repair and correction of unqualified items

Grinding, milling, fine-tuning and correction of deviation out-of-tolerance parts

VIII. Trial Production Verification and Customer Acceptance

On-board product real vehicle/real piece trial assembly inspection

Put in qualified products and simulate the whole process of on-site inspection.

Verify that the whole process of picking, placing, clamping, testing and pin removal is smooth.

Verify whether the matching gap and assembly error meet the requirements of mass production.

Organize a complete set of acceptance data

3D digital-analog and 2D complete sets of drawings

BOM list, heat treatment report, material report

Three-coordinate test report, GRR report

Instruction manual and maintenance manual for checking fixture.

Customer site acceptance

On-site accuracy retest and operation demonstration

The customer signs to confirm the acceptance.

IX. Delivery and warehousing+after-sales technical disclosure

Packaging, delivery and protective treatment

On-site installation leveling and leveling

Operator training: clamping method, detection method and daily maintenance.

Handover of later maintenance drawings and spare parts drawings.

Minimalist flow shorthand

Data receiving →RPS benchmarking scheme →3D structural design → 2D drawing BOM→ machining → assembly and research → three-coordinate calibration → sample test → customer acceptance → delivery training.