Technical requirements for mechanical design

1、 Stamping parts

1. Sharp edge deburring, stamping notch roughness 6.3

2. Punch surface oxidation treatment: H.Y. or (galvanized dull color on the surface. Zn8. DC.)

3. The limit deviation of dimensions without tolerance indications shall be in accordance with GB/T 1804-92 m level

2、 Castings

1. The casting shall be free of defects such as air hole, slag inclusion and crack.

2. Unspecified casting slope is 1-2.5%% d.

3. The casting tolerance shall comply with GB6414-86CT6

4. Unspecified casting fillet is R1-R2.5.

5. The limit deviation of dimensions without tolerance indications shall be in accordance with GB/T 1804-92 m level

6. Undeclared geometric tolerance shall comply with GB/T1184-96 Grade H

7. Deburring, unmarked chamfer 0.5×45 °

3、 Forgings

1. Undeclared forging fillet radius is R1~R2

2. Undeclared forging slope is 1~1.5 °, and forging tolerance is IT15

3. The forging shall be compact in structure, free of defects such as folds and cracks, and free of flash

4. Remove sharp edges and burrs, and blunt right angles

5. The limit deviation of dimensions without tolerance indications shall be in accordance with GB/T 1804-92 m level

6. Undeclared geometric tolerance shall comply with GB/T1184-96 Grade H

4、 Piston parts

1. The limit deviation of dimensions without tolerance indications shall be in accordance with GB/T 1804-92 m level

2. Undeclared geometric tolerance shall comply with GB/T1184-96 Grade H

3. Deburr and unmarked chamfer 0.5×45 °

4. Surface phosphating treatment

5、 Rubber parts

1. The surface of the part shall be smooth and clean (the surface roughness of the die shall be above Ra0.4), and no bubble, impurity level convex concave and other defects are allowed

2. The mold closing seam shall not be dislocated, and the thickness of the convex level of the mold closing flash shall not be greater than 0.02mm

3. Shore A hardness 65%% P5

4. Remove the flash

6、 Plastic parts

1. Materials shall be preheated and dried before forming

2. After forming, the parts shall be smooth and free of distortion

3. Undeclared fillet is R0.5

4. The external surface shall be smooth, with roughness not greater than Ra0.4. There shall be no scratch, nick and other defects

5. Undeclared dimensional tolerance shall conform to GB/T 1804-92 m level

7、 Spring piece

1. Rotation direction: left rotation

2. Total number of turns: no=12

3. Number of working cycles: no=10

4. Steel wire hardness: HRC42~48

5. Surface oxidation treatment: H.Y. (commonly known as blackening)

6. Single end parallel grinding

8、 To sum up, there are the following basic technical requirements for reference (specific values and terms shall be determined by the designer according to the actual situation):

1. General technical requirements:

L Remove oxide scale from parts.

L There shall be no scratch, scratch and other defects that damage the part surface on the part processing surface.

L Remove burrs and fins.

2. Heat treatment requirements:

L After quenching and tempering, HRC50~55.

L Parts shall be subject to high-frequency quenching, 350~370 ℃ tempering and HRC40~45.

L Carburizing depth 0.3mm.

L Carry out high temperature aging treatment.

3. Tolerance requirements:

L Undeclared shape tolerance shall meet the requirements of GB1184-80.

L The allowable deviation of unspecified length dimension is ± 0.5mm.

L The casting tolerance zone is symmetrical to the basic dimension configuration of the blank casting.

4. Part edges and corners:

L Undeclared fillet radius R5.

L Undeclared chamfers are all 2 × 45°。

L Sharp corner rounding off.

5. Assembly requirements:

L All seals must be soaked with oil before assembly.

L It is allowed to heat the assembled rolling bearing with oil, and the oil temperature shall not exceed 100 ℃.

L After the gearbox is assembled, the no-load test shall be carried out according to the design and process regulations. During the test, there shall be no impact and noise, and the temperature rise and leakage shall not exceed the provisions of relevant standards.

L After the gear is assembled, the contact pattern and backlash of the gear surface shall comply with the provisions of GB10095 and GB11365.

L It is allowed to use sealing filler or sealant when assembling the hydraulic system, but it should be prevented from entering the system.

L The parts and components (including purchased parts and outsourced parts) to be assembled must have the qualification certificate of the inspection department before assembly.

L The parts must be cleaned and cleaned before assembly, without burrs, flash, oxide skin, rust, chips, oil stains, colorants and dust.

L Before assembly, the main fit dimensions of parts and components, especially the interference fit dimensions and relevant accuracy shall be rechecked.

L Parts shall not be knocked, bumped, scratched or rusted during assembly.

L When fastening screws, bolts and nuts, it is forbidden to strike or use inappropriate screwdrivers and wrenches. The screw groove, nut, screw and bolt head shall not be damaged after fastening.

L For fasteners with specified tightening torque requirements, torque wrenches must be used and tightened according to the specified tightening torque.

L When the same part is fastened with multiple screws (bolts), all screws (bolts) shall be tightened crosswise, symmetrically, step by step and evenly.

L The taper pin shall be painted with the hole during assembly, and its contact rate shall not be less than 60% of the fitting length, and shall be evenly distributed.

L The flat key and the two sides of the keyway on the shaft shall be in uniform contact, and there shall be no gap between their mating surfaces.

L The number of tooth surfaces that the spline assembly contacts at the same time shall not be less than 2/3, and the contact rate shall not be less than 50% in the direction of the length and height of the key teeth.

After the flat key (or spline) with sliding fit is assembled, the corresponding accessories can move freely without uneven tightness.

L Excess adhesive shall be removed after bonding.

L The bearing outer ring, open bearing seat and semicircle hole of bearing cover shall not be stuck.

L The outer ring of the bearing shall be in good contact with the semicircular hole of the open bearing seat and bearing cover. During the color inspection, it shall be in uniform contact with the bearing seat at 120 ° symmetrical to the centerline and with the bearing cover at 90 ° symmetrical to the centerline. When checking with a feeler gauge within the above range, the 0.03mm feeler gauge shall not be inserted into 1/3 of the outer ring width.

L The bearing outer ring shall contact the end face of the locating end bearing cover evenly after assembly.

L The rolling bearing shall rotate flexibly and stably by hand after installation.

L The joint surface of the upper and lower bearing pads shall be close to each other and cannot be checked with a 0.05mm feeler gauge.

L When fixing bearing pads with locating pins, drill, ream and match pins under the condition that the pad mouth surface and end face are flush with the opening and closing surfaces and end faces of the relevant bearing holes. The pin shall not be loose after driving.

L The bearing body and bearing seat of spherical bearing shall be in uniform contact, and the contact shall not be less than 70% when checked by painting method.

L When the surface of the alloy bearing liner is yellow, it is not allowed to use. There is no nucleation within the specified contact angle. The nucleation area outside the contact angle shall not be greater than 10% of the total area of the non-contact area.

L The reference end face of the gear (worm gear) should fit with the shaft shoulder (or the end face of the positioning sleeve), and cannot be checked with a 0.05mm feeler gauge. The perpendicularity between the gear reference end face and the axis shall be ensured.

L The interface between the gearbox and the cover shall be in good contact.

L Before assembly, strictly check and remove the sharp corners, burrs and foreign matters left during part processing. Ensure that the seal is not scratched during installation.

6. Casting requirements:

L The casting surface shall be free of cold shut, crack, shrinkage cavity, penetrating defects and serious defects (such as under casting, mechanical damage, etc.).

L The casting shall be cleaned without burr and flash, and the gate and riser on the non machining indication shall be cleaned and flush with the casting surface.

L The casting words and marks on the non machined surface of the casting shall be clear and legible, and the position and font shall meet the drawing requirements.

L The roughness of the non machined surface of the casting, R for sand casting, is not greater than 50 μ m.

L The casting shall be cleaned of the sprue, riser, flying thorn, etc. The residual amount of gating and riser on the non machined surface shall be leveled and polished to meet the surface quality requirements.

L The molding sand, core sand and core bone on the casting shall be cleaned.

L For the inclined parts of the casting, the dimensional tolerance zone shall be symmetrically arranged along the inclined plane.

L The molding sand, core sand, core bone, fleshy, sticky sand, etc. on the casting shall be spaded and cleaned.

L Correction shall be made for the wrong type and boss casting deviation to achieve smooth transition and ensure the appearance quality.

L Wrinkles on the non machined surface of the casting shall be less than 2mm deep and more than 100mm apart.

L The non machined surfaces of machine product castings shall be shot blasted or roller treated to meet the requirements of cleanliness Sa2 1/2.

Castings must be water toughened.

L The casting surface shall be flat, and the gate, burr and sand shall be removed.

L The casting shall be free from cold shut, crack, hole and other casting defects detrimental to use.

7. Coating requirements:

L Rust, oxide skin, grease, dust, soil, salt and dirt must be removed from the surface of all steel products to be coated before painting.

L Before rust removal, use organic solvent, lye, emulsifier, steam, etc. to remove grease and dirt on the surface of steel products.

L The time interval between the surface to be painted after shot blasting or manual rust removal and the primer shall not be more than 6h.

L The surfaces of riveted parts in contact with each other must be coated with 30~40 μ m anti rust paint before connection. The overlapping edges shall be sealed with paint, putty or adhesive. The primer damaged due to processing or welding shall be repainted.

8. Piping requirements:

L Before assembly, all pipes shall be free of flash, burr and chamfer. Use compressed air or other methods to clear the sundries and floating rust attached to the inner wall of the pipe.

L Before assembly, all steel pipes (including prefabricated pipes) shall be subject to degreasing, pickling, neutralization, water washing and rust prevention.

L During assembly, screw down the pipe clamp, support, flange, joint and other parts fixed by threaded connection to prevent looseness.

L The welding parts of prefabricated pipes shall be subject to pressure test.

L When piping is replaced or transferred, the pipe separation port must be sealed with tape or plastic pipe to prevent any foreign matters from entering, and a label must be attached.

9. Requirements for repair welding parts:

L The defects must be completely removed before repair welding, and the groove surface shall be smooth and smooth without sharp corners.

L According to the defects of steel castings, the defects in the repair welding area can be removed by digging, grinding, carbon arc air gouging, gas cutting or machining.

L Sand, oil, water, rust and other dirt in the repair welding area and within 20mm around the groove must be thoroughly cleaned.

L During the whole process of repair welding, the temperature of the preheating area of the steel casting shall not be lower than 350 ° C.

L If conditions permit, welding shall be carried out in horizontal position as far as possible.

L During repair welding, the welding rod shall not swing laterally.

L When the surface of steel casting is welded, the overlap between weld beads shall not be less than 1/3 of the weld bead width.

10. Forging requirements:

L The nozzle and riser of each steel ingot shall have enough removal to ensure no shrinkage cavity and serious deflection of forgings.

L Forgings shall be forged and formed on a forging press with sufficient capacity to ensure full internal penetration of forgings.

L Forgings are not allowed to have visible cracks, folds and other appearance defects affecting use. Local defects can be removed, but the cleaning depth shall not exceed 75% of the machining allowance. Defects on the non machined surface of forgings shall be cleaned and smoothly transited.

Forgings are not allowed to have white spots, internal cracks and residual shrinkage cavities.

11. Cutting requirements:

L The parts shall be inspected and accepted according to the process, and can be transferred to the next process only after the previous process passes the inspection.

L The machined parts are not allowed to have burrs.

L The finished parts shall not be placed directly on the ground, and necessary support and protection measures shall be taken. The machined surface shall be free of rust and other defects that may affect the performance, service life or appearance.

L The surface for rolling finishing shall be free of peeling after rolling.

L There shall be no oxide scale on the surface of parts after heat treatment in the final process. The finished mating surface and tooth surface shall not be annealed, bluish or discolored.

The machined thread surface shall be free of defects such as black skin, bump, random thread and burr.