I. Process audit
The material requirement of this part is QT450. The longest dimension is115 mm. Quantity requirement 10 piece, belonging to single piece and small batch production.
Second, the processing technology card
Process number, process name, process content, process drawing, positioning surface, installation method, machine tools and equipment.
Casting, cleaning the bottom surface and forming the whole mold.
Ⅱ. Roughly milling (1) the bottom of the workpiece
(2) Roughly milling the bottom surfaces of two sides (1) and two sides (2)
Vice vertical milling machine
Iii. reaming (1) drill φ 30 holes with twist drill and reamer successively.
(2) Install a drilling machine on the chamfered bottom surface and the panel bending plate.
Ⅳ Drill both sides of φ 1 1, φ 8 and φ 10 holes respectively, and use the auxiliary drill to drill holes.
ⅴ Milling (1) Milling the countersink of φ 1 1 with a milling machine, and the hole depth is 10.
(2) Milling a countersink of φ 16 on the hole of φ 10 with a milling machine, wherein the depth of the hole is 10, and vertical milling machines are installed on both sides of the hole.
ⅵ Boring ⅵ 10-ⅵ 8 Tapered hole, boring both sides with boring cutter, and vice vertical milling machine.
ⅶ Saw the seam with 2mm at the bottom and the auxiliary saw blade.
ⅷ tapping both sides of the thread, tapping the tap.
ⅸ heat treatment: the casting is quenched and tempered at low temperature.
ⅹ Milling, Finishing, Bottom Milling and Two-sided Vertical Milling Machine
ⅶ finely hinge the bottom of φ30 hole, and install the drilling machine on the disc bending plate.
Inspection according to the requirements of drawings.
Three, mechanical processing technology design specification
(A) Process design analysis
Workpiece blank is a casting. Before machining after casting, it should be cleaned and annealed to eliminate the internal stress produced in the casting process.
According to the drawing information, the processing quantity is 10 pieces, the quality of parts is below 100kg, and the production type belongs to single piece production.
In the case of single-piece production, the main technological process of open support can be considered as follows:
(1) The original view is missing some dimensions, and it is completed after analysis; Some old national standards have been replaced by new ones; The material is nodular cast iron, which is a common material and easy to prepare and process.
(2) The parts do not interfere with the demoulding structure, so it is reasonable and economical to process all surfaces after casting.
(3) The holes that are not cast on the parts can be drilled directly by the drill-hinge-hinge process, and the accuracy requirement is not high.
(4)φ30 hole not only has certain accuracy, but also requires the parallelism of the bottom surface, so the bottom surface should be processed first, and then the hole should be processed according to its positioning.
(5) In order to ensure the relative position accuracy of each structure of the part and the shape accuracy of the hole, the machining task should be completed in the same loading on the same machine tool as far as possible.
(6) For screw holes and saws with low requirements, they can be put in the final processing. This can prevent this part of man-hours from being wasted due to problems in the processing of the main surface or hole.
(7) In order to ensure the accuracy and roughness of parts, the whole process is divided into two stages: rough machining and finish machining, and the same positioning datum should be adopted.
(8) When assembling, the two tapered pin holes should be matched, and no machining is needed when machining parts.
(2) Selection and comparison of surface processing methods of parts.
(1) The roughness requirements of the three main machining planes of the parts are high (Ra value is 3.2), and the economic accuracy of the milling machine can meet the requirements with high machining efficiency. If you choose planing, the efficiency is not high, and two of the surfaces are irregular, which is not conducive to cutting with a planer.
(2) The hole system on the bottom surface does not require high accuracy, so it is thirsty to drill with a drilling machine.
(3) The hole roughness of φ 30 is 1.6, and the position accuracy is required. According to the machined bottom surface, the drilling-reaming-reaming process is selected. If you choose the drilling-boring process, you can also meet the requirements, but the size of the hole is mainly ensured by operation, unlike drilling-hinge-hinge, which is ensured by the size of the tool itself, and largely depends on the level of workers, so it is not easy to process qualified products, so the drilling-hinge-hinge process is not as economical as it is.
(4) The inner surface roughness of φ16 counterbore is required to be 12.5, which can be met with high efficiency end milling cutter.
(5) The inner surface roughness of φ10-φ 8 taper hole is required to be 1.6, which requires fine boring. In order to reduce the number of clamping, boring is carried out directly on the vertical milling machine.
(6) directly saw out the groove on the right side of the part. Tap the thread M 10.
(3) Selection of benchmarks and installation methods
1. Benchmark selection
(1) One side of the coarse datum is selected as the coarse datum, because its size is large enough, the clamping is stable and the machining allowance is uniform.
(2) Selection of precision datum The bottom surface and the other side surface are selected as precision datum, which conforms to the principle of datum unification and datum coincidence and is conducive to ensuring machining accuracy.
2. Selection of installation method
(1) When milling, install it with a vise, which is a universal fixture and easy to install. * * * Installed twice, the first time to process the rough datum, and the second time to process the other two planes.
(2) When processing Φ 30 hole, choose the disc bending plate for installation, because the shape of the part is irregular, and the axis of the hole is required to be parallel to the installation surface. * * * Installed twice. All processes except one chamfer are processed for the first time, and the remaining chamfers are processed for the second time.
(3) When processing countersunk holes, press plate bolts are selected for installation, and the installation is stable, and the required surface can be processed after one installation.
(4) When sawing and tapping, it is installed in a vice for easy processing. It needs to be installed twice, once for machining narrow seams (to prevent damage to the machined surface, wood chips or copper sheets should be padded) and once for tapping.
(4) Determination and distribution of machining allowance
There should be allowance (mm) for the process steps in the processing stage.
Surface roughness (mm)
(hmm)
Roughing and milling side face 2 9 1.5 12.5
Rough milling the other side and bottom surface 1 88/23.5 12.5.
Step hole processing 0 φ 16, φ 1 12.5.
Sawing 0 2
Reaming φ30 hole 8, φ 22 hole 0.3, φ 29.7 hole 12.5.
Deformation allowance of heat treatment and annealing 1
Finishing and milling side A 0 86.5 3.2
Finish milling the other side and bottom surface 0 85 3.2
Thick hinge, thin hinge φ30 hole 0. 1, φ29.9 0, φ 30 hole 1.6.
(5) Rough economic analysis
According to the online inquiry, the price of QT450 is about 7000 yuan/ton, and the weight of each blank is about 4kg, so the blank price =7×3× 10=2 10 yuan.
The man-hour for processing an open bearing is about 1 hour, and the labor cost of the master is 30 yuan, so the labor cost of * * * is about 30× 10=300 yuan.
Total cost =2 10+300=5 10 yuan.