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Course No.: Student No.：
Course Project :
Manufacturing Technology Design
Title Machining process specification and technological equipment of shell parts
Student Name 屠奇瑤
Class Mechanical Design 、Engineering and Automation (English)151
Student No. 201535510108
Department/College Engineering Institute、Vocational and technical education Institute
Advisor Dr. Wang
Date 2018.11.09
II
Course Project: Manufacturing Technology Design
Design Instruction on
Course Project:
Manufacturing Technology Design
Design Assignment
Title：Machining Process Specification of Shell Parts and Special Clamp for Milling Two Side Faces Process
Content：
1) Manufacturing process planning sheet 1
2) Assembly drawing of Fixture or jig 1
3) Detail drawing 1 / part
4) Design Instruction 1
Student Name Tu Qiyao
Class Mechanical Design 、Engineering and Automation (English)151
Student No. 201535510108
Department/College Engineering Institute、Vocational and technical education Institute
Advisor Professor Wang
Date 2018.11.09
Course Project: Manufacturing Technology Design
Content
Content 3
Abstract 3
Chapter 1 process analysis of parts 5
1.1 Part action and structure 5
1.1.1 function of parts 5
1.1.2 structural features of parts 6
1.2 key surface technical requirements for parts 6
Chapter 2 process planning design 7
2.1 selection of blank and size determination 7
2.2 preparation of process routes 8
2.2.1 selection of crude and fine benchmark 8
2.2.2 surface processing methods 8
2.3 preparation of machining program 9
Chapter 3 Manufacturing process planning 10
Chapter 4 Jig/Fixture design 11
4.1 Design duty 12
4.2 Locating datum 12
4.3 Fixture program 12
Chapter 5 Clamping force calculation 13
5.1 Fixture design 13
5.1.1 locating and clamping of the workpiece 14
5.1.2Milling slot 10 mm wide 15
5.1.3 Calculation of clamping force 16
Chapter 6 error analysis 18
Chapter7 Fixture design and usage of equipment 19
7.1design of knife device 19
7.2instruction of clamping operation 19
Chapter 8 Conclusion 21
References 22
Thanks 24
Abstract
Machining manufacturing is a basic discipline of mechanical specialty, which is widely used in practice.
This design is aimed atthe design of the manufacturing process flow of the bearing seat of the part, and the special fixture design for this part. This paper introduces the whole processing process of this part product in detail. Through analyzing the technical requirements of the part, the degree of processing required for each machining surface is determined, the processing process scheme is reasonably determined, and the process card and process card of machining process are formulated. The special fixture is designed for two main processes.
According to the existing condition, in the process of technological design in the traditional mechanical processing, process planning formulation needs according to the characteristics and the structure of the parts are processed performance requirements, and then according to the reality of the conventional processing route to carry on the processing and manufacturing, so that better product quality and technical performance to ensure that the parts, but also embodies the parts processing characteristics of the product.
In addition, in the design of special jig, special jig that conforms to the actual processing conditions is adopted for the main processes, which saves the processing time and improves the labor efficiency. Although the cost of processing is slightly increased, it is more conducive to the replacement and maintenance of the jig later and increases the utilization rate of materials.
Keywords: bearing housing; Fixture design; Process planning design
Chapter 1 process analysis of parts
1.1 Part action and structure
1.1.1 function of parts
This part is the bearing seat. The bearing seat is usually installed on a machine tool. The corresponding connecting hole of the bearing seat is connected with the corresponding connecting screw rod or connecting shaft.
1.1.2 structural features of parts
From the perspective of shape, this part is relatively standard. The main part structure includes the main processing features of the large hole in the center, and the processing features to be carried out by two side planes.
1.2 key surface technical requirements for parts
To processing some of the surface of the bearing parts, mainly including its face and wide groove on the surface of the upper and the lower right side of the face and on the lower right side end face of wide groove, on his men along the surface and the lower left along the surface, phi before and after the end of 250, the surface characteristics of phi 250 before and after the end of the surface roughness request for Ra6.3, two parts of 50 h11 require wide groove is also Ra6.3, in addition to the rest of the state that the surface roughness of the requirements are Ra12.5 did not indicate the surface roughness were not processed.
The characteristics of the hole include that the large circular hole on the central datum is generally 180H7, the surface roughness of the hole is required to be Ra1.6, the surface roughness of the upper and lower right holes is required to be Ra12.5, and the surface roughness of the upper and lower right holes is required to be Ra12.5.
The vertical degree between the middle and upper end face and the right lower end face is required to be 0.12mm, while the center large circular hole is required to be 0.008mm.
Chapter 2 process planning design
2.1 selection of blank and size determination
The correct selection of blank has a very important influence on the subsequent processing. For the raw materials and manufacturing methods of the blank, the manufacturing precision of the blank also has a significant influence on the subsequent processing quality of the workpiece.
Therefore, it is very important to determine the manufacturing form of the blank. This time, the bearing seat is considered to be mass production, and the blank is determined to be HT200 according to the shape of the parts. This time, the material is gray cast iron
According to the mechanical manufacturing technology foundation course design guidance tutorial on casting blank, choose the parts of the surface of the basic characteristics of the casting blank and machining of the net size relative to consider machining allowance, query the book table 2 to 25, draw a plane machining allowance, the thickness of surface is greater than 50 mm, width is between 200 and 400 mm, so rough machining allowance of 2.5 mm, half finishing allowance of 1.5 mm, on end face and lower end face similarly also according to the rough machining allowance of 2.5 mm. When the center hole is roughmachined to 3mm, the semi-finishing to 2mm and the finishing to 1.0mm, it is concluded that the size of the blank of the center hole which is join180-3-2-2-1 is equal to join168.
The thickness of the blank is 100+2.5+1.5+2.5+1.5=108mm.
2.2 preparation of process routes
2.2.1 selection of crude and fine benchmark
When the parts are processed, the rough benchmark for starting the processing should be considered generally. Basically, the rough benchmark can choose the shape feature that is not processed. Obviously, the large front and rear end face can be selected as the choice of the rough benchmark. The selection of fine datum needs to select the basic datum features after processing. In this case, center big hole and front and rear large end face can be selected as the selection of fine datum.
2.2.2 surface processing methods
In terms of the basic features of the bearing pedestal parts this time, it is mainly the processing of the basic features of the surface and bore. Basically, the milling process can be selected based on the processing method of the surface. Rough milling is adopted for the roughness machining surface of R a12.5; rough milling and semi-fine milling are used for Ra6.3; rough milling and fine milling are used for Ra3.2 and Ra1.6. The hole is 180 adopted rough, semi-fine boring, fine boring all can achieve the requirements.
2.3 preparation of machining program
The starting point of the process route. The technical requirements such as geometrical shape, dimension accuracy and position accuracy of the parts should be reasonably guaranteed. In the production program, the conditions for mass production should be determined, and special jigs should be used in general machine tools, and as much as possible, to improve productivity. The processing route of the current bearing housing is as follows:
Operation number
Name
operation
10
Casting
Casting the
blank type
20
Milling
Milling the bottom surface
30
Milling
Milling the upper surface
40
Milling
Milling two side surfaces
50
Milling
Miling groove side
60
Drilling
Drilling holes of the sides surface
70
Boring
Boring bearing holes roughly(φ180mm)
Chamfering
Chamfering
80
Boring
Finishing boring bearing holes
90
Milling
Milling inner small end face
100
Drilling
Drilling holes of the infront surface
110
Curettage cavity
120
Washing
130
testing
Chapter 3 Manufacturing process planning
The first step in the process is to select the location reference.For the positioning reference selected can ensure the whole machining process smoothly,usually how to process the surfaces should be first considered,and then consider how to choose the rough datum as the surface of the precise datum to process first.
1．Selection of precise datum
The bottom surface and holes 6-φ11 are not only the assembly standard,but also the design datum.Using them to do precise datum can make the processing follow the principle of "datum coincidence",and realize the typical positioning method of "one side,one hole"of the box parts.The processing of the remaining surfaces and holes can also be positioned with it,so that the process route respects the principle of "benchmark unification".In addition, the bottom surface area is relatively large,so that the location is relatively stable,and the clamping scheme is relatively simple, reliable and easy to operate.
2．Selection of rough datum
According to:
① On the premise that all processing surfaces are guaranteed to be machined, the machining allowance of the important holes shall be as uniform as possible;
② A rotating part (such as a gear, shaft sleeve, etc) that fits into a casing and has sufficient clearance from the inside of the case;
③ Assure exact location and Reliable clamping.
In this case, the two wide slots of the bearing seat, namely the upper wide slot of the workpiece and the right wide slot, have the same characteristics. In the process of clamping their wide slots, consider using a universal method, so that this fixture can be used to process the wide slots of the two parts.
The choice of positioning scheme is: to the center circle hole phi 180 for a basic positioning base, the center circle hole can limit the workpiece four degrees of freedom, in addition to large end face can restrict the artifacts of a degree of freedom, in addition to prevent the workpiece, the choice to phi 25 hole for a benchmark limit freedom of its side, it is restricting the whole workpiece is completely at six.
Chapter 4 Jig/Fixture design
In order to improve labor productivity, guarantee the quality of processing and reduce the intensity of labor, special jigs should be designed when machining the parts.
The design of the fixture adopts a hinged connection, so it is time-consuming and laborious to clamp and release the workpiece. But because of its small size, the workpiece is easy to cut. Through the careful analysis and comparison of the scheme, the hinge type is adopted. This kind of clamping mechanism is simple in structure, reliable in clamping and large in versatility. It is widely used in machine tools and Fixtures.
4.1 Design duty
The location mode of milling two side surfaces is easy, but it still needs to limit six degrees of freedom. In order to ensure technical requirements, the key is to find the positioning datum. At the same time, we should consider how to increase labor productivity and reduce the intensity of labor.
4.2 Locating datum
According to the part drawing, the two side surfaces are perpendicular to the bottom surface, and before processing the side surfaces, the bottom surface has already been finished processed. So we choose the bottom surface as the positioning base datum(design dutam) to satisfied the requirements of vertical tolerance.
4.3 Fixture program
The starting point of designing the special fixture should be to ensure the geometry, dimension precision and position precision of the parts. In the production program has been identified as a large number of production conditions, the special fixture design should make the process convenient in clamping, and have high production efficiency.
Chapter 5 Clamping force calculation
5.1 Fixture design
The fixture is as followed.
5.1.1 locating and clamping of the workpiece
The workpiece is clamped on the clamp. Six degrees of freedom are limited by two bearing plates and two supporting seats, namely "one side and two supporting seats".
The screw and knob nut are used to clamp the workpiece. The clip has a u-washer and knobs for easy removal and adjustment.
5.1.2Milling slot 10 mm wide
Machine tool: milling machine X53K
Cutter: high - speed steel keyway milling cutter number of teeth Z=6
Amount of feed f: according to the "machinery manufacturing technology basic course design guide" table 5-15, take
Cutting speed V: refer to table 5-15 of mechanical manufacturing technology basic course design guide
Machine spindle speed:
Milling keyway to calculate, milling basic time formula as follows
Type in the
The cutting length of the workpiece
Cutting length: calculated according to 25mm,
The cutting length of the cutter: take, and choose 2mm this time
: table level feed
Mobile time
5.1.3 Calculation of clamping force
The clamping of the part is directly clamping the end face of the part.
According to the formula
In the type
: actual clamping force N required
F: the cutting force
(1) calculation of cutting force
The cutting force is milling force, then the cutting force is milling force
Formula is as follows
Type in the
F: cutting force N
: consider the type coefficient of workpiece material milling cutter when milling HSS milling cutter, and check the table
: milling depth mm
D: diameter of milling cutter is mm
: mm feed per tooth
B: milling width mm
Z: the number of teeth of the milling cutter
: the correction coefficients of different mechanical properties of workpiece materials are taken into account when milling HSS
The cutter diameter according to end face milling cutter phi 50 mm, cutter feed per tooth choice for = 0.1 mm, the width of the milling length is the length of 170, so B = 170 mm, the number of teeth on the cutter phi 50 of 8, then Z = 8, milling depth = 1.5 mm, according to the specifications of rough milling of milling cutter and milling bearing material is carbon steel material, the index of = 294, = 1
Plug in type
= 1595 n
So the cutting foce F=1595
Since K the safety factor is 1.5
So the clamping force is
Chapter 6 error analysis
In the special fixture for milling groove this time, the main positioning datum is the central large circular hole with the large end surface. Please analyze the error analysis of this main positioning.
When any side contacts (the pin is placed vertically)
In the type
: the minimum clearance between the locating hole and the locating pin
In this case, a hole and a plane are positioned in the form of any side contact and the positioning error formula of any side contact is adopted
In this case, the tolerance of the part hole of x 180H7 was z 180, so =0.04
The locating axis of the smu160 tolerance is 100. so =-0.04
Chapter7 Fixture design and usage of equipment
7.1design of knife device
The tool alignment device is composed of the tool alignment block and feeler gauge, which is used to determine the relative position of the cutter and fixture.
Since this procedure is to finish rough milling and fine milling of the broad groove of the bearing seat, and because the wide groove is to be machined on the surface with depth, right-angle tool blocks are selected.
The clamping block installed on the jig can make the jig work well before the processing of a batch of parts.
Select the machined surface to be higher than the height of the blade piece (1-2mm).
7.2instruction of clamping operation
The clamping method of milling groove clamp is to use end face for clamping, and the action of using circular nuts on both sides of end face for clamping is used. The slot milling jig is applicable to the wide slot milling fixture on the two parts, in the first such as wide groove is part of the wide groove processing is completed, at this time will be the upper round nut loosen the lock, pull out the right positioning of the limit pin, remove artifacts and flip, at this time will be lower right part of the wide groove to the horizontal upward direction, and then on the left there is a limit pin of the device, same aim the limit pin also on phi 25 on the part of the wide slot hole, will limit pin inserted into the hole, then round nut locking, this time can be processed to a wide on the right side of the slot, so the material both wide groove can be done in a special jig jacket, The purpose of fixture design is achieved.
The following is the assembly drawing of the entire clamping fixture with the bearing seat milling wide groove.
Assembly drawing of a wide groove fixture with a bearing seat
Chapter 8 Conclusion
The fixture design process is a relatively comprehensive summary of systematic knowledge. After the whole process, I think the power platform of knowledge is great, and a lot of knowledge points that were not noticed in the textbooks before are reflected in this design process. At first not much for design concept, basically all don't know how to begin, slowly for a period of time after the early stage of the knowledge of the query and the analysis of the case, especially used to go to the school library to found a lot of data, especially on those parts of the case, books have all kinds of fixture case in this regard, after detailed understanding and analysis, are basically has a degree of certainty, familiar with the various steps and design process of the structure, and also the field to a lot of physical structure of the clamp design base to understand it, a detailed know all kinds of fixture parts installation location, And during the processing, the specific action process of these parts, after learning from the on-site masters, gradually had a certain concept. These are a more detailed preparation work of my