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Course No.: Student No.：
Course Project:
Manufacturing Technology Design
Title The machining process and fixture design of the support
Student Name Wang Ting
Class Mechanical Design Engineering and Automation (English)151
Student No. 201535510120
Department/College Engineering Institute
Advisor Dr. Wang
Date Nov.06 2018
II
Course Project: Manufacturing Technology Design
Design Instruction on
Course Project: Manufacturing Technology Design
Design Assignment
Title：Design of special fixture for upper end face of bearing block
Content：
1) Manufacturing process planning sheet 1
2) Assembly drawing of Fixture or jig 1
3) Detail drawing 1 / part
4) Design Instruction 1
5) Assembly animation 1
Course Project: Manufacturing Technology Design
Contents
Abstract 3
Chapter 1 Preface 4
Chapter 2 Process analysis of workpiece 4
2.1 Function of workpiece 4
2.2 Process analysis of parts 5
Chapter 3 Blank part determination 6
Chapter 4 Manufacturing process planning 7
4.1 Selection of positioning reference 7
4.2 Making process route 7
Chapter 5 Cutting parameters and labor-hour 10
5.1 Determination cutting parameters and Time quota calculation 10
Chapter 6 Jig/Fixture design 13
6.1 Design duty 13
6.2 Locating datum 13
6.3 Fixture Degree of freedom analysis 14
Chapter 7 Fixture design and usage of equipment 15
7.1 Fixture design 15
7.1.1 locating and clamping of the workpiece 15
7.1.2 Analysis of location errors 16
7.2 Calculation of cutting force and clamping force 17
7.2.1 Calculation of cutting force 17
7.2.2 Calculation of clamping force 18
7.3 Brief description of fixture design and operation 19
Chapter 8 Conclusion 21
References 22
Thanks 22
Abstract
The design course is a teaching link on the basis of finishing the course Technology of Mechanical Manufacture (including machine tool fixture design)and most of the specialized courses. It is a design of special fixture mainly for the processing technic of parts and some procedure processing of parts. From the process of the parts, it mainly analyses what problems should pay attention in the processing, and what methods and process should be adopted to ensure the accuracy and raise labor productivity. As far as special clamp is concerned, good fixture design can improve product productivity, accuracy, reduce costs and so on, and can also expand the scope of use of machine tools, so that improve the production efficiency and reduce the costs under the premise of ensuring accuracy. This design enables us to apply the basic theory of manufacturing technology, combining with practical knowledge gained from production practice, and analyze and solve process problems independently. Besides, it enables us to master the ability to design a process specification for a moderately complex part (shell) and the knowledge of the basic principles and methods of fixture design. This design is also a practice shot of drawing up jig design plan, completing jig structure design ability, being familiar with and using relevant manuals, charts and other technical data and writing technical documents and other basic skills, which lays a good foundation for future graduate design and future work.
Due to limited capacity, lack of experience, there are many inadequacies in the design, I hope the teacher will be more advice.
Key words: process planning, design, special fixture
Chapter 1 Preface
In recent years, with the rapid development of machinery manufacturing industry, manufacturing technology in processing is also developing continuously, and the application of various machine tools is becoming more and more extensive, and various parts are also increasingly demanding. This design carries on the technological analysis to its fork parts, and formulates the reasonable processing procedure for this part is an effective measure to guarantee the processing quality of the parts.
According to this topic, the basic design contents include:
1. According to the "bearing seat" part drawing, process analysis is carried out, and the technical requirements of each surface of the part are analyzed.
2. According to element formulate the mechanical process.
3. Draw up the fixture assembly drawing of the special process.
4. Write design instructions.
Chapter 2 Process analysis of workpiece
2.1 Function of workpiece
This time, the part is the bearing seat. The bearing seat is usually installed on a machine tool. The corresponding connecting hole of the bearing seat relates to the corresponding connecting screw or the connecting shaft. The central hole and the corresponding bearing on the shaft cooperate with each other. With the rotation of the shaft, it is necessary to ensure that the central hole and the shaft have a certain concentric effect.
2.2 Process analysis of parts
Some surfaces to be machined in this bearing seat parts mainly include the wide grooves on the upper end face and the upper end face, the wide grooves on the right lower end face and the right lower end face, the opposite lower end face of the upper wide groove, the opposite end face of the right wide groove, and the front and rear end face of the φ250. The surface features of the front and back face of the φ250 are thick. The roughness requirement is Ra6.3, and the wide groove 50h11 requirement of the two parts is Ra6.3. In addition, the other specified surface roughness requirements are Ra12.5, and the unspecified surface roughness requirements are all non-processed.
The characteristics of the hole include the large circular hole φ180H7 on the center datum. The surface roughness requirement of the hole is Ra1.6, the surface roughness requirement of the 2-φ25 hole on the upper wide groove and the right lower wide groove is Ra12.5, and the through hole requirement of the 6-φ13 hole on the large end face is Ra12.5.
In the form tolerance requirements, the verticality between the upper end face and the lower right end face is 0.12 mm, center large circle hole φ180 degrees roundness requirement 0.008mm, Large end faceφ250 is the base B. Center large circular hole φ180 is the base C. Two wide grooves have positional 0.4mm requirements relative to the B datum. The front and rear faces have the requirement of perpendicularity 0.1mm relative to the C datum center.
Chapter 3 Blank part determination
Choosing the right blank has a very important impact on the subsequent processing. It also has a significant impact on the material and manufacturing method of the blank, as well as the manufacturing accuracy of the blank on the subsequent processing quality of the workpiece.
Therefore, it is very important to determine the manufacturing form of the blank. The bearing seat is considered to be mass production. According to the shape of the parts, the blank is HT200. The material of this time is grey cast iron. Castings are needed for the blank.
Chapter 4 Manufacturing process planning
4.1 Selection of positioning reference
When parts are processed, it is generally called rough datum when the surface which is not processed on the blank is chosen as the positioning datum, and precise datum when the processed surface is used as the positioning datum after subsequent processing. Generally speaking, rough datum selection chooses large, long, regular surface features, appropriate location and other ways to select.
Generally, we must consider the rough datum of starting processing. Basically, the rough datum can choose the shape characteristics of the non-processing. Obviously, the bearing seat parts can be chosen as the rough datum when choosing the large end face. Fine benchmark selection needs to select the basic benchmark characteristics after processing. The center hole 180 can be used as fine benchmark after processing.
4.2 Making process route
Aiming at the bearing seat parts, this paper determines two process routes, and compares and chooses the best one. as follows:
Process one: casting blank
Process two: rough and fine milling 250 front end face.
Process three: rough and fine milling 250 100mm, ensure the size of the end face.
Process four: coarse and fine boring center hole 180H7 in place.
Process five: milling the upper end and the right side.
Process six: milling upper and lower ends and lower right sides to ensure two parts size 50mm
Process seven: milling the upper end and wide groove on the right side face to ensure the size 50mm
Process eight: drill and expand 2- 25 holes.
Process nine: drill 6- 13 holes.
Process ten: deburring chamfering
Process Eleven: Inspection and warehousing
Preliminary processing procedures are as follows:
Operation number
Contents of working procedures
Equipment
Tools
10
Casting blank
Sand mould
Sand mould manufacturing equipment
20
Milling the bottom surface
milling machine
Facing cutter
30
Milling the upper surface
milling machine
Facing cutter
40
Milling two side surfaces
milling machine
Milling tool,
Carbide chip
50
Milling groove side
milling machine
Milling tool,
Carbide chip
60
Drilling holes of the sides surface
Porous group drilling machine
Drilling bit
M24(through the wall of shell and distribute even)
70
1.Boring bearing holes roughly(φ180mm)
Boring lathe
Rough boring tool
2.Chamfering
Rose reamer
80
Finishing boring bearing holes
Boring lathe
Composite boring tool
90
Milling inner small end face
Milling machine
Milling tool Carbide chip
100
Drilling holes of the infront surface
Numerical control milling machine
Drilling bit
M12(through the wall of shell and distribute even)
110
Curettage cavity
Upright drill
hobbing
120
Wash
Cleaning
machine
130
Test
Checkout console
Technics card of machining process can be seen on the appendix.
Chapter 5 Cutting parameters and labor-hour
5.1 Determination cutting parameters and Time quota calculation
Operation 40 Milling two side surfaces
Machined part material: HT200
Machine tool selection: vertical milling machine X53K
Selection of tools: sleeve end mill, diameter 50mm, tooth number Z=8.
Milling depth: ：
Feed per tooth ：According to table 1, get
Table 1
Milling speed ：According to table 2，get
Table 2
Spindle speed of machine tool: ：，
Feed rate ：
Worktable feed per minute ：
According to the basic time calculation of milling in Table 5-47 of the Course Design Guidance Course of Machinery Manufacturing Technology, this is a sleeve face milling cutter. The basic time calculation formula of milling is as follows.
In this formula,
Milling length of workpiece:
Tool cut in length：
In this formula,
the nominal width of milling is shown in table 5-11. The width of the face milling cutter diameter 50mm is 24mm.
：milling cutter diameter 50mm
Bring these two values into the formula. Can get
，and
Cutting length of cutting tool：get ，this time we choose 3mm.
Horizontal feed of worktable ：
Number of knives
Maneuver time
Chapter 6 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.
6.1 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.
6.2 Locating datum
The design of the special fixture for the upper end face of the bearing seat is carried out in this paper. The positioning principle method adopted is based on the six-point positioning principle. The basic schematic diagram of the six-point positioning principle is as follows.
6.3 Fixture Degree of freedom analysis
In this paper, the main positioning datum of 250 is used to limit three degrees of freedom. Four supporting nails are used as positioning elements. Three supporting nails are used as positioning elements to limit three degrees of freedom. The other one plays a strengthening role and does not consider the limitation of freedom.
The right end face restricts its two degrees of freedom. The supporting pin is used as the positioning element, and the lower part of the end face also uses the supporting pin positioning element to restrict one degree of freedom. So the positioning principle of the whole device is basically the same as the original method diagram according to the six-point positioning principle.
Chapter 7 Fixture design and usage of equipment
7.1 Fixture design
The fixture is as followed.
7.1.1 locating and clamping of the workpiece
In this paper, the main positioning datum of 250 is used to limit three degrees of freedom. Four supporting nails are used as positioning elements. Three supporting nails are used as positioning elements to limit three degrees of freedom. The other one plays a strengthening role and does not consider the limitation of freedom.
The right end face restricts its two degrees of freedom. The supporting pin is used as the positioning element, and the lower part of the end face also uses the supporting pin positioning element to restrict one degree of freedom. So the positioning principle of the whole device is basically the same as the original method diagram according to the six-point positioning principle.
7.1.2 Analysis of location errors
One of the positioning methods of this time is that the right end and the lower end are two perpendicular planes. The positioning errors can be analyzed as follows.
Through two vertical plane positioning tolerance analysis, the following formula is calculated.
The is selected at 90 degrees. The two sizesandof the side of the positioning are 30 and 35, respectively. After substituting this formula, we can get the result
The positioning error accounts for sixteen percent of the machining tolerance, which ensures the machining requirements.
The positioning scheme can meet the accuracy requirements of the machining, and the positioning scheme is reasonable.
7.2 Calculation of cutting force and clamping force
7.2.1 Calculation of cutting force
The milling end is adopted, and the milling force is calculated according to the following formula. The milling cutter is cylindrical milling cutter, vertical milling cutter, disc milling cutter, saw blade milling cutter, angle milling cutter, semicircle shaped milling cutter.
In this formula,
：cutting force
：When using high speed steel milling cutter, select the coefficient of workpiece material and milling cutter type.
：Milling depth
：Feed per tooth
：Milling cutter diameter
：Milling width
：Milling cutter speed per minute
：Tooth number of milling cutter
：When the high-speed steel is milling, the modification coefficient of the mechanical properties of the workpiece material is different. For structural steel, cast steel is ，
：Tensile strength of workpiece materials MPa
=2451N
7.2.2 Calculation of clamping force
Because the clamping of the workpiece is clamped above the bottom of the workpiece. According to the third edition of the "Machine Tool Fixture Design Manual", when the other cutting forces in the middle are small, only a small clamping force is needed to prevent the vibration and rotation of the workpiece in the process of processing.
In this formula,
：Prime motivity
：Actual clamping force required
：Equivalent friction radius between end screw and workpiece
：Half of thread diameter
：Thread lift angle
：Friction angle between screw end and workpiece
：Equivalent friction angle of helix pair
：Mechanical efficiency
The calculation is as follows：
Wk =2451N
r' = 3
φ1 = 3.2
rz = 6.9
α = 2.5
φ'2 = 9.83
L = 43
η0 = 0.88
l = 21
Calculation results = 2945N
7.3 Brief description of fixture design and operation
The fixture of this time is the fixture for milling the upper face. Although the feature surface of the workpiece is two different positions, the feature of the milling face is exactly the same after the workpiece is rotated. Two different locations can be machined by means of a fixture. After milling a feature, it needs to be disassembled and pressed down. The nut on the large end face of the workpiece, and then the movable supporting block on the right side is removed, the workpiece can be taken down, and then the workpiece can be turned over, so that another feature can be operated on the same fixture, thus saving the installation time of the workpiece and facilitating the operation.
The assembly drawings of the whole fixture are as follows
Chapter 8 Conclusion
Bearing seat is a basic part, its performance directly affects the overall processing effect of the connecting shaft and bearing parts, and then affects the precision relationship of the processing parts. Therefore, the research topic of the rear bearing seat parts process analysis is very good in combination with the knowledge learned in textbooks, and the application of mechanical processing manufacturing technology, process analysis of this part and the final fixture design.
Several conclusions are drawn from the design of the technological process of the bearing block and the fixture design of the main process.
1. Firstly, the technological characteristics of the parts are analyzed, and the technological rules of the parts are formulated, the technological process of the parts is formulated, and the design method of the technological rules of such parts is familiar with.
2. After making the process of the parts, the main process is analyzed, and one of the main processes is chosen as the task of fixture design. This choice is the milling end fixture design.
3. Milling the upper end fixture makes me familiar with the six-point positioning principle of such parts, the selection of positioning elements using supporting nails, and the screw pressing method of the end plate on the surface.
References
[1]李益民主編 《機械制造工藝簡明手冊》 機械工業(yè)出版社，2003；
[2]周開勤主編 《機械零件手冊》 高等教育出版社，2006
[3]吳宗澤主編 《機械零件設計手冊》 機械工業(yè)出版社，2003
[4]陳宏均主編 《實用機械加工工藝手冊》 機械工業(yè)出版社，2005
[5]毛倩德主編 《袖珍機械設計師手冊》機械工業(yè)出版社，2005
[6] 《機床夾具設計手冊》第二版，上海科學技術出版社，1994,12
Thanks
Through this fixture design course, I learned the whole process of bearing seat processing, SolidWorks drawing skills, understand the necessary process and requirements of mechanical processing. Thank you, Mr. Wang Linlin, for teaching.