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Course Project :
Manufacturing Technology Design
Title:The machining process and fixture design of the support
Student Name: 李澤楠
Class:Mechanical Design、Manufacturing and Automation (English)151
Student No: 201535510115
Department/College: Engineering Institute
Advisor: Dr. Wang
Date: 2018年10月31日
10
Course Project: Manufacturing Technology Design
Design Instruction on
Course Project:
Manufacturing Technology Design
Course Project: Manufacturing Technology Design
Design Assignment
Title:The machining process and fixture design of the support
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
Title:The machining process and fixture design of the support
Student Name: 李澤楠
Class:Mechanical Design、Manufacturing and Automation (English)151
Student No: 201535510115
Department/College: Engineering Institute
Advisor: Dr. Wang
Date: 2018年10月31日
Contents
Chapter 1 Process analysis of parts 4
1.1 Part action and structure 4
1.1.1 The role of the part 4
1.1.2 Part structure characteristics 4
1.2 Key surface technical requirements for parts 4
Chapter 2 Process design 6
2.1 Blank selection and blank size determination 6
2.2 Drafting of the route 7
2.2.1 Rough and precise benchmark selection 7
2.2.2 Surface processing method 7
2.3 Preparation of processing plan 7
Chapter 3 Process design 9
(1) rough milling 9
(2) Semi-finishing 10
(1) rough milling 12
Chapter 4 Drill six small hole fixture design 13
(1) Cutting force calculation 14
(2) Calculation of clamping force 15
Conclusion 18
References 19
Thanks 21
Preface
In recent years, with the rapid development of the machinery manufacturing industry, the manufacturing technology in processing is also constantly developing, the application of various machine tools is becoming wider and wider, and various parts are becoming more and more demanding. This design is for the process analysis of the bearing housing parts. It is an effective measure to ensure the processing quality of the parts by formulating reasonable processing procedures for the parts.
According to this issue, the basic design contents listed include:
1. According to the “bearing seat” part drawing, carry out process analysis and complete the blank drawing;
2. Develop a mechanical process flow synthesis card based on the mechanical process of the part;
3. Draw a fixture assembly drawing of the special process;
4. Write a design specification.
Key words: bearing housing; fixture design; process design
Chapter 1 Process analysis of parts
1.1 Part action and structure
1.1.1 The role of the part
The part is a bearing seat, and the bearing seat is generally mounted on a certain machine tool. The corresponding connecting hole of the bearing seat is connected with the corresponding connecting screw or the connecting rotating shaft, and the center hole and the corresponding shaft bearing cooperate with each other. As the shaft rotates, it is necessary to ensure that the center hole has a certain concentric effect with the shaft.
1.1.2 Part structure characteristics
The parts are still relatively standardized in terms of shape. The main part structure includes the basic features of the main hole as the main processing, and then assists the machining features to be performed on the two side planes.
1.2 Key surface technical requirements for parts
Some of the surfaces to be machined in this housing part mainly include wide grooves on the upper end surface and the upper end surface, wide grooves on the lower right side end surface and the lower right side end surface, upper lower edge surface and lower right left edge surface. , front and rear end faces of φ250, etc., the surface roughness of the front and rear end faces of φ250 is Ra6.3, and the width of 50h11 of the two parts is also Ra6.3, except for the other specified surface roughness requirements. For Ra12.5, no surface roughness is indicated.
The characteristics of the hole include a large circular hole φ180H7 on the center reference, the surface roughness of the hole is required to be Ra1.6, the surface roughness of the upper and lower right 2-φ25 holes is required to be Ra12.5, and the 6-φ13 through hole on the large end face The requirement is also Ra12.5.
The geometrical tolerance requires 0.12mm between the upper middle end and the lower right end. The center large round hole φ180 requires a roundness of 0.008mm, the large end surface φ250 is the reference B, and the center large round hole φ180 is the reference C. The two wide slots are relative to The B-reference has a positionality of 0.4 mm, and the front and rear large end faces have a verticality of 0.1 mm with respect to the C-reference center.
Chapter 2 Process design
2.1 Blank selection and blank size determination
The correct selection of the blank has a very important influence on the subsequent processing. For the material and manufacturing method of the blank, the manufacturing precision of the blank also has a significant impact on the subsequent processing quality of the workpiece.
Therefore, it is very important to determine the manufacturing form of the blank. The bearing housing is considered to be mass production. The blank is determined to be HT200 according to the shape of the part. The material of this time is gray cast iron. The casting is required to carry out the blank.
According to the blank determination of casting parts in the "Guidelines for the Design of Mechanical Manufacturing Technology Basic Courses", the casting blanks of the basic surface processing characteristics of this part and the net size of the processing should be considered in consideration of the machining allowance. Table 2-25, the machining allowance of the plane is obtained. The basic thickness of the plane is more than 50mm, the width is between 200 and 400mm, so the roughing allowance is 2.5mm, and the semi-finishing allowance is 1.5mm, the upper end surface and the lower right end surface are also treated according to the roughing allowance of 2.5mm. The center hole φ180 is 3 mm in roughing, 2 mm in semi-finishing, and 1.0 mm in finishing, so that the blank size of the center hole φ180 is φ180-3-3-2-2-1-1=φ168.
The thickness of the blank is 100+2.5+1.5+2.5+1.5=108mm.
2.2 Drafting of the route
2.2.1 Rough and precise benchmark selection
When machining parts, it is generally necessary to consider the rough reference to start machining. Basically, the rough reference can select the shape characteristics without machining. This time, the bearing housing parts obviously choose the front and rear large end faces as the rough reference. The fine reference selection needs to select the basic reference characteristics after processing. This time, you can select the center large hole and the front and rear large end faces as the selection of the fine reference.
2.2.2 Surface processing method
The basic characteristics of the bearing housing parts are mainly the processing of the basic features of the surface and the hole. Basically, the machining method of the surface is selected by milling, and the surface processed according to the roughness of R a12.5 is rough milling. Machining, Ra6.3 is rough milling and semi-finishing milling, and Ra3.2 and Ra1.6 are rough milling and finishing milling. The hole φ180 can be used in coarse, semi-precision and fine boring.
2.3 Preparation of processing plan
Develop a starting point for the process route. It should be reasonable to ensure the technical requirements of the geometry, dimensional accuracy and positional accuracy of the parts. In the production program to determine the conditions for mass production, it can be considered to use special fixtures on general-purpose machine tools, and try to improve the process as much as possible. productivity. The processing route of the bearing housing is as follows:
工序號 工序內(nèi)容
工序 1 鑄造毛坯
工序 2 粗、半精銑φ250后端面
工序 3 粗、半精銑φ250前端面尺寸100mm
工序4 粗、精鏜中心大孔φ180H7
工序5 銑上端面
工序 6 銑右下端面
工序 7 銑上部下端面
工序8 銑右側(cè)左端面
工序9 銑兩個寬槽50mm
工序 10 鉆擴2-φ25孔
工序11 鉆6-φ13孔
工序 12 去毛刺倒棱角
工序 13 檢驗入庫
Course Project: Manufacturing Technology Design
Chapter 3 Process design
3.1 Determination of process equipment
The process equipment of this bearing housing part includes the selection of processing equipment, the selection of tools and measuring tools as shown in the following table.
加工部位
加工工
藝方法
刀具
量具
設備及型號
名稱
規(guī)格
前后端面
粗銑 半精銑
鑲齒套式端面銑刀
φ80
游標卡尺
立式銑床X5032
上、右側(cè)端面
粗銑
套式端面銑刀
φ50
游標卡尺
立式銑床X5032
上部和右側(cè)下端面
粗銑
圓柱形銑刀
φ50
游標卡尺、游標深度尺
立式銑床X5032
孔
粗鏜、精鏜
內(nèi)孔鏜刀
φ180
游標卡尺、內(nèi)徑千分尺
臥式鏜床T68
孔
鉆擴
麻花鉆頭、擴孔鉆頭
φ25
游標卡尺
搖臂鉆床Z3050
孔
鉆
麻花鉆頭
φ13
游標卡尺
Z525Q立式鉆床
3.2 Determination of cutting amount and basic working hours
1. Front and rear end faces of coarse and semi-finishing
Material to be processed: HT200 Hardness180-200HB
Process requirements: aperture d=13mm,hole depth k=50mm,through hole,accuracy is H12-H13
Machine tool selection: vertical drilling machineZ525Q
Tool selection: use high speed steel twist drill bit
(1) decide the amount of feed
According to the reference Table 2.7, the feed rate is determined according to the processing requirements: according to the reference Table 2.7, when the processing requirement is H12-H13 precision, the hardness of cast iron is 220HBS, do=13mm, .
Since, it should be the hole depth correction coefficient , then
The feed rate is determined by the strength of the drill bit: the allowable feed rate of the drill bit strength according to Table 2.8 f = 1.0mm / r.
The feed force is determined according to the strength of the machine feed mechanism: according to Table 2.9, the axial force allowed by the Z525 drill press is 8830N, and the feed rate is 1. 2mm/r.
From the above three feed comparisons and Z585 drill press instructions, select f = 0.28 mm / r.
Since the through hole is machined, in order to avoid the hole being easily broken when the hole is about to be drilled, it is preferable to stop the automatic feed when the hole is about to be drilled and use manual feed.
The axial force during drilling,, can be found from Table 2.19. Axial force correction factor1.0, so.
According to the Z525 drilling machine manual, the maximum axial force allowed by the machine feed mechanism is .
So ≤ , then f = 0.28 is available.
(2)Drill bit blunt standard and life
According to the reference Table 2.12,the maximum wear limit of the flank is 0.5~0.9mm, and the life is T 60 min.
(3) cutting speed
According to reference Table2.13Correction factor so .
According to the Z525 drilling machine manual, the actual speed of the machine tool is , but because the selected number of revolutions is higher than the calculated number of revolutions, the tool life will decrease, so the optional feed rate is reduced by one-level, that is, f=0.22mm/r, ,
Cutting speed
(4)Calculating working hours
Where,I=212mm, according to the reference Table 3.26, the amount of cut and the amount of cut
so
21
Chapter 4 Drill six small hole fixture design
4.1 Positioning scheme design
The bearing housing of this time is a special fixture for six φ13 holes on the large end face. Since the center large hole φ180 has been processed, the central large hole can be selected as a main positioning reference, and the center large hole and end surface are plane. The hole positioning can limit five degrees of freedom. In order to prevent the rotation of the workpiece, a positioning reference for restricting the inversion can be made in the groove of the upper end surface or the right end surface of the workpiece. This way the entire workpiece will be fully positioned.
4.2 Positioning error analysis
In this special fixture for drilling 6-φ13 holes, the main positioning reference is mainly based on the center large circular hole φ180 and the large end face. The error analysis of the main positioning can be analyzed, and it is known that the positioning method of one hole side is as follows.
When any side is in contact (pin is placed vertically)
:Minimum clearance between positioning hole and positioning pin
This time, one hole and one plane are positioned in the form of any side contact, and the positioning error formula is contacted by any side.
The tolerance of the hole of the part hole φ180H7 is φ180,so=0.04
The φ160 tolerance of the positioning axis is φ100,so=-0.04
4.3 Calculation of cutting force and clamping force
(1) Cutting force calculation
This time is the cutting force of drilling 6-φ13 hole, which is calculated according to the maximum cutting force when drilling φ13.0.
Cutting force formula for drilling
:Drill diameter is
:Axial cutting force
:Feed per revolution
:Correction factor
(2) Calculation of clamping force
The clamping mechanism adopts two moving pressure plates to clamp the unprocessed surface of the fork. According to the surface clamping form, the clamping mode is a moving plate type clamping mode.
From the analysis of the clamping condition of the whole pressure plate, the clamping force analysis of this pressure plate is as follows
It can be seen that the driving force is that the blessing force is that the relationship between the whole clamping force and the driving force is as follows
:Primary power Nmm
:Actual clamping force required N
:Equivalent friction radius between the end of the screw and the workpiece mm
:Half of the thread diameter
:Thread angle
:Friction angle between the end of the screw and the workpiece
:The equivalent friction angle of the helical pair,.Where is the friction angle of the helical pair, which is the half angle of the thread
:In addition to the efficiency of the screw mechanism, the general index is 0.85 to 0.95, and the selection is 0.88.
The motive force in this clamping device is 2810N
The screw diameter of the bolt part of this selection part is 24, that is, the bolt of M24 drives the movable top pin. According to the third edition of the Machine Tool Fixture Design Manual (the same below), the spiral in Table 1-2-20 The equivalent friction radius of the secondary, the adjustment support of this time is the circumferential line contact, the diameter of the thread is M24, then the equivalent friction radius of its helical pair is,Since the M24 threaded pin is selected, select the coarse thread of M24×3, and look up the ordinary thread angle of Table 1-2-21, so that the half of the thread diameter is= 11.02, its thread angle,Since the surface of the top pin and the contact hinge support block are the friction of the steel piece, the general friction coefficient is selected as,Then the friction angle between the end of the screw and the workpiece is,This time chose.Look up the equivalent friction angle of the spiral pair in Table 1-2-22.
This can be known as the driving force
The clamping force of this time is
4.4 Guide design
The guiding components for drilling are usually used with fixed drill sleeves, interchangeable drill sleeves, quick-change drill sleeves, special drill sleeves, etc. This time, the drill sleeve can be used. When using the replaceable drill sleeve, it is necessary to use the drill sleeve. The guiding element of the bushing and the drill sleeve screw, the diameter of the drill hole is φ13, then the diameter of the inner hole of the replaceable drill sleeve is also selected as the replaceable drill sleeve of φ13. For the "machine tool fixture design manual", select the inner hole. The drill collar with a diameter of φ13 is JB/T8045.2-1999, and the bushing for the drill collar with a diameter of φ12 is a bushing for the drill collar with a diameter of φ13. The standard number is JB. /T8045.4-1999, the drill sleeve screw used is M6, the standard number is JB/T8045.5-1999, the tolerance band between the replaceable drill sleeve and the bushing for the drill sleeve is H7/k6, and the bushing for the drill sleeve The tolerance zone between the drill template and the drill template is also H7/k6
4.5 Clamping operation description
This time, we drilled six φ13 hole special fixtures. The clamping method uses a screw clamping mechanism. The two moving platens are used to clamp the workpiece. When disassembling, we only need to lock the moving platen. The nut is loosened, and then the bearing housing can be removed or installed. However, the support seat of the support plate that restricts its flipping in the side groove needs to loosen the screw locked on the clamp to adjust the support seat. It is convenient to take out or install the workpiece.
The assembly drawing of the entire fixture of the six holes of the bearing housing is as follows.
Conclusion
The fixture design process is a comprehensive system knowledge summary. Throughout the process, I feel that the power of knowledge is great, and a lot of knowledge points that were not noticed in the previous textbooks are reflected in this design process. . At first, I didn’t know much about the design. I didn’t know how to do it. I slowly went through the previous period of inquiry knowledge and the analysis of the case, especially the case of these class parts. After a detailed understanding and analysis, all kinds of fixtures in this area have basically certain grasps, familiar with various structural steps and design processes, and also go to many fixture design bases to understand fixtures. The physical structure, the details of the installation position of the various fixture parts, as well as the specific action process of these parts during the processing, through the study with the field masters, slowly have a certain concept It is. In fact, the whole fixture design is mainly to have a detailed process, to guide how to follow the steps, then to analyze the process requirements of the products you design, to know what specific needs, so that you can better determine the processing The plan, and then the calculation of the relevant parts of the fixture, is followed by the structure of the fixture drawn through the drawings, and through a period of use, the application of the software is also very familiar, these are learned in the graduation design In general, I feel a lot of gains.
References
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