Manufacturing process of driven shaft

Contents

Contents Sheet

Introduction

1 General part

1.1 Justification of the form and type of production

1.2 Justification of initial procurement selection

1.3 Calculation of machining allowances

2 Process Part

2.1 Process route and selection of bases

2.2 Operational justification and description

part workpiece machining process

2.3 Calculation of cutting modes of main operations and

technical time rationing

2.4 Unit Dimension Analysis

3 Design part

3.1 Calculation of accessory

3.2 Calculation of component cutting forces

3.3 Calculation of clamping device and structural

drive parameters

3.4 Calculation of installation error

4 Conclusion

5 List of used literature

COURSEWORK

in the discipline "Automotive Technology"

Topic: "Develop a processing process

driven shaft of cylindrical reduction gear box "

Introduction

At the current stage of development, the main tasks considered by the engineering technology are such tasks as: the creation of fundamentally new technologies that allow you to repeatedly increase productivity; transition from the development of individual machines and technologies to the development and application of technological complexes; application of automatic process design system.

The topic of coursework is the design of the process of processing the output shaft. The purpose of the course work is to consolidate the knowledge gained during the study of the subject "Engineering Technology" and acquire skills in the development of the technological process of processing the part based on them .

General part

This shaft is used in a cylindrical reduction gear and serves to transmit rotational motion.

As the initial data for the development of this course project, I was given the output shaft drawing, in this drawing I identified the following inaccuracies:

1) Surface roughness 7 and 8 is not indicated.

2) Unspecified roughness is given in Rz system.

3) Incorrect specification.

4) The quotas on the lengths of the key slots (17 and 19 surfaces) are incorrectly indicated.

5) The tolerance for the free diameter (6 surface) is too rigid.

6) The depths of the key slots (surface 18 and 20) are incorrectly specified.

7) Numerical values of deviations (all surfaces) are not specified.

8) The fillet radius (8 surface) is incorrect.

All the above mentioned drawbacks are taken into account in the revised drawing

Qualitative evaluation of processability

1) This shaft can be treated with pass-through cutters that increase processing efficiency.

2) Diametrical dimensions of shaft necks decrease to ends.

3) Indicators of base surfaces 3, 7, 13, 15 ensure accuracy of installation, processing and control.

Quantification of processability

1) Material utilization rate will be calculated in item

2) Average Part Quality

IT = (IT x n )/ n ,

where IT is the quota of surfaces;

n is the number of surfaces with the same quota.

IT = (6x4 + 9x2 + 12x5 + 14x7 )/18 = 11

3 Average part roughness

Ra = (Ra x n )/ n

where Ra is surface roughness;

n is the number of surfaces with the same roughness.

Ra = (1.25x6 + 3.2x2 + 10x10 )/18 = 6.3

The part is quite technological, it is allowed to use high-performance processing modes.

1.1 Justification of the form and type of production.

Production type - a classification category of production, distinguished by the characteristics of the breadth of the nomenclature, regularity, stability and volume of production of products.

The accepted output (N = 3000 pcs/year) corresponds to the average production (CC) type.

The production form is in-line - the designed part is produced at a specially created enterprise for this purpose. In this form, the workpiece is in motion during manufacture having a certain stroke value.

The number of parts in the batch to run simultaneously is

where a = 12 days is the start-up frequency for CC production.

1.2 Justification of initial procurement selection

Part weight 6.9 kg

We choose 2 types of procurement: stamping, rolled stock.

Output: to obtain a workpiece, we select stamping,

since this method is more economical.

Define allowances and dimensions as per Table:

Table 3.2 - Allowance and dimensions for stamping

Service assignment of surfaces

3. Calculation of machining allowances

Source Data:

Part name: gimbal joint attachment flange

Material: Steel 12XH3

Elementary surfaces for allowance calculation - external surfaces d55h9 and d50H11.

For other transitions, the values are determined depending on the reached quota during this transition.

Draft turning. Value of residual spatial deviations is determined by equation:

Calculated values of surface location deviations are entered in column 4 of Table.

Minimum allowances for diametrical dimensions for each transition are determined by constraints:

where Rzi1, h i1, i-1 are respectively the height of irregularities, the depth of the defective layer and the surface location error obtained at the previous transition.

Ei error of workpiece installation at this transition.

For draft turning:

The calculation of the smallest dimensions by technical transitions begins with the smallest dimension of the part according to the design drawing using the initial data:

The tolerance for manufacturing intermediate dimensions Td is a table value and is determined depending on the quota obtained at this transition.

Accepted (rounded) dimensions by transitions determine the rounded values ​ ​ of the corresponding dimensions.

Check correct calculations:

4,6 - 3=1,9 + 0,300

1,6=1,6

calculation is correct.

Process Part

2.1 Process route and selection of bases

2.3 Calculation of cutting modes of main operations and

technical time rationing

The metal cutting mode includes the following elements that define it: cutting depth t, mm; supply S, mm/v; cutting speed V, m/min and number of revolutions of machine spindle n, rpm.

The allowance is divided into draft, finish and finishing. The allowance value is determined depending on the obtained during the previous treatment: the value of the defective layer; surface microgeometry; part shape errors.

The amount of feed is assigned depending on: the type of part, stiffness, strength, state of the surface layer; strength, stiffness, wear resistance of AIDS system.

The largest supply allowed by these limiting factors is accepted.

The actual supply is accepted according to the passport data of the machine closest to the design supply.

Cutting speed is determined by empirical power dependencies:

where Vt is cutting speed at selected period of resistance of cutting tool equal to T (min);

t - cutting depth, mm;

S - supply, mm/v;

x, y are degree indicators, respectively, at cutting depth and feed; - a constant value depending on a number of factors.

To determine the calculated number of spindle revolutions, the design dimensions are selected depending on the treatment method of either the surface to be machined or the tool.

The number of revolutions of the part at the assigned cutting speed is determined by the calculated diameters

Then, the actual number of revolutions according to the machine passport closest to the design one is accepted.

After determining the cutting speed, the empirical dependencies of the component cutting forces of the operations Pz, Py, Px, as well as the torque Mkr are calculated.

Once the cutting forces are determined, the required power of the machine is determined. The effective power on the Ne cutter and the required power on the Npr machine drive are determined.

After calculating the power on the Npr drive, it is compared with the electric motor power of the selected machine Nst and dividing the first value by the second value, a power utilization factor of the machine is obtained (¼ m):

Source Data:

Material - 12HNZ Steel.

Minimum roughness - Rz 3.2.

Billet - stamping.

1) Operation 040 Vertical Milling.

Mill the runner to a size of 11.2 flush with the main surface.

Machine 6D91

Tool - end cutter equipped with screw hard alloy plates GOST 2053775, Ø20 mm, number of teeth z = 4.

Allowance t = 12,511,2 = 1, 3mm

Initial value of feed at finishing milling is its value per one revolution of cutter, from which value of feed per tooth is calculated for further use.

2.4 Dimensional analysis of the unit.

A dimension chain is a collection of dimensions of parts (parts) that form a closed loop and participate in solving a given problem. The chain consists of an initial closing link (set from the very beginning and obtained after assembly of the unit) and component links, which, depending on the effect on the initial closing, are increasing and decreasing.

Two dimension chains for analysis are proposed for calculation: a driven shaft assembly located in the housing, and a driving shaft assembly.

First, the dimension chain that includes the driven driven shaft assembly is analyzed. During operation, the shaft rotates in bearings, which on one side abut against the shoulders of the gear and shaft, respectively, and on the other side are limited from axial movement by an annular nut and a spacer sleeve. During operation of the mechanism heat is generated, which causes expansion of metal elements of the structure. For proper and long-term operation of the bearings and, accordingly, the entire assembly, it is necessary to provide a thermal gap between the ends of the bearings and the thrust rings. For ease of calculation, we believe that the clearance in the right bearing is selected, and the desired value is the clearance in the left bearing. Then the determined value will be equal to the sum of the thermal clearances in the bearings of the output shaft.

We choose the method of achieving the accuracy of the initial-closing link - the method of complete interchangeability (MPA). The dimension chain is calculated using the maxmin method.

Dimensional analysis is carried out using the following algorithm:

1. The purpose of the dimensional analysis is to provide thermal clearance between the end face of the left bearing of the driven shaft, pos.26 and the end face of the drive shaft gear, pos.27.

Clearance value is determined by formula

a = 12 × 10-6 × t × l + 0.15 = 12 × 106 × 75 × 430 + 0.15 = 0, 537mm,

where t = 75 ° C is the maximum temperature drop of the shaft;

l = 430mm - length of shaft section enclosed between bearings

We need to obtain the following data: dimensional chain A; AΔ = 0.5 mm; δAΔ = 0.5 mm; coordinate of tolerance middle Δ0AΔ = 0mm; = + 0, 25mm; = 0, 25mm.

2. Therefore, the gap itself will be the initial closing link.

This chain is the shortest and forms a closed loop, and each part of the chain enters it with one dimension. In total, 12 links are obtained.

4. We define increasing (as their size increases, the size of the initial closing link increases) and reducing (accordingly, as its size increases, the size of the initial closing link decreases) links. Based on the definitions of the types of component links, only the body will be an increasing link, and all other elements of the chain will be reducing.

5. The transfer relation of the making links for flat linear dimensional chains ξ=±1.

6. You can now plot the dimension chain

Nominal value of closing link is determined by formula

where n is the number of increasing links, m is the total number of links in the chain.

Tolerance of closing link

which is significantly greater than the desired value. Continue the calculation to populate the PivotTable.

Rounded to = 1.07mm.

Lower deviation of initial closing link

Upper deviation of initial closing link

When you draw up a summary table of the results of the calculation of the dimension chain = 0.097mm (for the tolerance obtained by the calculation) and the coordinates of the midpoints of the tolerance fields equal to half of the corresponding tolerances.

We obtain a gap with parameters AΔ = mm. The accuracy of the closing link is quite achievable according to MPV in medium-term production conditions, but does not meet the specified conditions.

We solve the same problem by the method of incomplete interchangeability (MHV).

I consider the denominations and tolerances of chain links known and obtained earlier.

For MNE calculation we enter the following most optimal values:

- risk coefficient tΔ = 3 at 0.27% scrap during assembly;

is a coefficient characterizing the critical law of scattering of values, γ = 1/3 (for the law of normal distribution - with well-established technology).

The initial closing link will then be AΔ =, which is practically equal to the desired value.

It follows from the calculation that the accuracy of the initial closing link is achieved by the MNE with 0.27% marriage and the breakdown of the average tolerance by the components of the chain (up to economically achievable under the conditions of MOP production).

Now we analyze the second dimension chain - the intermediate shaft assembly, the axis of which coincides with the plane of the housing connector and the gearbox crankcase.

The method of achieving the accuracy of the initial closing link (MPV) and the calculation of the dimensional chain ("maxmin") is similar to circuit A.

1. The task of dimensional analysis is to provide a clearance between the ends of the bearing and the ring during assembly of the assembly, within the limits of 0.5... 0, 6 mm (dimension chain B).

Minimum gap a = 12 × 106 × t × l + 0.15 = 12 × 106 × 75 × 472 + 0.15 = 0, 575mm,

2. Therefore, the gap itself is the initial closing link, and the nominal size (BΔ) and the lower deviation (), respectively, will be two and zero.

4. Increasing and decreasing units. The enlarging links will be the gearbox housing, sealing gasket, sleeve flange and recess in the cover, and all others will be reducing.

5. The transfer relation of the making links ξ=±1.

6. You can now plot the dimension chain

7. Nominal values of chain links and their tolerances. From the factory drawings it follows:

Then the nominal value of the closing link

where n is the number of increasing units;

m is the total number of links in the circuit.

Tolerance of closing link

, which is almost equal to the required value.

9. The lower deviation of the initial closing link is determined by the formula

Upper deviation of initial closing link

We obtain a gap with parameters BΔ = mm. The accuracy of the closing link is achievable in medium-term production conditions, but does not satisfy the specified conditions.

When creating a summary table of the results of the calculation of the dimension chain, you will need the average value of the tolerance field of the constituent links δsr = = = 0.093mm (for the tolerance obtained by the calculation) and the coordinates of the midpoints of the tolerance fields equal to half of the corresponding tolerances.

We solve the same problem by the method of incomplete interchangeability (MHV).

I consider the denominations and tolerances of chain links known and obtained earlier.

For MNE calculation we enter the following most optimal values:

- risk coefficient tΔ = 3 at 0.27% scrap during assembly;

is a coefficient characterizing the critical law of scattering of values, γ = 1/3 (for the law of normal distribution - with well-established technology).

values.

It follows from the calculation that the accuracy of the initial closing link is achieved by the MNE with 0.27% marriage and the breakdown of the average tolerance by the components of the chain (up to economically achievable under the conditions of MOP production).

Design Part

3.1 Calculation of accessory

The main calculations of the machine tool are:

1. Calculation of component cutting forces;

2. Calculation of fixing force (s);

3. Calculation of clamping device and drive design parameters;

4. Calculates installation error, position coordinates of cutting tool guides.

3.2 Calculation of component cutting forces

The milling operation requires the circumferential force Pz, axial P0, Ps feed, vertical Pv, and radial Py.

3.3 Calculation of clamping device and drive design parameters

The equation of the combined clamping device is as follows:

From these formulas we find the necessary values ​ ​ of force (P) and movement (S) transmitted from the power drive to elementary mechanisms.

Number of elementary mechanisms i = 1;

Transmission ratio of forces a = 5;

Displacement ratio i = 0.158

I.e. to secure the blank, the piston of the pneumatic cylinder must move a distance of 32 mm and develop a force of 442.2 N.

The force on the rod of the pneumatic cylinder is according to the formula:

Since at small values the cylinder diameter decreases its efficiency, we take the cylinder diameter D = 80 mm.

3.4 Calculation of installation error.

Installation error for machine tools is determined by formula:

Machine installation error:

Since the permissible error is greater than the actual error, this device meets the requirements of accuracy of the size.

Conclusion

During the course work, the technological process of processing the output shaft part was developed. On the basis of the knowledge obtained, the type of production, the structure and method of obtaining the workpiece, the technological processing route, the processing plan and the operating technology were developed and selected.

List of literature used

1. Antonyuk V.E., Korolev V.A., Basheev S.M. Designer's handbook on the calculation and design of machine tools. - Minsk: "Belarus," 1969 - 390s.;

2. Gorbatsevich A.F., Shkred V.A. Course design on mechanical engineering technology - 4th edition revised and supplemented. -Mn. High. sq., 1983256 s.

3. Anuryev V.I. Ed. I.N. Zhestkova. Reference book of the designer-mechanical engineer. T. 2. - 8th ed., Redesign. and additional. - M.: Engineering, 2001. - 901s., il.;

4. Gorbatsevich A.F., Shkred V.A. Course design in mechanical engineering technology: Text. manual for mechanical engineering. special. universities. - 4th ed., Conversion. and additional - Mn.: Vysh. school, 1983. - 256s., il.;

5. Kosilova A.G., Meshcheryakov R.K. Handbook of the technologist-machine engineer. In 2 t. T. 2. - 4th ed., Conversion. and additional - M.: Engineering, 1986. - 496s., il.;

6. Kuznetsov Yu.I., Maslov A.R., Baykov A.N. Tooling for a CNC machine: Handbook. - 2nd ed., Redesign. and additional - M.: Engineering, 1990. - 512s.: il.;

7. Panov A.A., Anikin V.V., Boim N.G. and others. Under the commonly. Ed. A.A. Panova. Cutting of Metals: Technologist's Handbook. - M.: Engineering. 1988. - 736s.: ill.; 3. Sorokin V.G., Volosnyakova A.V., Vyatkin S.A. and others. Marochnik of steels and alloys. - M.: Engineering, 1989. – 640 pages.