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Preparation: Machine, Cutting Tools, Measuring Tools, Fixtures and Workpieces According to the Requirements of the Box Detail to Be Machined.

3.2. Sequence of processing steps


TT

Sequence

Diagram

Technical requirements

1

Step 1:

Tool holder and workpiece


- The knife tip must be level with the center of the part.

- Workpiece mounted on the chuck

4 jaws are tight enough, need to adjust the jaws appropriately so that the block is not too far off the center of the machine

- Rotate the chuck by hand then observe the gap to adjust.

position the workpiece

2

Step 2:

Convenient

first party

n = 300-600 rpm; S= 0.1mm/rev t = 0.5mm

Rough turning to size L52.

3

Step 3:

Second side face



n= 300-600 rpm; S= 0.1mm/rev t = 0.5mm

Rough turning to size L50.

Maybe you are interested!

Step 4:


Reach L100 size


Rough and



essence

face




head





n


=


400-500


rpm;


t


=


1mm;


S


=




0.15mm/rg


5

Step 5:

Rough and finish turning of flat surfaces




n = 400-600 rpm; t = 0.25mm; S = 0.05mm/vg

Adjust the tailstock to ensure

Concentricity between the headstock and tailstock.

6

Step

6 :




Rough and



pure

face



plane

still



again





n = 400-600 rpm; t = 0.25mm; S =



0.05mm/rg

4









Step 6: Check


Overall check of technical requirements according to drawing requirements



4. Self-study guide

a. Selecting a fixture to machine the flat surface of the box part on a universal lathe.

b. Methods of machining the plane of box details.

Lesson 6.2. Turning holes on box-shaped parts (06 periods)


A. Teaching facilities and equipment

1. Means

Lesson plans, outlines, chalk, projector, drawings, ...

2. Equipment


T

T

Name and specifications of the device,

tools; raw materials, consumables

Single

taste

SL

Note

Additional

1

Equipment, tools (for 01 student)






- Universal lathe; fixture

Female

01




- Cutting tool grinder (shared)

Female

01




- Measuring tools: 1/50 caliper, ruler

Set

01




- Cutting tool: external turning tool (curved tip,

shoulder cutter: T15K6 or P18), hole cutter

Set

01



2

Raw materials, consumables (for 01 student)






- CT45 steel (100x 100 x50)mm

Female

01

Continued use


- Engine oil

Liter




- Cleaning cloth

Kg

0.2

Cancel


3

Other






B. Implement the lesson

1. Lesson objectives

After completing this lesson, students will be able to:

About knowledge

- Know the method of mounting box-shaped parts on a universal lathe to make holes

- Know the method of turning holes on box-shaped parts

About skills

- The fixture ensures positioning and clamping of the part to facilitate the hole making of the box-shaped part.

- Turning the hole surface on the block detail ensures technical requirements.

About attitude

- Be serious and proactive in learning and practicing industrial production style. Ensure labor safety and environmental hygiene.

2. Lesson content

2.1. Turning holes on box details

Hole turning of box-shaped parts on a universal lathe is often performed for small-sized boxes in the following cases:

1) Turning holes and 01 plane to make a standard for positioning the next machining steps (operations) of the box-shaped part

Applicable to workpieces of shape and size that allow positioning and clamping in a chuck (3 or 4 jaw chuck; flat chuck) (Figure 6.3)

Figure 6.3 Mounting the part on the flower tray to turn the hole and the end face

- Position and clamp firmly by the outer surface of the workpiece

- Use fixture checking methods: flat checking of the end face, parallel checking (hole center parallel to machine center) and center-matching checking (hole center coincides with machine center).

2) Turning the mounting hole face (done when the box part has been machined on the standard face, can be mounted on a flat chuck, 4-jaw chuck or fixture, ...), often used when turning the hole of a simple shaft support.

Applicable to workpieces that have been machined on all or some of the outer surfaces, ensuring parallelism and perpendicularity between the surfaces.

Figure 6.4 Flower tray fixture and adjusting bracket for mounting box details

- Positioning by 01 plane and head surface.

- Use fixture checking methods: flat checking of the end face, parallel checking (hole center parallel to machine center) and center-matching checking (hole center coincides with machine center).

2.2. Choose a knife

Select similar to selecting the tool when turning the inner cylindrical surface

2.3. Select cutting mode

Select similar to when turning inner cylindrical surface with non-eccentric box part; for box part with eccentric hole, select similar to when turning eccentric hole.

2.4. Implementation sequence

2.4.1. Preparation: machine, cutting tool, measuring tool, fixture and blank according to the requirements of the box part to be machined.

2.4.2. Workpiece holder and tool holder

Conforms to the requirements of the selected box detail machining technology.

2.4.3. Adjusting and operating the lathe

2.4.4. Sequence of machining steps Step 1: Turning the end face Step 2: Rough turning the hole face

Step 3: Semi-finish turning of hole face (if necessary) Step 4: Finish turning

Step 5: Check, remove blank and submit product

2.5. Types of failures, causes and prevention


TT

Failure mode

Reason

How to fix


1


Incorrect hole center position

- Wrong mark

- Check the workpiece on the machine incorrectly

- Workpiece is displaced during machining

- Precise marking

- Check the fixture before processing.

- Clamp the workpiece tightly, reduce cutting mode


2

The hole face and the end face are not square, the hole face is skewed.

with the outside

- Careless and inaccurate checking of workpieces

- Workpiece is displaced during machining

- Precise workpiece inspection


- Clamp the workpiece tightly, reduce cutting mode

3

Roughness no.

obtain

- Improper cutting mode

- Weak knife, worn knife

- Select cutting mode

- Choose the right knife

3. Organize skill training

3.1. Practice requirements

a. Drawing


b. Requirement: Finish machining a head surface from size 75 down to 74±0.1 and hole face =36, =40

3.2. Sequence of processing steps


TT

Sequence

Diagram

Technical requirements

1

Step 1: clamp the workpiece


- Mark the hole center

- Fix the workpiece according to the marking on the four-chuck chuck.

2

Step 2:

Front face


n = 300-600 rpm; S= 0.1mm/rev t = 0.5mm

The front face reaches L74 size.

3

Step 3: Drill holes


SS


n = 300-600 rpm; S= hand

Drill hole =16 L41 then drill hole =25 L41

Step 4: Roughly Convenient


n = 300-600 rpm; S = 0.2mm/rev t = 0.5mm

Lathe to size =35

5

Step 5:

Hole turning


n = 600-900 rpm; S= 0.1mm/rev t = 0.25mm

Finish the machine to 36 then check with caliper

6

Step 6:

Beveled edge


n = 300-600 rpm; S= hand

Correct chamfer

request

7

Step 7: Mounting

hole turning blank

40



Fix the workpiece so that

When rotating the chuck one round, the needle points evenly on the mark line.

4

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