Please help me find some questions about the NC exam.

Examination questions of NC machining and programming (6)

I. Multiple choice questions (2'X2 1)

1. The left compensation direction of the tip radius is specified as follows.

A, the workpiece is located on the left side of the tool when viewed along the direction of tool movement; B, the workpiece is located on the left side of the tool when viewed along the movement direction of the workpiece;

C, looking along the direction of workpiece movement, the cutter is located on the left side of the workpiece; D, along the direction of tool movement, the tool is located on the left side of the workpiece.

2.G00 instruction moving speed value is.

A, machine tool parameter specification; B, numerical control programming; C. Name of operation panel

3. Use φ 12 tool to finish rough machining of the contour. If the finishing allowance is 0.4, the rough machining offset is 0.

a、 12.4； b、 1 1.6； c、6.4

4. After performing the following procedures, the cumulative feeding pause time is.

n 1g 9 1 G00 x 120.0y 80.0

N2 G43 Z-32.0 H0 1

N3 g 0 1 Z-2 1.0 f 120

N4 G04 P 1000

N5 G00 Z2 1.0

N6 X30.0 Y-50.0

n7 g 0 1 Z-4 1.0 f 120

N8 G04 X2.0

N9 G49 G00 Z55.0

N 10 M02

A, 2 seconds; B, 3 seconds; C, 1002 second; D, 1.002 seconds

5. The fixed cycle function of CNC machining center is applicable to.

A. machining curved surface shape; B, plane shape processing; C, hole-making processing

6. On the CNC milling machine, after performing the following procedures with φ20 milling cutter, the diameter of the processed arc is.

n 1 G90 g 17g 4 1 x 18.0y 24.0 M03 H06

N2G02x74.0y32.0r40.0f180 (cutter radius compensation offset value is φ20.2).

a、φ80.2； b、φ80.4； c、φ79.8

7. When the spindle of CNC machine tool rotates forward at 800 rpm, its instruction should be.

a、M03 S800b、M04 S800c、M05 S800

8. There are many kinds of CNC machine tools, which can be divided into two parts if they are divided according to the machining trajectory.

A, two-axis control, three-axis control and continuous control; B, point control, linear control and continuous control;

C, two-axis control, three-axis control and multi-axis control

9. There is a mechanical origin on the NC machine tool. When the machine tool leaves the factory, you can set the distance from this point in the direction of the feed coordinate axis to the zero point of the machine tool coordinate. This point is called.

First, the zero point of the workpiece; B, machine tool zero; C, machine tool reference point

10. The coordinate axis of the rotary motion around the X axis is.

A, an axis; B, b axis; C and z axes

1 1. Positive compensation of tool length is an instruction, negative compensation is an instruction, and cancellation of compensation is an instruction.

a、G43b、G44c、G49

12. When replacing processed products, ordinary machine tools are realized by _ _, automatic machine tools and copying machine tools are mainly realized by _ _, and CNC machine tools only need to be realized by _ _.

A, reprogramming B, changing rules, directly controlling C manually, and changing cam copying equipment.

13. Machining centers with small tool magazine capacity generally adopt the tool magazine form, while machining centers with large tool magazine capacity mostly adopt the tool magazine form. Code the cutter or cutter seat, and select the cutter according to the code.

A, chain B, drum C, sequential knife selection D, optional knife selection

14. deep hole machining in drilling and boring cycle needs intermittent feed mode, which should be a fixed amount q for each tool withdrawal to a safe plane. ..

a、G73 B、G83 C、G74 D、G84

One, two, drawing questions (2X6)

1. 1. Drawings show several technical routes (unidirectional cutting, bidirectional cutting, circumferential cutting, etc.). ), mark the milling interval and explain how to determine this parameter.

2. The figure shows the machining route of fixed cycle drilling and boring, and explains the meaning of each route segment when it is applied to the machining of screw counterbore seat (G82).

Three. Short answer questions (23)

1. What is the significance of program verification and no-load debugging before formal processing? What kind of inspection can be carried out in the mechanical locking state? (8)

2. What is the alignment point? How does the choice of cutter location affect programming? (5)

3. What are the main contents of NC machining programming? (5)

4. What kind of tool path definition should be made for the curved surface parts shown in the figure, from blank to part size? (5)

Four, programming questions (23 points)

1. To process the parts shown in the figure below, it is necessary to determine the processing sequence, set the processing parameters, select and adjust the cutter, compile and fill in the NC process card and manually write the NC program, input the program code, clamp the workpiece and cutter, set the cutter and operate the machine tool for cutting.

Reference answer

First, first, multiple choice questions

1.C 2。 A 3。 C 4 explosive B 5。 C 6。 A seven. An eight. B 9。 C 10。 A 1 1。 ABC 12。 BCA 13。 Bad 14. barium

Second, drawing questions

2. The fixed cycle action sequence of drilling and countersinking can be decomposed into:

(1)X and Y axes are quickly positioned in the center of the hole.

(2) Quickly run to the safe height plane (R plane) near the hole.

(3) drilling (drilling) to the bottom surface of the countersink

(4) Pause at the bottom of the countersink.

(5) Quickly return to the safe plane height or the initial plane height.

Third, short answer

1. The significance of pre-processing program verification and no-load debugging lies in:

(1) is used to check whether there are syntax errors in the program. A considerable part can be analyzed and judged by the alarm number.

(2) Used to check whether the walking trajectory of the program meets the requirements. From the graphic tracking, we can see the approximate trajectory shape. In order to further check the dimensional accuracy, we need to view and analyze the coordinate data of each node with a single button.

(3) Used to check whether the clamping position of the workpiece is reasonable. This is mainly judged from whether the stroke control of the workbench is out of bounds and whether the position interference and overlap between components will occur in the walking trajectory.

(4) It is used to arrange some process instructions reasonably through debugging, so as to optimize and facilitate the actual processing operation.

When the machine tool is locked, it is mainly used to check the grammatical errors of the program and check the trajectory graphics.

2.2. The tool alignment point refers to the starting point of the movement of the tool relative to the workpiece during NC machining. This starting point is also the starting point of the program when programming. Reasonable cutter point selection, convenient for mathematical processing and simple programming; Easy to align on the machine tool; It is easy to check during processing, resulting in small processing error.

3. The main contents of NC machining programming include: analyzing part drawings, determining process flow and route, calculating tool path coordinate values, writing machining programs, inputting programs into NC system, verifying programs, and trying to cut the first piece.

4. Starting from the blank, the illustrated curved surface parts shall be defined as follows:

(1) Cutter or fillet cutter, the curved surface shall be excavated and roughly cut, and the finishing allowance shall be reserved.

(2) ball end mill, parallel plane rough cutting.

(3) finishing spherical cutter, contour or parallel surface.

(4) Ball-end milling cutter, finish machining of steep slope and shallow plane.

(5) Little ball end mill, corner clearing of surplus materials and intersection lines.

Fourth, the programming problem.

O000 1

g92x 60z 120；

t 0 10 1；

G90G00X35Z5

M03S600