Section 2 Lathe
1. The concept of lathe:
A lathe refers to a turning tool that performs feed motion on a workpiece that performs main rotational motion. Cutting machine tools.
2. Working description of lathe:
During turning, the workpiece is clamped on the chuck or tip connected to the spindle, and the spindle rotates with the chuck or tip together with the workpiece. Movement; the turning tool is mounted on the tool holder, and the tool holder moves longitudinally or transversely (the direction parallel to the bed guide rail is longitudinal, and the direction perpendicular to the bed guide rail is transverse), so that the turning tool obtains feed motion, thereby performing the feed motion on the workpiece. Turning.
3. Types of lathes:
(1) There are many types of lathes. According to their different uses and structures, they can be mainly divided into: floor-standing and horizontal lathes, vertical lathes , instrument lathes, single-axis automatic lathes, multi-axis automatic and semi-automatic lathes, hexagonal lathes, etc.
(2) Ordinary lathes can be divided into: floor lathes, horizontal lathes, saddle lathes, screwless lathes, chuck lathes, spherical lathes, etc.
4. The processing characteristics of lathes:
(1) The processing accuracy of general lathes can reach IT10~IT7, and the surface roughness Ra value can reach 1.6μm.
(2) The processing range of lathes is wide. The main processing of the rotary surface on the lathe includes: turning the outer circle, turning the end surface, grooving, drilling, boring, turning the taper surface, turning the thread, turning the forming surface, drilling the center hole and knurling, etc.
Figure 4-7: Examples of parts processed by lathes
Figure 4-6: Simplified drawing of turning processing
1. Ordinary lathes
1 .Overview:
Ordinary lathes are the most widely used type of lathes, accounting for about 65% of the total number of lathes. Because the spindle is placed horizontally, it is a horizontal lathe. CA6140 is a typical ordinary lathe.
2. Features:
Due to the wide processing range of the CA6140 lathe, its structure is complex and the degree of automation is low, so it is suitable for single-piece and small-batch production.
3. Transmission route:
(1) Main structure of ordinary lathe
The main components of CA6140 ordinary lathe include spindle box, feed box, Sliding crate, tool rest, tailstock, feed rod, lead screw and lathe bed.
1. Spindle box.
(1) The spindle box is also called the bedside box. It houses the spindle and the spindle speed change mechanism. Its main task is to pass the rotational motion from the main motor through a series of speed change mechanisms so that the spindle gets the required speed. Different speeds for forward and reverse steering.
(2) The workpiece is clamped by the chuck or mounted on the top and performs the main rotational movement with the spindle to achieve cutting processing. At the same time, the main spindle box separates part of the power to transmit the motion to the feed box.
(3) The spindle in the spindle box is a key part of the lathe. It is supported on rolling bearings and bears cutting forces during cutting. The spindle and its bearings are required to have high precision and rigidity. Once the rotation accuracy of the lathe spindle is reduced due to various reasons, the use value of the machine tool will be reduced.
2. Feed box.
(1) The feed box is also called the tool feed box. It is fixed on the left front side of the bed and is set up to adapt to different processing conditions and reasonably select the feed amount or specified pitch.
(2) The feed box is equipped with a transmission mechanism for the feed movement. By adjusting the transmission mechanism, the required feed amount or pitch can be obtained, and the movement is transmitted to the slide through the feed rod or screw. Crate.
3. Lead screw and feed rod.
(1) The screw and light rod are installed on the front side of the lathe to connect the feed box and the sliding crate, and transmit the movement and power of the feed box to the sliding crate so that the sliding crate The crate acquires longitudinal linear motion.
(2) The screw is specially designed for turning various threads. When turning other surfaces of the workpiece, only the feed rod is used instead of the screw.
4. Sliding crate. The slide box is actually the control box for the lathe's feed movement. It is equipped with a mechanism that converts the rotational motion of the lead screw and light rod into the linear motion of the tool holder. The longitudinal feed movement and transverse feed of the tool holder are realized through the light rod transmission. Movement and rapid movement, the turning tool on the tool holder is driven by the screw to move longitudinally in a straight line for turning threads.
5. Knife holder.
(1) The tool holder is used to clamp turning tools and make them perform longitudinal, transverse or oblique feed movements.
(2) The tool holder is divided into three layers.
The bottom layer is called the longitudinal slide plate, which can move longitudinally on the bed guide rails.
The second layer is the horizontal slide plate, which can move laterally perpendicular to the bed guide rail along the guide rails on the longitudinal slide plate.
The third floor is equipped with a turntable that can rotate at any angle in the horizontal plane. A small slide is installed on the turntable, which can move short distances along the guide rail on the turntable. A square tool holder is installed on the small slide plate. The turning tools are clamped on the square tool holder with screws. Up to four turning tools can be installed at the same time. When changing tools, loosen the handle and rotate the square tool holder to move the required turning tool to the working position. The handle must be tightened to fix the square tool holder during work.
6. Tailstock (tailstock). When processing slender workpieces, a tip is installed in the tailstock to support one end of the workpiece. If the tip is removed and a drill and other tools are installed, drilling, reaming and tapping on the lathe can be achieved.
7. Bed.
(1) The bed is mounted on the left and right legs to support the three boxes (spindle box, feed box, slide box) and two bars (light rod, screw) on the lathe (Tool holder, tailstock).
(2) The left leg of the machine tool is equipped with a lubricating oil tank and a driving motor. There is a coolant tank and coolant pump on the right bed leg.
(2) Technical specifications of CA6140 lathe
The technical specifications of machine tools are technical data that reflect the working performance of different varieties and categories of machine tools, and are an important reference for selecting machine tools. The technical specifications of general machine tools consist of five parts:
1. Technical parameters. It is mainly a parameter that reflects the processing capability of the machine tool, including the main parameter and the second main parameter.
2. Machine tool working speed series and adjustment range.
3. Machine tool main motor power.
4. Overall dimensions of the machine tool.
5. The weight of the machine tool.
Table 4-5 Main technical performance of the CA6140 ordinary lathe
Serial number item
l Rotation diameter of the workpiece on the bed…………………… ……………… 400mm
Center height……………………………………………………………… 205mm
Workpiece length…………750mm, 1000mm, 1500mm, 2000mm
Spindle inner hole diameter………………………………………… …………48mm
Spindle front end taper………………………………………………………………………… Mohs No. 6
2 Spindle speed, forward rotation, level 24…………………l0~400 rpm/min
Reverse rotation, level 12……………… l4～1580 rpm
Feed vertically (level 64)……………………0.028mm～6.33mm/rev
Horizontal (level 64) ………………………0.014mm～3.16mm/rev
Longitudinal rapid movement speed of slide plate and tool holder………………………………4 meters/ Minutes
3 Main motor power……………………………………………………7.5 kilowatts
Slide plate quick-moving motor………… ………………………………………………0.37 kilowatts
4 Machine tool outline dimensions (length ………………2 668 >
2. Vertical lathe
(1) Overview:
The main features of the vertical lathe are that the spindle is upright, the workbench is in a horizontal plane, and the workpiece is clamped On a large worktable that rotates driven by a spindle.
(2) Classification:
Vertical lathes are divided into single-column and double-column types. The processing diameter of single-column vertical lathes is smaller (diameter less than 1600mm); The double-column vertical lathe has a larger processing diameter (the processing diameter of the vertical lathe exceeds 2500mm) and can clamp heavy workpieces weighing 80t.
(3) Motion description: The workpiece is mounted on the workbench and driven by the spindle. The feeding movement is realized by the vertical tool rest 3 and the side tool rest 4.
Since the workpiece is mounted on a horizontal workbench, it is more convenient to clamp the workpiece. The quality and cutting force of the workpiece are borne by the rotary guide rail between the workbench and the base, which reduces the load on the spindle and its bearings. The work is stable, it is easier to ensure machining accuracy, and the working accuracy of the lathe can be guaranteed for a longer period of time.
(4) The main features of vertical lathes are:
1. The workbench is in the horizontal plane, so the installation and adjustment of the workpiece is more convenient and safe.
2. The workbench is supported by guide rails, with good rigidity, stable cutting, and good stress-bearing condition of the spindle.
3. There are several tool holders, which can be used for cutting with multiple tools and can quickly change tools. The processing accuracy of the vertical lathe can reach IT8~IT7, and the surface roughness Ra value can reach 1.6μm~0.8μm. .
3. Hexagonal lathe
(1) Features: No screw and tailstock, but a hexagonal tool holder (turret tool holder).
(2) Motion description:
On a hexagonal lathe, all the tools used can be installed on the lathe in advance, and their position and size can be adjusted; the stroke end position of each set of tools , which can be controlled by the stop on the machine bed. After the machine tool is adjusted, there is no need to repeatedly load, unload and adjust the tool when processing each workpiece. Therefore, the operation is convenient and rapid, which can save auxiliary time and achieve high productivity.
(3) Classification:
Hexagonal lathes are divided into vertical turret lathes (Figure 4-12) and return lathes (Figure 4-13).
The hexagonal tool holder rotates around the horizontal axis is called a return lathe.
(4) Features:
When processing the outer circle with a hexagonal lathe, the accuracy can reach IT11~IT8, and the surface roughness Ra value can reach 3.2~1.6μm. When processing holes, the accuracy It can reach IT7, and the surface roughness Ra value can reach 0.8μm.
Example 6? Multiple-choice question Among the following processes, which can be completed on an ordinary lathe ( )
A. Boring
B. Drilling
C. Milling keyway
D. Grinding outer circle
E. Knurling
Answer: ABE
Example 7? Single choice question (2008) Among the following statements about the use of lathes, the incorrect one is ( ).
A. No matter what workpiece is processed, the spindle must be used
B. If the screw mosquito is not processed, the screw is not needed
C. Regardless No matter what workpiece is processed, the tool must be installed on the tool holder
D. When turning the outer circle of disc-type parts, there is no need for a tailstock
Answer: C
Example 8? Single-choice question Among the following statements about lathes, which one is incorrect ( ).
A. During cutting, the spindle always bears cutting force
B. The screw is specially designed for turning various threads
C. Slide The board box is the control box for the lathe's feed motion
D. The feed box is equipped with a mechanism that converts the rotational motion of the lead screw and light rod into the linear motion of the tool holder
Answer: D
[Comprehensive 1]
(6 points out of 10) A lathe is in use in a certain unit. Its model is CA6140×1500. It has been used for two years. The original version of the lathe The purchase price is 60,000 yuan. Currently, the performance of the new lathe of the same model has not changed, but the market price has dropped to 45,000 yuan. Through on-site appraisal of the wear degree and accuracy of the main components of the lathe, the appraiser believed that the lathe's visible wear degree was 20%.
Question:
(1) What are the first and second main parameters of the lathe? How many are they?
(2) What are the main components of the lathe? What is the main motion?
(3) What kind of invisible wear does this lathe have? What is the invisible wear and tear? What is the overall degree of wear?
Answer:
(1) The first main parameter is 40, which means the rotation diameter of the workpiece is 400mm
The second main parameter is 1500, which means the length of the workpiece is 1500mm;
(2) The lathe is mainly composed of a spindle box, a feed box, a slide box, a tool rest, a tailstock, a light rod, a lead screw and a bed.
The spindle box is also called the bedside box. It houses the spindle and the spindle speed change mechanism. Its main task is to pass the rotational motion from the main motor through a series of speed change mechanisms so that the spindle can obtain the required forward and reverse motion. Different rotational speeds for the two types of steering. The feed box is also called the tool feed box. It is fixed on the left front side of the lathe. It is set up to adapt to different processing conditions and reasonably select the feed amount or specified pitch. The lead screw and light rod are installed on the front side of the lathe to connect the feed box and the sliding crate, and transmit the movement and power of the feed box to the sliding crate so that the sliding crate can achieve longitudinal linear motion. The slide box is actually the control box for the lathe's feed movement. It is equipped with a mechanism that converts the rotational motion of the lead screw and light rod into the linear motion of the tool holder. The longitudinal feed movement and transverse feed of the tool holder are realized through the light rod transmission. Movement and rapid movement, the turning tool on the tool holder is driven by the screw to move longitudinally in a straight line for turning threads. The tool holder is used to clamp turning tools and make them perform longitudinal, transverse or oblique feed movements. When processing slender workpieces, a tip is installed in the tailstock to support one end of the workpiece. If the tip is removed and a drill and other tools are installed, drilling, reaming and tapping on the lathe can be achieved. The lathe bed is installed on the left and right legs to support the three boxes (headstock, feed box, slide box), two bars (light rod, lead screw) and two frames (tool rest, tailstock) on the lathe.
Main motion: the workpiece rotates with the spindle.
Section 3 Drilling machine and boring machine
The common methods of hole processing are drilling with a drill, reaming with a reamer, reaming with a reamer and boring with a boring tool.
1. Drilling machine
1. Definition:
A drilling machine is mainly a machine tool that uses a drill bit to process holes on the workpiece. Usually, the rotation of the drill bit is the main movement. Axial movement is feed movement. Drilling, reaming, reaming, tapping, countersinking and countersinking bosses can be performed on the drilling machine.
Figure 4-14 The main work performed on the drilling machine
There are many types of drilling machines. According to different structures and uses, the commonly used ones include desktop drilling machines, vertical drilling machines and radial drilling machines.
Their most common feature is that the workpiece is fixed and the tool rotates and feeds along the spindle direction. The operation can be manual or motorized.
The processing accuracy of drilling can reach IT12, and the surface roughness Ra value can reach 12.5μm.
The main parameter of a drilling machine is the drilling diameter.
(1) Desktop drilling machine
Small drilling machine with drilling diameter ≤ 13mm.
The main shaft speed change is achieved by changing the position of the V-belt on the tower pulley.
(2) Vertical drilling machine
1. Composition:
It is composed of spindle, gearbox, column, workbench and base. The transmission of the spindle gearbox and the feed box is driven by the electric motor through the pulley, and the spindle is rotated through the spindle gearbox.
2. Movement characteristics:
The spindle rotates in the spindle sleeve, and at the same time, through the feed box, the spindle sleeve is driven to make linear motion, so that the spindle rotates on one side. One side follows the spindle sleeve and automatically performs axial feed according to the selected feed amount. The feed box and worktable can be adjusted up and down along the guide rails on the column to adapt to the processing of workpieces of different heights. The spindle of a vertical drilling machine cannot move in a plane perpendicular to its axis. To make the drill bit coincide with the center of the workpiece hole when drilling, the workpiece must be moved. Therefore, vertical drilling machines are only suitable for processing small and medium-sized workpieces.
(3) Radial arm drilling machine
1. Movement characteristics: The radial arm drill has a rocker arm that can rotate 360° around the column, and a main spindle box is installed on it. The main spindle box also Can move along the horizontal guide rail of the rocker arm. Therefore, the spindle can be adjusted to any position within the processing range of the machine tool. The workpiece is usually installed on the workbench for processing. If the workpiece is large, it can also be processed directly on the base. Depending on the height of the workpiece, the rocker arm can move up and down along the column to adjust the processing position.
2. Scope of application: Suitable for processing large and porous workpieces.
2. Boring machine
Motion description:
The boring tool is installed on the spindle or flat rotating disc; the workpiece is fixed on the workbench and can be processed along with the workbench. Longitudinal or lateral movement.
The rotation of the boring tool is the main motion, and the movement of the boring tool or the workpiece is the feed motion. Mainly used to process large holes, parallel holes, and concentric holes.
Scope of work:.
On the boring machine, you can not only bore holes, but also mill planes, grooves, drill, expand, ream, and turn end faces, outer circles, inner and outer annular grooves, and thread turning, etc.
Figure 4-18 The main work that can be performed on the horizontal boring machine
Category:
The boring machine is the main equipment for processing large box parts. According to the structure Depending on the purpose, boring machines can be divided into six types: deep hole boring machines, coordinate boring machines, vertical boring machines, horizontal boring machines, diamond boring machines and boring machines for automobile and tractor repair.
(1) Horizontal boring machine
1. Composition:
A common horizontal boring machine consists of a spindle and a flat rotating disc, a workbench, a spindle box, and a front column. , fuselage, rear column, tailstock and other parts.
2. Motion description:
During processing, the tool is mounted on the spindle or flat rotating disc, and various rotation speeds and feeds are obtained from the spindle box. The spindle box can move up and down along the guide rails on the column.
The workpiece is installed on the workbench and can move vertically or horizontally with the lower or upper slide together with the workbench. It can also rotate with the workbench around the circular guide rail under the workbench to the required position. Angle in order to process holes or planes at a certain angle. Since the boring machine has many moving parts, in order to ensure working reliability and processing accuracy, each moving part is equipped with a clamping mechanism.
3. Scope of work:
It mainly processes holes, especially many large holes, concentric holes and parallel holes on box parts.
4. Features:
The boring method can ensure the dimensional accuracy and positional accuracy of these holes. The boring accuracy can reach IT7, and the surface roughness Ra value is 1.6μm~0.8 μm.
5. Main parameter:
The main parameter of the horizontal boring machine is the spindle diameter.
(2) Coordinate boring machine
Coordinate boring machine is a type of high-precision machine tool.
1. Structural features:
1) Precision measuring devices with coordinate positions, such as precision rulers, grating rulers, laser interferometer positioning measurement devices, etc.;
2) The machine tool itself is manufactured with high precision;
3) It must be assembled and used under constant temperature conditions.
2. Scope of work:
The coordinate boring machine is mainly used for boring precision holes. In addition, it can also perform drilling, reaming, scraping, grooving, and fine milling. It can also be used as a measuring device to check the coordinate dimensions of workpieces processed by other machine tools.
3. Classification:
Coordinate boring machines are divided into single-column coordinate boring machines, double-column coordinate boring machines and horizontal coordinate boring machines according to different overall layouts.
The spindles of single-column coordinate boring machines and double-column coordinate boring machines are placed vertically, and the spindles of horizontal coordinate boring machines are placed horizontally.
1) The single-column coordinate boring machine consists of a bed, a column, a spindle box, a worktable and a sliding seat.
2) The double-column coordinate boring machine consists of a bed, a workbench, a beam, a spindle box, left and right columns and a top beam.
3) The horizontal coordinate boring machine consists of a bed, a workbench, a column, a spindle box, etc.
4. Features
(1) Good structural rigidity, capable of drilling and boring precision holes on solid workpieces;
(2) High spindle speed, The feeding amount is small;
(3) It is equipped with vertical and horizontal movable worktables, and their fine adjustment can reach 1μm. It also has a precise coordinate measurement system, so it is suitable for processing hole systems with small hole spacing errors.
(3) Diamond boring machine
1. Characteristics:
Processing is performed with a small feed amount and a high cutting speed. The dimensional accuracy is IT6, and the surface roughness Ra can reach 0.2μm.
2. Main parameters:
The main parameter of the horizontal diamond boring machine is the width of the work surface, and the main parameter of the vertical diamond boring machine is the diameter of the boring hole.