First, the outer circle turning definition:

Outer turning is a machining process used to shape the outer surface of a workpiece into a cylindrical or conical shape. When turning, the workpiece is usually fixed on the spindle of the lathe, and the excess material on the workpiece is removed by the relative motion of the spindle rotation of the machine tool and the moving tool to achieve the desired shape and dimensional accuracy. Three conditions must be met when cutting:

1. There is relative movement between the tool and the workpiece.

2. The knife has an appropriate geometric Angle.

3. The tool material has certain cutting performance.

In order to obtain a surface that meets the requirements, the tool and the workpiece must interact and move relative to each other to remove excess material from the workpiece. During the cutting process, a layer of material on the surface of the workpiece is constantly cut by the tool to form a new surface, and there are three constantly changing surfaces on the workpiece, respectively:

1. Surface to be machined: the surface on the workpiece to be cut.

2. Machined surface: the surface formed on the workpiece after cutting by the tool.

3. Transition surface: The part of the surface on the workpiece formed by the cutting edge of the tool, which is cut in the next stroke, the next turn of the tool or the workpiece, or by the next cutting edge.

 

 

Cylindrical turning is usually used to manufacture shaft parts, bearing seats, gears, flanges and other mechanical parts. It is a common metal processing process, which can achieve different processing effects by controlling parameters such as the position, speed and feed rate of the tool.

In the outer circle turning, it is necessary to select the appropriate tool and processing parameters, and make appropriate adjustments according to the material and shape of the workpiece to ensure the processing quality and efficiency.

 

Second, which types of round turning are divided into:

1. Classified according to the tool movement mode: divided into longitudinal turning and transverse turning two kinds. Longitudinal turning means that the tool is turned along the axial direction of the workpiece, which is suitable for processing long axis parts; Transverse turning means that the tool is turned along the radial direction of the workpiece, which is suitable for processing short axis parts.

2. According to the processing accuracy classification: divided into rough car, semi-fine car and fine car three kinds. Rough lathe refers to the preliminary processing of the workpiece, remove the excess material, leaving a certain processing margin; Semi-finishing refers to the further processing of the workpiece after rough machining, reducing the processing allowance and improving the surface quality; Finishing refers to the final finishing of the workpiece after processing, so that it can achieve the accuracy and surface quality required by the design.

3. Classification according to the shape of the tool: It is divided into three kinds of straight turning tool, elbow turning tool and forming turning tool. Straight head turning tool is suitable for machining outer circle, inner hole and end face, etc. Elbow turning tool is suitable for machining curved surface and chamfer, etc. The forming tool is suitable for machining special shaped parts.

4. According to the processing method classification: divided into manual turning and CNC turning two kinds. Manual turning refers to the turning process by manual operation lathe, which is suitable for small batch production and parts with low processing accuracy requirements; CNC turning refers to automatic turning by CNC system control lathe, which is suitable for mass production and machining parts with high precision requirements.

The above are several common classification methods of outer circle turning, and different classification methods are suitable for different processing needs.

 

 

Third, the form of outer circle turning:

1. Ordinary turning: The use of traditional lathes and tools for turning, suitable for processing various materials of the outer round surface.

2. CNC turning: The use of CNC lathes and tools for turning, can achieve high precision, high efficiency processing, suitable for mass production.

3. Strong turning: Turning with high-power lathes and tools can process large and heavy workpieces.

4. High-speed turning: The use of high-speed lathes and tools for turning, can improve processing efficiency and surface quality, suitable for processing high hardness materials.

5. Precision turning: The use of precision lathes and tools for turning, can achieve high-precision processing, suitable for processing precision parts.

 

Fourth, the way of turning the outer circle:

1. Longitudinal turning: The tool is turned along the axial direction of the workpiece, which is suitable for processing long axis parts.

2. Transverse turning: The tool is turned along the radial direction of the workpiece, which is suitable for processing short axis parts.

3. Hybrid turning: The tool is turned along the axial and radial direction of the workpiece at the same time, which is suitable for processing complex shaped parts.

4. Contour turning: Contour turning is a kind of turning technology, which means that the tool needs to carry out axial and radial feed action at the same time when turning conical or contour surfaces. This turning method is suitable for small batch and batch production of workpiece with more complex shape, and the productivity is 10 to 15 times higher than that of ordinary lathes.

In the copying turning, it is necessary to pay attention to the difference in the size and direction of the cutting force of each feed, and the elastic deformation of the tool bar will also be different, which will lead to the deviation of the diameter size, and the corresponding compensation must be made.

 

Fifth, the application of external turning coolant has the following aspects

1. Cooling effect: During the turning process, the friction between the tool and the workpiece will produce a lot of heat, if not cooled in time, it will lead to increased tool wear, workpiece deformation, surface quality decline and other problems. The coolant can take away the heat between the tool and the workpiece, reducing the temperature, thereby extending the tool life and improving the processing quality.

2. Lubrication: The coolant can form a lubricating film between the tool and the workpiece, reducing the coefficient of friction, reducing tool wear, and improving processing efficiency.

3. Cleaning effect: During the turning process, a large number of chips and metal powder will be produced, which, if not cleaned in time, will block the tool and coolant channel, affecting the processing quality and tool life. The coolant washes away chips and metal powders, keeping the tool and coolant channels clean.

4. Anti-rust effect: the coolant usually contains anti-rust agents, which can prevent the workpiece from rusting during processing.

5. Environmental protection: The coolant can be recycled to reduce waste liquid discharge and reduce environmental pollution.

When selecting the outer circle turning coolant, it is necessary to consider the processing material, tool material, processing parameters and other factors to choose the appropriate coolant type and concentration. At the same time, the coolant needs to be replaced regularly to keep it clean and effective.

 

Sixth, the selection of external turning tools need to consider the following factors:

1. Processing materials: Different materials need to choose different tool materials and geometric shapes. For example, high-speed steel or cemented carbide tools are usually selected when processing steel parts, while PCD tools are usually selected when processing aluminum alloys.

2. Machining accuracy: Roughing usually requires the tool to have a larger cutting depth and feed, so it is necessary to choose the tool material and geometry can withstand the larger cutting force and wear of the tool.

3. Tool shape: The shape of the external turning tool is usually W peach shape, T triangle shape blade, according to the working condition requirements to choose the appropriate main declination Angle and cutting edge Angle.

4. Tool coating: Tool coating can improve the wear resistance and corrosion resistance of the tool, thereby improving the processing efficiency and processing quality. Commonly used tool coatings include TiN, TiCN, TiAlN, etc.

 

Seventh丶The following factors need to be considered in the selection of the tip arc of the external turning tool:

Among them, the most common blade tip arc radius is 0.1㎜, 0.2㎜, 0.4㎜, 0.8㎜, 1.2㎜ and so on. When selecting the radius of the tool tip arc, the following aspects can be referred to:

1. Avoid processing interference: the radius of the tool tip should not be greater than the minimum radius of the concave profile of the part.

2. Consider the tool strength: the radius of the tool tip should not be too small when roughing, otherwise it will be easy to damage the turning tool because the strength of the tool head is too weak or the heat dissipation capacity of the tool body is poor.

3, adapt to the feed: the radius of the tool tip should be commensurate with the maximum feed, should be greater than or equal to 1.25 times the maximum feed, but to avoid the tool when cutting chatter, in general, the radius of the tool tip in 0.8mm below is not easy to lead to processing chatter.

4. Influence roughness: the radius and feed of the tool tip are geometrically related to the residual height of the machined surface, and the residual height is related to the radius and feed of the tool tip.

In actual machining, the appropriate tool arc can be selected according to the needs of various factors. Finishing with 0.1-0.2mm arc tip, high precision and roughness requirements. Semi-finishing selection of 0.2-0.4mm arc, general fine coarse mixed processing. And rough cutting depth is not large, finishing roughness requirements are not high. Roughing uses 0.8-1.2mm arc tip, which can reasonably increase the cutting depth and quickly peel off the excess parts of the workpiece.

 

 

In short, the selection of external turning tools needs to comprehensively consider the processing materials, processing accuracy, tool shape, tool cutting edge belt, tool chip discharge groove, tool coating and other factors, and according to the specific working conditions and processing parameters to choose.