Swiss type automatic lathe machine: Introduction
Swiss type automatic lathe is a type of single spindle automatic lathe machine. The Swiss type automatic lathe machine is used for machining small and slender parts. This lathe is called by many names such as Swiss type automatic lathe, Sliding head automatic lathe, and moving headstock lathe machine. The headstock moves in the axial direction and so it is named as sliding head or moving headstock lathe machine.
Most probably this type of lathe machine is used for mass production, manufacturing slender and tubular objects etc. Even small diameter parts can be machined by this lathe. It can machine those parts at an accuracy of 0.005 mm to 0.0120 mm. Both conventional automatic lathe and Swiss type automatic lathe are not the same, they are different from each other in many aspects.
Parts of Swiss type automatic lathe machine
- Sliding headstock
- Tool bracket
- Feed base
The sliding headstock is the main part of this lathe machine which slides along the guideways on the bed. Due to the sliding motion, the headstock is named a sliding headstock. The bar stock or work is held by the collet Chuck in the sliding headstock. There is a bell cam in the sliding headstock and it is connected to the camshaft for the axial motion.
Tool bracket is a tool holding attachment that is mounted on the bed in between the sliding headstock and the feed base. It is placed nearly close to the headstock. This tool bracket consists of five cutting tool slides. Among five tools slides, two are horizontally placed (in front and rear position) and the remaining tools slides are placed above the horizontal tools slide in a radial manner. There is a bush in the tool bracket for supporting and guiding the bar stock or work spindle to be machined. All told slides are designed and placed to be move back and forth.
The feed base of Swiss type lathe is mounted on the right side just next to the tool bracket and they can move along the bed. Their movement can be controlled by the plate cam which is fitted on the camshaft. The feed base attachment is used for performing multiple operations such as drilling, boring, and thread cutting.
In Swiss type automatic lathe, the camshaft is mounted at the front of the machine to control the movement of the lathe parts. This shaft consists of three cams and they are fitted at three different places in the shaft. The bell cam camp is fitted at the right end of the shaft to control the movement of the sliding headstock. Plate cams are fitted in the middle and right end of the camshaft to control the movement of the tool bracket and feed base.
Working principle of swiss type automatic lathe machine
The rotating collet in sliding headstock holds the bar stock. In headstock, the sliding movement is initiated by the belt cam which is attached to the camshaft. Hence the longitudinal feed is obtained. There is a hard round brush in the tool head or bracket which helps in guiding the bar stock. The tool bracket consists of five single point cutting tools to perform multiple operations.
In the tool bracket, the bar stock is made to pass radial through the cutting tools. After headstock sliding and longitudinal feed is given, all tools in the tool head start removing the material from bar stock. These tools can be able to undergo multiple operations at the same time.
Cutting operations like turning and farming are mostly done by the tools in a horizontal setup. The tools in the vertical setup can able to do other operations such as undercutting, chamfering, knurling and cutting off. The headstock comes back to its original position after finishing the machining process.
The above line diagram is about a typical transmission in Swiss type automatic lathe machine. This lathe machine is equipped with two motors called the main motor and an independent drive. The main motor is directly connected with the back shaft and it drives it at high speed.
Rotational motion of the back shaft is transmitted to the main camshaft using a lot of power transmission elements such as a worm, worm wheel, change gears, belt drives etc. The main camshaft and various cams such as bell cam or disc cam, tool cam, and end tool cam control the entire machine movements.
Particularly the movement of the headstock and tool slides are controlled using this main motor. The independent motor drive controls the movement of the end attachments called feed base and end tools. There are three spindles available to carry end tools in the feed base and all the spindles can be either at rest or in movement.
The feed base can be moved in sideways according to the position of the cam mounted in the camshaft. In Swiss type automatic lathe machine one complete revolution of the camshaft is considered as cycle time and it produces one compound at one revolution of the camshaft.
Some operating guidelines for swiss type automatic lathe machine
- While performing turning operation at a distant from the guide Bush in tool bracket only low feed must be used.
- To get an accurate and smooth surface can narrow parting off tool is preferred than a wider one and it can also be used as a bar stop.
- During stop turning operation there must be a dwell between larger and smaller diameter. The dwells must be avoided during taper turning.
- To get a proper and correct taper small dwell must be always allowed while positioning the tool from neutral. Wide and long tapers always result in low accuracy.
- To make sure the guide bush support for bar stock, drilling operation must be done in the beginning and centering operation must be done before drilling deep holes in the bar stock.
Characteristics and significance of swiss type automatic lathe machine
- It has a sliding headstock which provides axial feed and has a bar stock in it.
- There are special attachment end tools called feed base has some additional end cutting tools to perform operations like drilling boring and thread cutting.
- There are five cutting tools placed radially to the bar stock in the tool head or tool bracket along with guide bush support.
- The main camshaft of the machine controls the movement of the headstock, tool slides and end attachment tools with the help of motor and power transmission elements.
- Unlike normal let machine tailstock is absent and it is replaced by feed base along with end tools.
Advantages of swiss type automatic lathe machine
- It has a rigid and solid construction like other lathe machines.
- High precision and accuracy can be easily achieved.
- The tool bracket consists of five tools that help in performing multiple operations simultaneously.
- The moment of the machine parts can be easily controlled by interchanging the cam in the camshaft.
- As the machine is driven by the motors, a wide range of speed is available.
- Additional attachments like micrometre are also possible in Swiss type lathe machine.
Disadvantages of swiss type automatic lathe machine
- The machining cycle time is more.
- By default, it does not support multi spindles but multi spindles end attachment tools are there.
- In productivity-wise, conventional automatic lathe machines are superior for small.
Applications of swiss type automatic lathe machine
- Used for mass production of small tubular and slender parts.
- Mainly used for manufacturing wristwatch parts, mini shafts, medical devices etc.
- Used for manufacturing complex parts with high precision and accuracy.