In the turning of carbon steel and other plasticity metal materials, if not take chip removal measures, it is easy to form strip-like chips, continuous winding on the workpiece, tool and tool carrier, this chip can scratch the alresdy machined surface and the lathe bed and influences the machining, winding on the operating handle will effect operate, even hurt people, so we should take effective measures to avoid the emergence of strip chip, and make the chip be granulared or curled into a chip of a certain length.
In turning, in order to achieve the chip is not a strip shape, you can change the tool geometry angle, adjust the amount of cutting, change the chip groove shape, installation of chip block or installation of chip breaking device and so on.
1. Change the geometric angle of the turning tool. In the case of the depth of cut and feed have been selected, changing tool geometric angle will make the chip breaking off. Such as increasing the main declination will increase the thickness of the cutting, so as to achieve the purpose of chip breaking. But the method of changing the angle of tool angle to control chip shape often destroys the most appropriate geometric angle of turning tool. The most common method is to grind a double edge angle on the cutting edge, such as reducing the rake angle at the tool point, increasing the tip strength so that the chip curls away from the workpiece. But when cutting high strength and high toughness materials, it is difficult to chip.
2. Change the shape of chip breaker. Through grinding different chip breaker on the cutter head, the purpose of cutting control is achieved. The shape of chip breaker should be observed on the orthogonal plane. The usual chip breaking groove has three kinds: straight line, arc shape, straight line shape and arc shape. Use the straight line chip breaking groove, the chip rolls toward the machined parts. The chip breaker is an arc turning tool with a positive rake angle and is generally suitable for turning low carbon steel and medium carbon steel. Because of its large rake angle, the, the grinded negative chamfer angle gradually widened from the tip of the tool to the end, that is, good chip breaking condition can be obtained, and the cutting edge strength can be ensured.
When chip breaking is used, the width of the chip groove and the radius of the bottom of the groove should not too large, thus the smaller the chip curling radius, the easier it is to break, but if too small, it cannot achieve an ideal cutting effect.
3. Install chip breaker platform. Chip breaker platform is a plate with a certain thickness, the thickness of which is generally controlled by 1/3 to 1/4 of the height of the tool bar. This method is suitable for the case of medium cutting depth and the feed rate is not large.
4. Install chip breaker plate or chip breaker. It is to install the chip breaker at certain distance behind the tool to assist the chip breaking. The chip breaker plate takes the front of the turning tool as the center, the length of the upper and the lower is about 5mm, the middle concave and the periphery are high, and equipped with milled concave surface of the right cross helical tooth.
When used, the chip breaker plate is fixed on the tool post, so that it is compatible with the distance between the turning tool, after adjustment, tightened the nut which on the tool post. When the chip is rolled out from the rake face to the concave of the chip breaker plate, they encounter obstacles, friction to make it automatically broken. Depending on the difference of cutting conditions and the chip material, chip breaker with a beveled web or concave suface can be used respectively. When the cutting amount is large or the cutting material is softer, adopt the chip breaker with concave surface and beveled web. When the cutting material is hard and the cutting amount is not too large, the concave surface chip breaker is adopted.
5. Adjust the amount of cutting. In actual operation, change the amount of cutting is the most simple method to chip breaking, usually wear a chip flute and rake angle on the tip of the turning tool, if the machining allowance and lathe rigid enough, can use the method of increase the feed rate and reduce the cutting speed to achieve the purpose of chip breaking.