System Error Concept Of Thermal Deformation Control Measures Of Cutting Machine

- Nov 17, 2020-

(1) Reduce heat generation and heat insulation. In order to reduce the heat generated by the machine tool in the process system, all heat sources that may be separated from the host. Such as the motor, gearbox, screw pair, fuel tank, etc., should be placed outside the machine tool as much as possible. For parts and components that can separate heat sources, such as main shaft bearings, screw pairs, wheel pairs, friction clutches, etc., the friction characteristics should be improved from the structure and lubrication to reduce heat generation.

Cutting machine is an important part of reducing thermal deformation. For this reason, static pressure bearings, low temperature dynamic pressure bearings and air bearings are usually used in the manufacture of machine tools, and low bulge lubricating oil is used. These are all conducive to controlling the increase in bearing temperature. *If the heat source cannot be separated from the machine tool, it can be Install heat insulation materials on the joint surfaces of these heating parts and large machine tools (when the heat source is not good at heat dissipation, heat dissipation measures should be adopted) to prevent heat conduction.

(2) The heat of the cutting machine controls the temperature rise and thermal deformation of the machine tool. Such as CNC machine tools and processing towel cores, etc., generally use refrigerators to

The forced cooling of the lubricating oil greatly reduces the heating and deformation of the headstock components.

(3) Speed up the temperature rise and maintain thermal balance. According to the law of internal thermal deformation, after the cutting machine reaches thermal equilibrium during the preheating stage of the machine tool, the thermal deformation gradually tends to be constant, and the machining accuracy can be guaranteed after that. Out of this, shorten the warm-up period of the machine tool, which is beneficial to improve productivity and ensure processing accuracy.

Various single-factor processing errors can be divided into systematic errors and accidental errors according to their nature.

1. Cutting machine system error

When the hydraulic cutting machine processes a batch of parts in sequence, the error that the size does not change is a regular change is called system error monitoring. The former is a constant system error, and the latter is a systematic error that changes regularly (variable recovery system error). For example, use a diameter smaller than the specified size o. 02 reamer, the diameter of all holes reamed is smaller than the specified size o. 02, this kind of error is often a systematic error. In the case of an axle, due to the wear of the turning tool, the white diameter of the turning shaft is larger than one. The increase in the vertical diameter of the shaft is regular, so the error caused by the tool wear belongs to the systematic error of regular change (variation). Bai system error). The thermal deformation of Ran Ruding's system is also a variable system error.

 2. The cutting machine is occasionally poor

In adding a batch of parts, the size and direction of this kind of error are irregularly changed, sometimes large, sometimes small, sometimes positive, sometimes negative. Such errors are called accidental errors. For example, when a four-column cutting machine uses a reamer to process a batch of holes, under the same conditions, a batch of holes with exactly the same diameter and size is still required. This may be due to uneven hardness of the blank and AJJl' margin. Differences, internal stress redistribution causes deformation and other factors, these factors are always changing. Although the causes of accidental errors are various, and the role of cutting machines is very complicated, the law of accidental errors can be found and controlled by the method of mathematical statistics.