Vertical Lathes Research Articles

Research Status of Hydrostatic Bearing Technology in Machine Tool

Background: As the basis of mechanical manufacturing, large-scale machine tools are being developed for improving processing accuracy, load-bearing capacity and rigidity. Hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram are important components of large machine tools; with the continuous improvement of product accuracy requirements, the research on the hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram has become more important. Objective: This paper presents the current research on hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram to highlight the importance of hydrostatic ram in improving the machining accuracy of machine tools. The study aims to lay a foundation for research and development of hydrostatic ram in the future. Methods: Firstly, the hydrostatic bearing technology is introduced. Secondly, the research status of hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram is presented to provide theoretical basis for improving the processing performance of rest ram. Result: Deformation compensation and thermal deformation compensation of hydrostatic ram have been studied more. Most of the research study focuses on the accuracy of hydrostatic ram, but less on the bearing performance of hydrostatic ram. Conclusion: Breakthroughs have been made in the research on precision control and structural form of the hydrostatic bearing at home and abroad. Most scholars take the ram of Computer Numerically Control (CNC) boring and milling machines as the research object, but there is less research on the ram of vertical lathes. Therefore, the academic circle should pay more attention to the bearing performance of the hydrostatic ram of vertical lathes.

Damping in ram based vertical lathes and portal machines

Chatter vibrations originated by the machine structure are a major limitation for the productivity of ram based machines performing heavy duty operations. Consequently, the damping of the machine structure has a capital importance. It is known that interfaces and guideways are the main origin of damping. Recently, the use of active dampers has been introduced in industry. In this work, the damping of hydrostatic and rolling guideways with and without active damping has been experimentally identified and compared using receptance coupling. The results show that hydrostatic guidance can introduce 3–4 times more damping than a roller based system. However, the introduction of active damping is a game changer enhancing damping more than 30 times.

Design of Two-Axial Actuator for Controlled Vibration Damper for Large Rams

Machine tool rams are important constructional elements found on vertical lathes as well as on many other machines. In most cases, a machine tool ram constitutes an assembly with significant dynamic compliance that affects the machine’s ability to achieve stable cutting conditions. There are various solutions for increasing a machine tool ram’s stiffness and damping. This paper describes an innovative concept of a two-axial electromagnetic actuator for controlled vibration dampers with high dynamic force values. The described solution is purposefully based on the use of standard electric drives. As a result, the size of the actuator is easier to scale to the required application. The solution is designed as a spacer between the end of the ram and the head. The paper presents the actuator concept, construction design, current control loop solution and experimental verification of the controlled vibration damper’s function on the test ram in detail. The presented position measurement concept will enable the use of non-contact position sensors for motor commutation as well as for possible use in vibration suppression control. Applications can be expected mainly in the field of vibration suppression of vertical rams of large machine tools.

THE VERTICAL ARRANGEMENT OF LATHE MACHINING CENTERS: THE TREND OF MACHINE TOOLS OR JUST A VARIETY OF MACHINES?

The article analyzes vertical lathes from a retrospective point of view, defines the stages of formation and development of such machines. The advantages of vertical lathes are analyzed, and an attempt is made to find out the prospects for the development of such machines. The purpose of this work is to clarify the scope of rational use of vertical lathes. The results of calculations proving the advantages of such machines in terms of saving production space in comparison with the horizontal layout are presented.

Prediction model of the clearance oil film for static vertical rail considering the ram deformation

In order to improve the cutting rigidity of hydrostatic oil pad on large vertical lathes’ vertical rail of hydrostatic ram, on the basis of a single-chamber oil pad, this paper proposed a new type of the double-chamber oil pad. Pressure field distribution law of the single-chamber and the double-chamber oil pad was obtained by the finite element volume method. Then, using the fluid–structure coupling method and Workbench software the deformation law of ram was obtained under different working conditions. Finally, oil film’s prediction model of the single-chamber and the double-chamber oil pad was solved under different working conditions. Oil film’s prediction model of the single-chamber oil pad and the double-chamber oil pad was obtained under various working conditions. The results show that the maximum deformation of the single-chamber of upper oil pad ranges from 0.079 to 0.92 µm, while the double-chamber oil pad ranges from 0.07 to 0.68 µm. The maximum deformation of the single chamber of lower oil pad ranges from 0.91 to 9.21 µm, while the double-chamber oil pad ranges from 0.74 to 9.14 µm, and the maximum deformation of the double-chamber oil pad is less than that of the single chamber, which shows that the rigidity of the double-chamber oil pad is better than that of the single chamber. The results are helpful to improve the bearing performance and service life of bearings.

Using Hydro-Pneumatic Accumulators to Increase the Operation Safety of Heavy Duty Vertical Lathes

This paper presents the principle diagrams that can be used to manufacture hydraulic systems that can prevent the seizing of the circular hydrostatic guideways of the table in the case of heavy-duty vertical lathes, with over 4000 mm diameter. The proposed systems will provide the lubrication of the guideways of the table as long as this one rotates up to a possible stop caused by an accident. Lubrication is achieved even in the absence of the machine supply voltage because it is provided by systems that do not need electrical power to operate. The absence of hydrostatic pressure, even in only one of the hydrostatic pockets, caused by the breaking of a hose, can be detected and will trigger the safety system activation.

Characteristic Analysis on Heavy Hydrostatic Bearing of DVT500 Vertical Lathe

With increasing demands for product quality, and the performance of assembly equipment plays a decisive role for product quality, national experts and scholars conduct in-depth research on the performance of the assembly equipment. In this paper, a research simulation on hydrostatic bearing performance of heavy-duty vertical lathes DVT(digital vertical tool) 500 is carried out by using finite element software FLUENT to simulate the fluid pressure field and temperature field distribution of sector oil recess at different work platform rotational speed. The law of these field distributions is also obtained. The results show that: the rotational speed of the work platform has a greater impact on pressure field and temperature field of gap fluid flow. Numerical results can reflect the true hydrostatic bearing fluid movement, the actual simulation results provide a theoretical basis for optimization design of the Engineering hydrostatic bearing oil cavity.

The Optimization Design of the Rotary Worktable for Vertical Lathe Based on Structural Bionic Method

Based on the structural bionic method, the rotary worktable of vertical lathe was optimized. Through fuzzy similarity analysis, the similarity of the bionic prototype and the rotary worktable was obtained, and the rationality of the bionic prototype was verified. According to the bionic prototype, the optimization model was established. Then it was transferred into the Workbench of the ANSYS to be analysed by the finite elements method. Comparing with the prototype, the results indicate that the bionic worktable’s mass reduces 280kg, and the deformation reduced 4.7%. The first five natural frequencies of bionic worktable increased. The results show that the bionic rotary worktable is more reasonable. It offers a new solution to optimize the rotary worktable of various vertical lathes.

ON THE DEBOSSING, ANNEALING AND MOUNTING OF BELLS

Changes in the frequencies of the musical partials of various types of bells following debossing dismounting/mounting and annealing/quench annealing are reported. Debossing, dismounting and quench annealing lead to frequency drops, while mounting gives rises. Annealing can lead to frequency increases or decreases depending upon the maximum temperature employed and the initial residual stress. Qualitative explanations of these phenomena are given in terms of changes in crown stiffness, internal stress and alloy phase structure. These are supported by the results of X-ray diffraction measurements. Although the effects are all small they can be large enough to be detected by a reasonably musical car. This, together with the fact that the effects cannot be controlled, gives a plausible explanation of why modern bellfounders use vertical lathes for tuning, even with small carillon bells, and do not anneal bells when trying to control warble.

Application of IGP-4 in hydrostatic guides and gearboxes of vertical lathes

Application of IGP-4 in hydrostatic guides and gearboxes of vertical lathes

Testing the roundness of large details

1. Instrument ARF-1M is suitable for recording roundness irregularities of details in the course of their machining on lathes, since it eliminates the effect of the floating face plate. 2. An analysis of the instrument's errors has shown that potentiometers with a lever and gear transmission can be used as transducers. 3. The precision of measurements provided by this instrument makes it possible to recommend it for testing large details during their machining on vertical lathes, and for testing the beating of face plates of repaired lathes.