• 한국정밀공학회지
• /
• 제21권11호
• /
• pp.38-45
• /
• 2004

This paper discusses the minimum cutting thickness with a continuous chip in sub-micrometer order precision diamond cutting. An ultra precision cutting model is proposed, in which the tool edge radius and the friction coefficient are the principal factors determining the minimum cutting thickness. The experimental results verify the proposed model and provide various supporting evidence. In order to reduce the minimum cutting thickness a vibration cutting method is applied, and the effects are investigated through a series of experiments under the same conditions as conventional cutting method.

• 한국공작기계학회논문집
• /
• 제15권2호
• /
• pp.73-80
• /
• 2006

This paper describes a analysis on the chip thickness model required for cutting force simulation in ball-end milling. In milling, cutting forces are obtained by multiplying chip area to specific cutting forces in each cutting instance. Specific cutting forces are one of the important factors for cutting force predication and have unique value according to workpiece materials. Chip area in two dimensional cutting is simply calculated using depth of cut and feed, but not simply obtained in three dimensional cutting such as milling due to complex cutting mechanics. In ball-end milling, machining is almost performed in the ball part of the cutter and tool radius is varied along contact point of the cutter and workpiece. In result, the cutting speed and the effective helix angle are changed according to length from the tool tip. In this study, for chip thickness model analysis, tool and chip geometry are analyzed and then the definition of chip thickness and estimation method are described. The resulted of analysis are verified by compared with geometrical simulation and other research. The proposed chip thickness model is more precise.

• 한국정밀공학회지
• /
• 제22권1호
• /
• pp.32-38
• /
• 2005

Generally, cutting force models use a sin function method to calculate chip thickness. In slot end milling, the error from a sin function method is much bigger than other machining because a tool rotation angle in cutting is much larger. Thus in this paper, a new method to calculate chip thickness was suggested and evaluated. In a new method, tool position data according to tool rotation are checked and stored so that it is possible correct chip thickness is calculated. Cutting force waveforms simulated from a sin function method and a new method and measured waveforms from experiments were compared and error percentages were obtained. Finally, a new method had good results for simulating cutting force in slot end milling.

• 한국정밀공학회지
• /
• 제12권6호
• /
• pp.112-119
• /
• 1995

Early fracture and cutting force of ceramic tool for hardened STC3 steel was investigated in this study. It was found that early fracture of ceramic tool was mostly occurred before normal wear was progressed beyond a critical cutting speed and normal wear was performed under the critical cutting speed. The relationships among critical cutting speed, which was a cause of early fracture, suggested cutting cross section, that is, maximum thickness of cut and width of cut, and cutting force were examined. The following conclusions were obtained: (1)Critical cutting speed showed a high value in the case of small maximum thickness of cut and large nose radius, but was not influenced by width of cut, (2)Principal, feed and radial force, respectively, showed the proportional value to constant cutting area, width of cut and maximum thickness of cut orderly, (3)Occurrence of early fracture was dependent upon radial force.

• Design & Manufacturing
• /
• 제15권4호
• /
• pp.37-42
• /
• 2021

The tube necking process increases the thickness of the material, and some of the tube necking products require cutting on the inside of the formed product as a post-process. In order to prevent over-cutting or un-cutting due to increased thickness during cutting, it is necessary to know in advance the increase in thickness after forming. Therefore, in this study, the thickness change according to the tube necking was observed. Aluminum 3003-F and 6061-O were used for the materials used in the experiment, and necking was carried out up to 50% of the outer diameter of the tube through five processes. The two materials were formed under the same conditions, and the thickness of three points was observed in each process. In addition, the thickness increase of the two materials was compared, and the trend of thickness increase according to the cumulative necking ratio was observed. As a result of the experiment, both materials had the smallest thickness at the end of the formed product. In addition, as a result of comparing the thickness measurement values of the two materials, the maximum difference was 0.1mm, indicating that there was no difference in thickness between the two materials.

• 한국공작기계학회논문집
• /
• 제12권1호
• /
• pp.24-31
• /
• 2003

In the gas cutting of plate steel, the quality of the cut surfaces and sections is strongly dependent on the cutting conditions such as cutting speed, kerf width, plate thickness, material, distance between tip and specimen, and cutting oxygen pressure etc. The cutting tests of plate steel were carried out using CNC gas cutting machine. This paper deals with cut surface and section characteristics of plate steel in CNC gas cutting. Both top and bottom widths of kerf, the surface roughness(Ra, Rmax) of cutting surfaces are measured under various cutting conditions such as cutting speed, material, distance between tip and specimen, and cutting thickness. The photographs of cut surface and cut section are also analyzed under various cutting conditions.

• International Journal of Precision Engineering and Manufacturing
• /
• 제7권3호
• /
• pp.8-13
• /
• 2006

Plunge milling process is used for machining hole and is widely used in aerospace, automobile, and die/mold industries. The cutter is fed in the direction of spindle axis which has the highest structural rigidity. The kinematics of plunge milling differs from the traditional turning and milling in aspect of tool engagement and chip generation. This paper proposes the mechanistic cutting force model for plunge milling. Uncut chip thickness is calculated using the present cutter edge position and the previous cutter edge position. Instantaneous cutting force coefficients, which depend only on instantaneous uncut chip thickness, are derived based on the mechanistic approach. The developed cutting force model is verified through comparison of the predicted and the measured cutting forces.

• 한국정밀공학회지
• /
• 제23권3호
• /
• pp.39-46
• /
• 2006

In this work a dynamic cutting force model in ball end milling of inclined surface is introduced. To represent the complex cutting geometry in ball end milling of inclined surface, workpiece is modeled with Z-map method and cutting edges are divided into finite cutting edge elements. As tool rotates and vibrates, a finite cutting edge element makes two triangular sub-patches. Using the number of nodes in workpiece which are in the interior of sub-patches, instant average uncut chip thickness is derived. Instant dynamic cutting forces are computed with the chip thickness and cutting coefficients. The deformation of cutting tool induced by cutting farces is also computed. With iterative computation of these procedures, a dynamic cutting force model is generated. The model is verified with several experiments.

• 한국생산제조학회지
• /
• 제22권6호
• /
• pp.1003-1009
• /
• 2013

This paper presents a simple procedure to obtain the instantaneous cutting force constants needed to predict milling forces. Cutting force data measured in a series of slot milling tests were used to determine the cutting force constants at different feed rates. The values of the cutting force constants were determined directly at the tool rotation angle that maximized the uncut chip thickness. Then, the instantaneous cutting force constant was obtained as a function of the instantaneous uncut chip thickness. This approach can greatly enhance the accuracy of the mechanistic cutting force model for end milling. In addition, the influences of several cutting parameters on the cutting forces, such as the tool helix angle and axial depth of cut, were discussed.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.1522-1525
• /
• 2007

Circular milling operations are used to enlarge die and cylinder bores, and machine airframe pockets. In this case, cutting force varies as cutting tool position relative to workpiece. This paper presents a mechanistic model of geometric uncut chip thickness by predicting time varying cutter-part intersection as the cutter travels along the circular path. Compared with experimental results, the suggested cutting force model shows a good agreement.