This Application is a Section 371 National Stage Application of International Application No. PCT/KR2011/006521, filed Sep. 2, 2011 and published, not in English, as WO2012/033309 on Mar. 15, 2012.
The present disclosure relates to a machine tool bed, and more particularly, to a bed rib structure of a turning center.
A machine tool, particularly, a bed of a turning center is manufactured by a casting forming method, and as illustrated in
In a case of a general machining center, because the machining center has a symmetric structure, a control for thermal displacement of the structure according to a change in external temperature may be compensated in real time, but as illustrated in
As illustrated in
Because the shape of the bed 10 of the turning center of the related art is designed considering only the static stiffness in the condition of the maximum cutting force without considering an influence of the change in external temperature, as illustrated in
However, in the bed structure of the turning center of the related art, a relative thermal displacement amount at end points of the work piece and the tool shows a considerably high value (for example, 20 to 30 μm) in accordance with a test condition, and a higher thermal deformation amount is shown in a high speed and high precision processing condition.
One of methods for reducing a temperature gradient of a machine tool bed and the thermal displacement due to the temperature gradient is a method of improving a material of the machine tool bed such as a method of using a casting material having an excellent thermal characteristic. However, there is a problem in that the above method causes a heavy burden in terms of cost, and the thermal displacement due to occurrence of a local temperature gradient according to a change in thermal environment may not be basically and greatly reduced by only the above countermeasure.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
This summary and the abstract are provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. The summary and the abstract are not intended to identify key features or essential features of the claimed subject matter, nor are they intended to be used as an aid in determining the scope of the claimed subject matter.
The present disclosure has been made in an effort to solve the above problem in the related art, and one aspect of the present disclosure is to provide a shape of a bed of a turning center capable of improving processing accuracy by allowing a temperature response speed at each portion of the bed of the turning center to be uniform, thereby reducing thermal displacement due to occurrence of a local temperature gradient.
The present disclosure has been made to suggest a shape of a rib of a bed, in which thermal deformation of a turning center due to a change in external temperature may be reduced, and relative displacement at end points of a tool and a work piece may be reduced by securing static stiffness in a condition of maximum cutting force, by utilizing a topology optimization method, and improve processing quality.
Specifically, the present disclosure provides a bed 10 A bed 10 for use with a turning center assembled with a main shaft housing 20 in which a work piece is chucked, a turret 40 and a tool table 50 configured to process the work piece by a tool, and a transfer apparatus 30 configured to transfer the turret 40 and the tool table 50, the bed 10 comprising: a rib 13 including a plurality of rib elements 13-1, 13-2, 13-3, and 13-4.
Further, the rib element comprises a first rib element 13-1 positioned at a lower portion of the bed 10 where the main shaft housing 20 is assembled, and a second rib element 13-2 positioned at a lower portion of the bed 10 where the transfer apparatus 30 is assembled, and an interval α of the first rib element 13-1 is smaller than an interval β of the second rib element 13-2.
According to a result of optimization by a topology optimization method, the interval α of the first rib element 13-1 and the interval β of the second rib element 13-2 is 0.5<α<0.6 and 1.37<β<1.55, and static stiffness in a radial direction (x-axis) of the work piece is maximized (25% improvement), and thermal deformation is also minimized (10% reduction).
Meanwhile, the rib elements 13-1, 13-2, 13-3, and 13-4, which constitute the bed 10, may be manufactured to have a left and right symmetric shape.
That is, the rib element further includes a third rib element 13-3 and a fourth rib element 13-4, which are disposed adjacent to the second rib element 13-2, an interval of the third rib element 13-3 is identical to the interval β of the second rib element 13-2, and an interval of the fourth rib element 13-4 is identical to the interval α of the first rib element 13-1, and thereby the rib element may have a left and right symmetric shape, as a whole.
In addition, the rib 13 may be an integrated single structure.
According to the present disclosure, by adjusting, by the topology optimization method, the interval α of the first rib element 13-1 positioned at a lower portion of the bed 10 where the main shaft housing 20 is assembled and the interval β of the second rib element 13-2 positioned at a lower portion of the bed 10 where the transfer apparatus 30 is assembled, among the rib elements, so as to improve a temperature response speed at a portion where thermal resistance is high, occurrence of a local temperature gradient may be prevented by allowing a temperature response speed at each portion of the bed to be uniform as a whole, and accordingly, processing accuracy by reducing thermal displacement.
Particularly, in a case in which the relative ratio between the interval α of the first rib element 13-1 and the interval β of the second rib element 13-2 is 0.5<α<0.6 and 1.37<β<1.55, the static stiffness in a radial direction (x-axis) of the work piece is maximized (25% improvement), and the thermal deformation is also minimized (10% reduction).
10: Bed
11: Upper bed
12: Lower bed
11-1 to 11-4 (12-1 to 12-4): Rib element
13: Rib
13-1 to 13-4: First to fourth rib elements
20: Main shaft housing
30: Transfer system (transfer apparatus)
40: Turret
50: Tool table
α: Interval of first rib element
β: Interval of second rib element
Hereinafter, an exemplary embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.
According to the present disclosure, in order to reduce thermal deformation in a turning center according to a change in external temperature and improve static stiffness for a high speed and high precision processing in a condition of maximum cutting force, an optimum bed rip shape, which secures sufficient stiffness in a direction in which maximum cutting force is applied and minimizes relative thermal displacement at end points of a tool and a work piece according to a change in external environmental temperature, is derived by topology optimization.
As illustrated in
As illustrated, relative intervals of a first rib element 13-1, a second rib element 13-2, a third rib element 13-3, and a fourth rib element 13-4, which constitute a rib 13 in a bed 10, are optimally designed through the process of the topology optimization.
As illustrated in
In addition, as illustrated in
In this case, as illustrated in
Further, it may be confirmed that in a case in which the rib 13 is designed in a left and right symmetric shape, as a whole, maximum thermal deformation with respect to a change in external temperature is reduced, and maximum bed static stiffness at a condition of maximum cutting force is secured, by setting an interval of the third rib element 13-3 adjacent to the second rib element 13-2 to be identical to the interval β of the second rib element 13-2 and setting an interval of the fourth rib element 13-4 adjacent to the third rib element 13-3 to be identical to the interval α of the first rib element 13-1.
The following Table 1 shows comparison between effects of the related art and the present disclosure, and it may be confirmed that in the present disclosure, the static stiffness in an x-axis direction (radial direction of the work piece) is improved by 25%, and the thermal deformation is reduced by 10%, compared to the related art.
As illustrated, in the present disclosure, the thermal deformation in the x-axis direction (radial direction of the work piece) is reduced by 10%, compared to the related art.
While the specific embodiment of the present disclosure has been described above, the spirit and scope of the present disclosure is not limited to the specific embodiment, and a person with ordinary skill in the art to which the present disclosure pertains will appreciate that various modifications and alterations are possible, without departing from the subject matter of the disclosure
Therefore, the embodiments disclosed above are set forth to provide a complete understanding of the scope of the disclosure to a person with ordinary skill in the art to which the present disclosure pertains and thus are illustrative and is not intended to be in any way limiting, and the present disclosure will only be defined by the scope of the claims.
According to the present disclosure, by adjusting, by the topology optimization method, a relative ratio between the interval α of the first rib element 13-1 positioned at a lower portion of the bed 10 where the main shaft housing 20 is assembled and the interval β of the second rib element 13-2 positioned at a lower portion of the bed 10 where the transfer apparatus 30 is assembled, among the rib elements, so as to improve a temperature response speed at a portion where thermal resistance is high, occurrence of a local temperature gradient may be prevented by allowing a temperature response speed at each portion of the bed to be uniform as a whole, and accordingly, processing accuracy may be improved by reducing thermal displacement.
Particularly, in a case in which the relative ratio between the interval α of the first rib element 13-1 and the interval β of the second rib element 13-2 is 0.5<α<0.6 and 1.37<β<1.55, the static stiffness in a radial direction (x-axis) of the work piece is maximized (25% improvement), and the thermal deformation is also minimized (10% reduction).
Although the present disclosure has been described with reference to exemplary and preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the disclosure.
Number | Date | Country | Kind |
---|---|---|---|
10-2010-0086815 | Sep 2010 | KR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/KR2011/006521 | 9/2/2011 | WO | 00 | 3/6/2013 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2012/033309 | 3/15/2012 | WO | A |
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Entry |
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Search Report dated Apr. 4, 2012 and written in Korean for International Application No. PCT/KR2011/006521 filed Sep. 2, 2011, 3 pages. |
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Number | Date | Country | |
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20130160619 A1 | Jun 2013 | US |