JP6746840B2 - Method for correcting thermal displacement of turret - Google Patents
Method for correcting thermal displacement of turret Download PDFInfo
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- JP6746840B2 JP6746840B2 JP2016105061A JP2016105061A JP6746840B2 JP 6746840 B2 JP6746840 B2 JP 6746840B2 JP 2016105061 A JP2016105061 A JP 2016105061A JP 2016105061 A JP2016105061 A JP 2016105061A JP 6746840 B2 JP6746840 B2 JP 6746840B2
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Description
本発明は、工作機械における刃物台の熱変位による加工誤差の補正方法に関し、特に回転工具の発熱に伴う加工誤差の補正方法に係る。 The present invention relates to a method of correcting a processing error due to thermal displacement of a tool post in a machine tool, and more particularly to a method of correcting a processing error due to heat generation of a rotary tool.
ワークを回転工具等にて加工する際に、回転工具の駆動部の発熱や刃先の加工熱により刃物台が温度上昇する。
これにより刃物台が熱変形し、加工誤差の一因となる。
例えば、タレット旋盤等の工作機械においてはタレットの温度が上昇すると、それに伴いタレット外形が大きくなり、バイト等による旋削加工において加工誤差が生じる要因の１つになる。
これまでに刃物台に温度センサ等を取り付けて、その測定温度に基づいてＮＣ装置の送り指令を補正することが行われているが、タレットのようなインデックス割出し刃物台の場合には配線によるトラブルが発生しやすい。
When machining a workpiece with a rotary tool or the like, the temperature of the tool rest rises due to the heat generated by the drive unit of the rotary tool and the machining heat of the cutting edge.
This causes the tool post to be thermally deformed, which causes a machining error.
For example, in a machine tool such as a turret lathe, if the temperature of the turret increases, the outer shape of the turret increases accordingly, which is one of the factors causing a machining error in turning with a cutting tool or the like.
Up to now, a temperature sensor etc. has been attached to the turret and the feed command of the NC device has been corrected based on the measured temperature. However, in the case of an index indexing turret such as a turret, wiring is required. Trouble is likely to occur.
特許文献１には、温度センサを不要とした工具支持体の熱変化の補正方法を開示するが、単に温度に比例した値の温度情報によるものであり、実用的でなく、また、冷却機構による影響を考慮したものではない。 Patent Document 1 discloses a method for correcting a thermal change in a tool support that does not require a temperature sensor. However, the method is merely based on temperature information having a value proportional to the temperature, is not practical, and uses a cooling mechanism. It does not consider the impact.
本発明は、工作機械の発熱部及び冷却機構を考慮した刃物台の熱変位補正方法の提供を目的とする。 An object of the present invention is to provide a method for correcting thermal displacement of a tool post in consideration of a heat generating part and a cooling mechanism of a machine tool.
本発明に係る刃物台の熱変位補正方法は、回転工具及び非回転工具との複数の工具ステーションを有する刃物台を備え、前記回転工具の加工履歴を記憶する加工履歴記憶手段と、冷却装置の稼働履歴を記憶する冷却履歴記憶手段と、前記加工履歴記憶手段と冷却履歴記憶手段とから前記刃物台に与える温度変化を算出する温度変化演算手段を有し、前記温度変化演算手段にて求めた温度変化の推定値に基づいて加工誤差の補正値を演算する補正値演算手段を有し、前記複数の工具ステーションのうち、いずれか１つの工具を用いてワークを加工する際に前記補正値演算手段にて得られた補正値にてＮＣ装置の送り指令を補正することを特徴とする。
ここで冷却装置の稼働履歴とは、クーラントの循環のＯＮ／ＯＦＦ、流量、クーラントの温度等をいう。
A tool post thermal displacement correction method according to the present invention includes a tool post having a plurality of tool stations of a rotary tool and a non-rotary tool, and a machining history storage unit that stores a machining history of the rotary tool, and a cooling device. It has a cooling history storage means for storing an operation history, and a temperature change calculation means for calculating a temperature change given to the tool post from the processing history storage means and the cooling history storage means, and is obtained by the temperature change calculation means. Compensation value computing means for computing a compensation value of machining error based on an estimated value of temperature change is provided, and the compensation value calculation is carried out when machining a workpiece using any one of the plurality of tool stations. The feed command of the NC device is corrected by the correction value obtained by the means.
Here, the operation history of the cooling device refers to ON/OFF of the circulation of the coolant, the flow rate, the temperature of the coolant, and the like.
ここで、前記複数の工具ステーションに取り付けた各工具間の相互の熱影響関係を算出する位置補正手段を有し、前記温度変化演算手段と前記位置補正手段とから補正値を演算するのが好ましい。
例えば刃物台がタレット刃物台である場合には、それぞれの工具の位置関係によっても熱影響の大きさが変化するからである。
Here, it is preferable to have position correction means for calculating a mutual heat influence relationship between the respective tools attached to the plurality of tool stations, and to calculate a correction value from the temperature change calculation means and the position correction means. ..
This is because, for example, when the turret is a turret turret, the magnitude of the thermal effect changes depending on the positional relationship between the tools.
回転工具としては、ミーリングツール，ドリルツール等が例として挙げられ、非回転工具としてはバイト等の旋削工具が例として挙げられる。 Examples of rotary tools include milling tools and drill tools, and examples of non-rotating tools include turning tools such as cutting tools.
本発明においては、刃物台の温度上昇を回転工具の稼働状況にて算出するとともに冷却装置におけるクーラントの使用状況も考慮したので加工誤差の補正精度が向上する。 In the present invention, the temperature rise of the tool post is calculated based on the operating status of the rotary tool, and the usage status of the coolant in the cooling device is also taken into consideration.
本発明に係る刃物台の構造例を以下、図面に基づいて説明する。 A structural example of the tool rest according to the present invention will be described below with reference to the drawings.
図１（ａ）は、タレットのｍ番目工具ステーション（ｍ番ＳＴ）にミーリングツールを装着し、ｎ番目工具ステーション（ｎ番ＳＴ）に旋削用バイトを装着した例を示す。
このｎ番ＳＴのバイトにてワークを加工する際のＮＣ装置の送り指令の（補正量）ｎは、図１（ｂ）に示した演算式で求めることができる。
FIG. 1A shows an example in which a milling tool is mounted on the m-th tool station (m-th ST) of the turret and a turning tool is mounted on the n-th tool station (n-th ST).
The (correction amount) n of the feed command of the NC device when machining the workpiece with the n-th ST bit can be obtained by the arithmetic expression shown in FIG.
この式でΣとしたのは、複数の回転工具の加工履歴による補正の合成値であることを意味する。
係数αは予め実験に基づいて得られた発熱の程度を表す係数であり、Ｎｍはｍ番ＳＴ回転工具を用いてワークの加工をした際の回転速度である。
βは予め実験で得られた定数である。
Ａｍはｍ番ＳＴ回転工具の稼働率（稼働時間の割合）を示し、Ｎｍ，Ａｍは加工履歴記憶手段に記憶されている。
In this equation, Σ means that it is a combined value of the corrections based on the processing history of the plurality of rotary tools.
The coefficient α is a coefficient representing the degree of heat generation obtained based on experiments in advance, and N m is the rotation speed when the workpiece is processed using the m-th ST rotary tool.
β is a constant obtained in advance by an experiment.
A m indicates the operating rate (ratio of operating time) of the m-th ST rotary tool, and N m and A m are stored in the processing history storage means.
Ｆ×（Ｔｍ−Ｔｃ）の項はクーラントの影響を表す項であり、係数Ｆはクーラントの使用状況に基づく係数であり、Ｔｍはｍ番ＳＴ回転工具でワークを加工した際のタレットの温度であり、Ｔｃはその時のクーラントの温度である。
タレットの温度Ｔｍは測定していないので、回転工具の履歴と周囲の機内雰囲気温度ＴＦから求める。
よって、Ｔｍ＝（α×Ｎｍ＋β）＋ＴＦで求まる。
また、クーラントの使用状況を示す係数Ｆは、クーラントを使用しないときはＦ＝０とし、クーラントを使用しているときは０以外の実数となる。
例えば複数のクーラント流路がある場合に、その経路毎の流量をＶ１，Ｖ２，Ｖ３とすると、トータル流量Ｖに対して、
ここで（Ｆ１，Ｆ２，Ｆ３）は分岐係数である。
以上のことから図１（ｂ）の補正式において、
Ｃｎ，ｍはｎ番ＳＴで加工する際の工具ステーションｍ番ＳＴとｎ番ＳＴとの位置係数である。
またＢはタレットの大きさ、構造について定まる線膨張係数である。
The term F×(T m −T c ) is a term representing the influence of the coolant, the coefficient F is a coefficient based on the usage state of the coolant, and T m is the turret when the workpiece is machined by the m-th ST rotary tool. , And Tc is the temperature of the coolant at that time.
Since the temperature T m of the turret is not measured, it is obtained from the history of the rotary tool and the ambient temperature T F in the machine.
Therefore, it can be calculated by T m =(α×N m +β)+T F.
Further, the coefficient F indicating the usage state of the coolant is F=0 when the coolant is not used and is a real number other than 0 when the coolant is used.
For example, when there are a plurality of coolant flow paths, and the flow rates for the respective paths are V 1 , V 2 , and V 3 , the total flow rate V is
Here, (F 1 , F 2 , F 3 ) is a branching coefficient.
From the above, in the correction formula of FIG.
C n and m are position coefficients of the tool stations m-th ST and n-th ST when machining is performed with the n-th ST.
B is a coefficient of linear expansion that is determined by the size and structure of the turret.
クーラントの影響を実験で確認したので説明する。
図２（ａ）は回転工具を用いて４時間連続加工その後に３０分中断し、さらに４時間加工した（横軸）際のクーラント温度変化量を示す。
実線は温度コントロールしない時のクーラントの温度変化を示し、点線は温度コントロールした時のクーラントの温度の推移を示す。
図２（ｂ）は上記それぞれのクーラントの温度状況に対するｎ番ＳＴの熱変位量を示す。
クーラントの温度が変化した実線のチャートの方がクーラントの温度を一定した点線のチャートよりも変位量が大きく、クーラントの使用状況を考慮することで補正精度が向上することが明らかになった。
The effect of the coolant was confirmed by experiments, so I will explain it.
FIG. 2A shows a coolant temperature change amount when a rotary tool is used for continuous working for 4 hours, then interrupted for 30 minutes, and further processed for 4 hours (horizontal axis).
The solid line shows the temperature change of the coolant when the temperature is not controlled, and the dotted line shows the change of the temperature of the coolant when the temperature is controlled.
FIG. 2B shows the amount of thermal displacement of the n-th ST with respect to the temperature conditions of the above coolants.
It has been clarified that the solid line chart in which the coolant temperature has changed has a larger displacement amount than the dotted line chart in which the coolant temperature is constant, and the correction accuracy is improved by considering the usage state of the coolant.
Claims (2)
前記ＮＣ装置は、前記回転工具の加工履歴を記憶する加工履歴記憶手段と、冷却装置の稼働履歴を記憶する冷却履歴記憶手段と、前記加工履歴記憶手段と冷却履歴記憶手段及び、刃物台周囲の雰囲気温度から前記刃物台に与える温度変化を算出する温度変化演算手段を有し、且つ、前記温度変化演算手段にて求めた温度変化の推定値に基づいて加工誤差の補正値を演算する補正値演算手段を有し、
前記ＮＣ装置は、前記複数の工具ステーションに取り付けた各工具間の相互の熱影響関係を算出する位置補正手段を有し、前記複数の工具ステーションのうち、いずれか１つの工具を用いてワークを加工する際に前記温度変化演算手段と前記位置補正手段とから補正値を演算して得られた補正値にて前記ＮＣ装置の送り指令を補正することを特徴とする刃物台の熱変位補正方法。 A tool post having a plurality of tool stations for rotating tools and non-rotating tools; and an NC device for controlling movement of the tool post ,
The NC device includes a machining history storage unit that stores a machining history of the rotary tool, a cooling history storage unit that stores an operation history of a cooling device, the machining history storage unit and a cooling history storage unit, and a tool post periphery. A correction value having a temperature change calculation means for calculating a temperature change given to the tool post from an ambient temperature , and for calculating a correction value of a processing error based on an estimated value of the temperature change obtained by the temperature change calculation means. Has a computing means,
The NC device has position correction means for calculating a mutual thermal influence relationship between the respective tools attached to the plurality of tool stations, and a work is prepared by using any one tool of the plurality of tool stations. the temperature change computing means and the position correcting means and the NC device feed command knives stand thermal displacement correction and correcting the at correction value obtained by calculating the correction value from the time of processing Method.
The tool rest according to claim 1 Symbol placement tool rest thermal displacement correction method for characterized in that it is a turret.
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| US5421683A (en) * | 1993-06-17 | 1995-06-06 | National Broach & Machine Company | Machine tool with temperature compensation |
| JPH11338527A (en) * | 1998-05-28 | 1999-12-10 | Makino Milling Mach Co Ltd | Machine tool control method and device |
| JP2002036069A (en) * | 2000-07-28 | 2002-02-05 | Okuma Corp | Thermal displacement compensation method |
| JP2002301637A (en) * | 2001-04-05 | 2002-10-15 | Okuma Corp | Thermal displacement compensation method for machine tools |
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