JP4033001B2 - Grinding equipment - Google Patents

Description

【００２２】
上記（１）式において、電力効率ηの値には研削装置のテストを行うことにより得られた数値が用いられている。また、砥石１及び内輪素材３の周速度Ｖｓの値及び周速度Ｖｗの値は、例えば研削加工開始時にＷ／Ｈ ２１に装着されている砥石１のタイプ番号、加工対象の素材型番などの研削情報が制御ユニット５に入力されたときに、その入力された研削情報に関連付けられて上記データ記憶部に記憶されている複数の値から当該研削加工に応じた値が自動的に選択されるようになっている。また、上記周速度Ｖｓの値は、砥石１の摩耗状況等に応じて適宜行われるドレス作業の実施回数に応じて自動的に更新されるものであり、上記実施回数に応じて砥石径が小さくなったときでの最適な周速度Ｖｓの値が選択されるようになっている。
【００２３】
上記第１及び第２の補正手段５２ａ２，５２ｂ２は、それぞれ対応する変換手段５２ａ１，５２ｂ１からの研削力成分値にフィードバックゲインＫｂ及びフィードフォワードゲインＫｆを乗算することにより、対応する研削力成分値の補正値を求めて出力する。上記フィードバックゲインＫｂは、研削装置のテストを行うことにより得られた当該装置固有の値であり、上記データ記憶部に予め記憶された固定値である。また、フィードフォワードゲインＫｆは、加工対象の素材３等に応じて変更される可変値であり、テストピースを用いた試験結果に応じて外乱等の影響を排除することが可能な最適な値が適宜選ばれるようになっている。
【００２４】
上記研削力−速度変換手段５２ｅは、第１及び第２の補正手段５２ａ２，５２ｂ２からの各補正値と、積分部５２ｃ及び微分部５２ｄからの各出力値との加算値を入力し、この加算値と予め設定された速度変換ゲインＫｃとの積の値を所定の演算式により速度に変換し、砥石１の研削速度についての指示速度Ｖｃを決定し切込み台制御部５３に出力する。具体的には、研削力−速度変換手段５２ｅは、次の演算式、上記加算値×Ｋｃ＋Ｆ（ｒ）（Ｆ（ｒ）は砥石径をパラメータとする関数値）により、指示速度Ｖｃを算出している。上記速度変換ゲインＫｃは、上記フィードバックゲインＫｂと同様に研削装置固有の値であり、上記データ記憶部に予め記憶された固定値である。
上記切込み台制御部５３は、切込みモータ４２への供給電流をコントロールするドライバを含んで構成されたものであり、同モータ４２での回転速度が研削力−速度変換手段５２ｅからの指示速度Ｖｃと一致するように支持機構部４の駆動制御を行う。これにより、制御ユニット５は、その目標電力設定部５１に設定された研削電力に対応した最適な研削速度にて素材加工面３ａに対する研削加工を行うことができる。
【００２５】
以上のように、本実施形態の研削装置では、フィードバック調整部５２ａのゲイン出力値だけでなく、フィードフォワード調整部５２ｂのゲイン出力値を用いて、制御ユニット５が砥石１の研削速度を制御しているので、上記指示速度Ｖｃに対する砥石研削速度の応答性を向上させることができる。つまり、フィードバック制御のみで研削速度を制御していた上記従来例では、設定目標値の変化の影響が検出値に現れるまでの時間、すなわち少なくとも一回のフィードバックループを実行させた後の検出値を取得するまでの時間を無駄にしていた。これに対して、本実施形態では、フィードバック調整部５２ａとフィードフォワード調整部５２ｂとを併用することにより、一回のフィードバックループ実行後の検出値を取得するまでの無駄な待機時間を省略することができ、電力目標値Ｐｃを電力検出値Ｐｒに早急に近づけ一致させることができる。この結果、砥石１の研削速度を所望速度に即座に変更することが可能となって、電力目標値Ｐｃと電力検出値Ｐｒとの差が大きい場合などでも、内輪素材（ワーク）３の処理時間の短縮化を確実に行うことができる。
【００２６】
また、本実施形態では、第１及び第２の補正手段５２ａ２，５２ｂ２が、適切なフィードバックゲインＫｂ及びフィードフォワードゲインＫｆを用いて、対応する第１及び第２の電力−研削力変換手段５２ａ１，５２ｂ１からの研削力成分値を補正し、さらに研削力−速度変換手段５２ｅが、適切な速度変換ゲインＫｃを用いて、入力した研削力成分値を補正して、指示速度Ｖｃを決定している。この結果、本実施形態では、上記の応答性の向上に加えて、研削装置でのロバスト性及び内輪素材３に対する加工精度を向上させることができる。また、研削力−速度変換手段５２ｅが積分部５２ｃからの出力値を用いて指示速度Ｖｃを決定することにより、電力目標値Ｐｃに対する定常偏差を小さくすることができるとともに、当該変換手段５２ｅが微分部５２ｄからの出力値を用いて指示速度Ｖｃを決定することにより、上記応答性をさらに向上させることができる。
【００２７】
また、上記フィードバックゲインＫｂ、フィードフォワードゲインＫｆ、及び速度変換ゲインＫｃのうち、フィードフォワードゲインＫｆのみ可変値とすることにより、これらのゲイン設定操作を簡単化して、ワーク研削加工を容易に行うことができる。尚、本願発明者等の実験によれば、固定的なフィードバックゲインＫｂや速度変換ゲインＫｃを用いた場合でも、優れた応答性を確保した状態で研削加工を高速に行えることが確認されている。
【００２８】
ここで、本願の発明者等が実施した比較試験の結果例について、図４を参照して具体的に説明する。
図４（ａ）及び（ｂ）はそれぞれ本実施形態品及び従来品での検出結果を示す波形図である。尚、図４（ｂ）に示すグラフは、上記研削速度を一定速度とした定速研削方式の従来品での試験結果である。この比較試験は、研削加工前のワーク加工面状態が粗い（悪い）もの、つまり研削加工初期段階での電力目標値Ｐｃと電力検出値Ｐｒとの差が大きいものに対し実施したものであり、上記文献公知発明品の試験結果は上記定速研削方式の従来品のものよりワーク加工時間に長い時間を要したので、その文献公知発明品の結果については省略する。
上記従来品では、同図（ｂ）の検出電力波形７２に示すように、研削電力は黒皮及び粗工程での立ち上がり速度が遅いものであった。
【００２９】
これに対して、本実施形態品では、図４（ａ）の検出電力波形７１に示すように、研削電力は砥石１の研削負荷の変化に応じて黒皮及び粗工程で急峻に立ち上がって加工がワークに行われるとともに、上記従来品よりも短い時間（９０％以下）でワーク加工を終了することができ、目標電力に対する応答性が向上されていることが確認された。また、電子顕微鏡による表面検査を実施したところ、本実施形態品の方が、従来品よりもはるかに仕上がり品質が向上されていることが確認された。つまり、本実施形態品は、上記黒皮工程などの各工程において、ワーク加工面の加工状態などを反映した最適な研削速度による加工を安定した状態で確実に行えることが実証された。
【００３０】
尚、上記の説明では、内輪用の研削装置に適用した場合について説明したが、本発明は上記フィードバック制御に加えフィードフォワード制御を行うフィードフォワード補償型２自由度制御方式により、上記研削速度を制御するものであれば何等限定されるものではなく、外輪外周面などの他の加工面に研削加工を施す各種工作機械に適用することができる。
また、上記の説明では、電動モータ２２での研削電力を検出し研削速度を制御する構成について説明したが、上記駆動機構部２に歪み計などを設けて内輪素材３から砥石１に作用する研削抵抗値を上記研削力の成分値として検出し研削速度を制御してもよい。この場合には、上記第１及び第２の電力−研削力変換手段５２ａ１，５２ｂ１を割愛することができる。但し、上記歪み計などを含む検出機構は、一般的には電流計等を含んだ上記電力検出部６よりも構造が複雑であり、研削装置を大型化することから、研削電力を用いた方が当該装置構成を簡略化できる点で好ましい。
また、上記の説明では、フィードバック調整部５２ａとこの調整部５２ａからの出力値をそれぞれ積分及び微分する積分部５２ｃ及び微分部５２ｄを備えたＰＩＤ方式の構成について説明したが、本発明はこれに限定されるものではなく、上記微分部５２ｄを割愛したＰＩ方式または積分部５２ｃ及び微分部５２ｄを割愛したＰ方式のものでもよい。
【００３１】
【発明の効果】
本発明の研削装置によれば、ワークの研削加工に応じて設定された設定値に対する応答性を向上させることができ、ワーク処理時間を確実に短縮することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る研削装置の要部構成例を示す模式図である。
【図２】図１に示した研削装置の要部構成例を示すブロック図である。
【図３】図２に示した適応制御部の構成例を示すブロック図である。
【図４】比較試験における砥石回転用電動モータの研削電力の検出波形の具体例を示すグラフであって、（ａ）及び（ｂ）はそれぞれ本実施形態品及び従来品での検出結果を示す波形図である。
【符号の説明】
１ 砥石
３ 内輪素材（ワーク）
５ 制御ユニット（制御部）
５２ａ フィードバック調整部
５２ａ１ 第１の電力−研削力変換手段
５２ａ２ 第１の補正手段
５２ｂ フィードフォワード調整部
５２ｂ１ 第２の電力−研削力変換手段
５２ｂ２ 第２の補正手段
５２ｅ 研削力−速度変換手段
２２ 電動モータ
Ｐｃ （研削電力の）電力目標値
Ｐｒ （研削電力の）電力検出値
Ｋｂ フィードバックゲイン
Ｋｆ フィードフォワードゲイン
Ｋｃ 速度変換ゲイン[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grinding apparatus for grinding a work such as a raceway.
[0002]
[Prior art]
For example, in a grinding device that grinds an inner ring material, the same material is rotated, and a grindstone rotated at a constant rotational speed by an electric motor is inserted into a through-hole formed in the material. ) To be finished into an inner ring having a desired inner peripheral surface. In addition, such a grinding apparatus supports the material so as to be movable with respect to the grindstone. Conventional grinding apparatuses generally perform constant speed grinding by bringing the material close to the grindstone at a constant speed. It was broken. However, in such constant-speed grinding, the workpiece is cycled at a constant grinding speed regardless of the machining state of the inner ring material (workpiece) on the machining surface. It was difficult to shorten the time and improve the quality of the workpiece.
[0003]
Some conventional grinding apparatuses perform adaptive control that appropriately changes the grinding speed based on the grinding force of a grindstone on a workpiece (see, for example, Patent Document 1).
Specifically, this conventional apparatus is provided with detection means including an ammeter or detection means including a strain sensor, and power consumption by the electric motor as the grinding force or contact resistance acting on the grindstone from the workpiece. The grinding speed is adjusted to the desired speed by detecting (grinding resistance) and performing feedback control to bring these detected values close to the set target values.
[0004]
[Patent Document 1]
Japanese Patent No. 3362952 (pages 5-7, FIG. 1)
[0005]
[Problems to be solved by the invention]
However, in the conventional apparatus as described above, it may take a long time to make the detected value coincide with the target value when the difference between the detected value from the detecting means and the set target value is large. . As a result, the time required from the start of the grinding process to the time when the machining with the desired grinding force is performed becomes longer, and the processing time of the workpiece grinding process, and thus the cycle time of the workpiece may not be shortened. .
[0006]
In view of the conventional problems as described above, the present invention provides a grinding apparatus with excellent responsiveness that can reliably reduce the work processing time.
[0007]
[Means for Solving the Problems]
The present invention is a grinding apparatus comprising a control unit that feedback-controls the grinding speed of the grinding wheel with respect to the workpiece based on a detected value of the grinding force with respect to the workpiece of the grinding wheel that is rotationally driven by an electric motor and the target value thereof,
The control unit uses the grinding power of the electric motor as the grinding force , the target value of grinding power is Pc, the power efficiency peculiar to the grinding device is η, and the peripheral speed of the grinding wheel is a value based on the grinding wheel diameter is Vs. [M / min ], when the peripheral speed of the workpiece is Vw [m / min ],
Ft = Pc × {60η / (Vs−Vw)}
The grinding speed is feedforward controlled based on the component value Ft in the tangential direction of the grinding force obtained by the above.
[0008]
In the control unit in the grinding apparatus configured as described above, the grinding speed of the grindstone is determined not only by feedback control but also by feedforward control based on the component value Ft. Can increase the sex. Therefore, it is possible to immediately change the grinding speed of the grindstone to a desired speed and shorten the work processing time. Further, the change in the peripheral speed Vs based on the grindstone diameter can be reflected in the component value Ft.
[0009]
Further, it becomes possible to grind speed of the abrasive stone is controlled based on the grinding power of the electric motor, there is no need to provide a detector such as a grinding device for directly measuring the grinding force, simplify the device configuration Can be
[0010]
In the grinding apparatus, the control unit
A first power-grinding force converting means for converting a value of a difference between a detected value of the grinding power by the electric motor and a target value into a grinding force at a contact point between the grindstone and the workpiece , and a feedback gain; A feedback adjustment unit having first correction means for correcting the output of the first power-grinding force conversion means by using;
A feedforward adjustment unit having second power-grinding force conversion means for obtaining the component value Ft , and second correction means for correcting the component value Ft using a feedforward gain ;
Wherein the control unit, by using the correction values from the first and second correction means, grinding power seek instruction speed of the grinding speed of the grinding wheel - preferably comprises a speed conversion means.
In this case, by making the values of the feedback gain and the feed forward gain and the value of the speed conversion gain in the grinding force-speed conversion means appropriate, in addition to the above responsiveness, the robustness in the grinding apparatus In addition, the machining accuracy for the workpiece can be improved.
[0011]
In the grinding apparatus, the feedforward gain may be a variable value.
In this case, by performing an actual machine test using a test piece before the workpiece is ground, a feedforward gain capable of eliminating the influence of disturbance or the like can be appropriately determined and set.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a grinding apparatus of the present invention will be described with reference to the drawings. In the following description, a case where the present invention is applied to an inner ring grinding apparatus will be described as an example in order to facilitate comparison with the conventional example.
FIG. 1 is a schematic diagram showing a configuration example of a main part of a grinding apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a configuration example of a main part of the grinding apparatus.
In FIG. 1, the grinding apparatus according to the present embodiment includes a drive mechanism unit 2 that rotationally drives a grindstone 1, a support mechanism unit 4 that supports an inner ring material 3 as a workpiece, and each drive of these mechanism units 2 and 4. And a control unit 5 as a control unit that performs control, and the material processing is performed by the grindstone 1 appropriately selected according to the material of the material 3, the state of the processed surface of the material 3, the shape dimensions, and the like. It can be applied to the surface.
The drive mechanism unit 2 is configured to be slidable in the left-right direction in FIG. 1. When grinding the inner ring material 3, the drive mechanism unit 2 is moved as shown by a broken arrow in FIG. It moves to the processing position where the grindstone outer peripheral surface can be brought into contact with the material inner peripheral surface 3a as the processing surface. Further, the drive mechanism 2 moves to the retracted position shown in FIG. 1 so that the replacement work of the grindstone 1 and the inner ring material 3 can be easily performed.
[0013]
Further, the driving mechanism 2 is detachably mounted with the grindstone 1 on one end side, and is also rotatably supported by a bearing means (not shown) as a wheel head (hereinafter referred to as “W / H”). .) 21 and a driving electric motor 22 for rotationally driving the W / H 21 are provided. The electric motor 22 is constituted by an AC motor driven by an inverter. A first pulley 23 and a second pulley 24 are attached to the other end of the W / H 21 and the output shaft of the electric motor 22 so as to be integrally rotatable. These first and second pulleys 23 and 24 are belted around a belt 25. When the motor 22 rotates in response to an operation command from the control unit 5, the drive mechanism 2 rotates the belt 25. The force is transmitted to the W / H 21 and the W / H 21 and the grindstone 1 are rotationally driven at a constant speed in the P direction of FIG. Further, in this mechanism portion 2, the rotational operation of the grindstone 1 is stabilized by the W / H 21, and the grinding process by the grindstone 1 can be performed in a stable state. Furthermore, by changing the outer diameters of the first and second pulleys 23 and 24 and adjusting their pulley ratios, it is possible to change the rotational speed of the grindstone 1 even when the same motor 22 is used. ing.
[0014]
The support mechanism unit 4 includes a cutting base 41 and a cutting motor 42 connected to the cutting base 41 via a ball screw type coupling mechanism (not shown). The cutting speed (grinding speed) of the grindstone 1 with respect to the inner ring material 3 can be changed by rotating the motor 42 in accordance with the speed command. More specifically, the cutting table 41 includes a magnet chuck that holds the inner ring material 3 in a rotatable state, and a work rotation motor that rotates the material 3 held by the magnet chuck in the Q direction in FIG. Is provided (not shown). Then, when the cutting motor 42 rotates in the R direction in FIG. 1, the cutting base 41 is moved in the S direction in FIG. Accordingly, the rotating inner ring material 3 is also pushed in the S direction along with the movement of the cutting table 41, and the contact (grinding) position between the processing surface 3a and the grindstone 1 is moved in the S direction. As a result, the cutting amount (grinding amount) of the grindstone 1 with respect to the processing surface 3a is changed, and the grinding speed of the grindstone 1 is also changed by changing the rotation speed of the cutting motor 42.
[0015]
The control unit 5 is configured to control the grinding speed based on the grinding power of the electric motor 1 as the grinding force of the grindstone 1 against the inner ring material 3, and is configured by a nonvolatile memory or the like. In accordance with a grinding program stored in a data storage unit (not shown), a plurality of stepped grinding processes having different grinding speeds, such as indexing, semi-quick, black skin, rough, finishing, and finishing SP The (spark out) process is sequentially performed on the inner ring material 3. Thereby, after the inner ring material 3 is brought into contact with the grindstone 1 at the end of the semi-urgent process from the non-contact state with the grindstone 1 in the indexing process, the inner ring material 3 is substantially substantiated by the grindstone 1 in the black skin, roughing and finishing processes. Grinding is performed on the processed surface 3a, and the contact state with the grindstone 1 is released at the end of the finishing SP step.
[0016]
Further, referring to FIG. 2, the control unit 5 includes a target power setting unit 51 to which the power target value of the grinding power is input by an operator, a power target value from the setting unit 51, and an ammeter. The power consumption of the electric motor 22 from the power detection unit 6 is input, and an adaptive control unit 52 that determines an instruction speed related to the grinding speed using these input values, and an instruction signal from the control unit 52 Correspondingly, a cutting table control unit 53 that controls the driving of the cutting motor 42 is provided.
Further, in the control unit 5, other detection means provided in a grinding apparatus or a production line other than the power detection unit 6, for example, a sensor indicating a supply state of a cooling medium (coolant) supplied to the grinding position. A detection signal is input, and the adaptive control unit 52 appropriately performs grinding using the detected data as appropriate. Further, the control unit 5 is provided with data transmission / reception means having a display function such as a touch panel. The control unit 5 receives input instructions from the operator to the adaptive control unit 52 and new program data, and detection data of the detection means. It is possible to transmit data indicating the status of the grinding process including, and the operator can monitor the necessary information displayed on the panel or the like. The data transmission / reception means may be configured to include the target power setting unit 51.
[0017]
The adaptive control unit 52 is configured by a CPU or the like that can execute the program, and among the power consumption of the electric motor 22 from the power detection unit 6, the grinding power excluding no-load power (that is, The value of the load power that varies according to the grinding load on the grindstone 1 is extracted and acquired. The adaptive control unit 52 performs the feedback control using the detected value of the grinding power and the target value from the target setting unit 51 and the feedforward control using the target value, thereby performing the process from the black skin process to the finishing process. The grinding surface 3a can be processed by optimally determining the grinding speed in each grinding process. Further, the adaptive control unit 52 can appropriately detect the contact between the grindstone 1 and the material 3 in the semi-urgent process and the separation operation of the grindstone 1 from the material 3 in the finishing SP process using the detected value of the grinding power. It is configured.
In the above description, the configuration in which the adaptive control unit 52 extracts the detected value of the grinding power from the power consumption has been described. However, the power detection unit 6 performs the extraction operation, and the processing load in the control unit 52 is increased. It may be configured to reduce the above.
[0018]
Specifically, as shown in FIG. 3, the adaptive control unit 52 includes a feedback adjustment unit 52a that receives the power target value Pc and the power detection value Pr of the grinding power, and a feed that receives the power target value Pc. And a forward adjustment unit 52b. Further, the control unit 52 is provided with an integration unit 52c and a differentiation unit 52d that perform integration processing and differentiation processing on the output value from the feedback adjustment unit 52a using the integration constant I and the differentiation constant D, respectively. The integration unit 52c, the differentiation unit 52d, and the feedback adjustment unit 52a perform PID control. Further, the adaptive control unit 52 uses the output values from the feedback adjustment unit 52a, the feedforward adjustment unit 52b, the integration unit 52c, and the differentiation unit 52d to indicate an instruction speed as an instruction signal to the cutting base control unit 53. Grinding force-speed converting means 52e for generating Vc is provided.
[0019]
The feedback adjusting unit 52a converts the difference value between the input power detection value Pr and the power target value Pc into a component value of the tangential grinding force at the contact point between the grindstone 1 and the inner ring material 3. First power-grinding force converting means 52a1 and first correcting means 52a2 for correcting the grinding force component value from the first power-grinding force converting means 52a1 using the feedback gain Kb are provided. The correction value from the correction means 52a2 is output as a gain output value corresponding to the grinding power.
The feedforward adjustment unit 52b includes a second power-grinding force conversion means 52b1 that converts the input power target value Pc into a tangential grinding force component value at the contact point of the grindstone 1; There is provided second correction means 52b2 for correcting the grinding force component value from the second power-grinding force conversion means 52b1 using the feedforward gain Kf, and the correction value from the correction means 52b2 is ground. Output as a gain output value according to the power.
[0020]
In the first and second power-grinding force conversion means 52a1 and 52b1, the input power target value Pc or this target value Pc is determined according to the following formula (1) established at the contact point between the grindstone 1 and the inner ring material 3. And the component value in the tangential direction of the target grinding force from the grinding power value determined by the power detection value Pr. That is, at the contact point, the loss value of the grinding power P per second is expressed by the component value in the tangential direction of the grinding force with which the grindstone 1 grinds the inner ring material 3 (component value in the same direction of the grinding resistance) Ft. Since it is equal to the product of the difference between the peripheral speeds of the grindstone 1 and the inner ring material 3, the power efficiency inherent to the grinding device is η, and the peripheral speeds of the grindstone 1 and the inner ring material 3 are Vs (m / min) and Vw ( m / min), equation (1) is established.
[0021]
[Expression 1]

[0022]
In the above equation (1), the value obtained by testing the grinding apparatus is used as the value of the power efficiency η. The values of the peripheral speed Vs and the peripheral speed Vw of the grindstone 1 and the inner ring material 3 are, for example, the grinding of the type number of the grindstone 1 mounted on the W / H 21 at the start of the grinding process, the material model number to be processed, and the like. When information is input to the control unit 5, a value corresponding to the grinding process is automatically selected from a plurality of values associated with the input grinding information and stored in the data storage unit. It has become. Further, the value of the circumferential speed Vs is automatically updated according to the number of times of dressing work appropriately performed according to the wear state of the grindstone 1 and the diameter of the grindstone is small according to the number of times of execution. The optimum value of the peripheral speed Vs at that time is selected.
[0023]
The first and second correction means 52a2 and 52b2 multiply the grinding force component values from the corresponding conversion means 52a1 and 52b1 by the feedback gain Kb and the feedforward gain Kf, respectively, thereby obtaining the corresponding grinding force component values. Find the correction value and output it. The feedback gain Kb is a value unique to the device obtained by testing the grinding device, and is a fixed value stored in advance in the data storage unit. The feedforward gain Kf is a variable value that is changed according to the material 3 to be processed, and an optimum value that can eliminate the influence of disturbance or the like according to the test result using the test piece. It is chosen as appropriate.
[0024]
The grinding force-speed converting means 52e inputs an addition value of each correction value from the first and second correction means 52a2 and 52b2 and each output value from the integration section 52c and the differentiation section 52d, and this addition A product value of the value and a preset speed conversion gain Kc is converted into a speed by a predetermined arithmetic expression, and an instruction speed Vc for the grinding speed of the grindstone 1 is determined and output to the notch table control unit 53. Specifically, the grinding force-speed converting means 52e calculates the instruction speed Vc by the following arithmetic expression, the above addition value × Kc + F (r) (F (r) is a function value with the grindstone diameter as a parameter). ing. The speed conversion gain Kc is a value unique to the grinding apparatus, like the feedback gain Kb, and is a fixed value stored in advance in the data storage unit.
The incision table control unit 53 includes a driver that controls the current supplied to the incision motor 42, and the rotational speed of the motor 42 is equal to the instruction speed Vc from the grinding force-speed conversion means 52e. Drive control of the support mechanism unit 4 is performed so as to match. As a result, the control unit 5 can perform grinding on the material processing surface 3a at an optimum grinding speed corresponding to the grinding power set in the target power setting unit 51.
[0025]
As described above, in the grinding apparatus of this embodiment, the control unit 5 controls the grinding speed of the grindstone 1 using not only the gain output value of the feedback adjustment unit 52a but also the gain output value of the feedforward adjustment unit 52b. Therefore, the responsiveness of the grinding wheel grinding speed to the indicated speed Vc can be improved. That is, in the above conventional example in which the grinding speed is controlled only by feedback control, the time until the influence of the change in the set target value appears in the detection value, that is, the detection value after executing at least one feedback loop is calculated. Was wasting time to get. On the other hand, in the present embodiment, by using the feedback adjustment unit 52a and the feedforward adjustment unit 52b in combination, useless waiting time until obtaining a detection value after one feedback loop execution is omitted. The power target value Pc can be brought close to the power detection value Pr quickly and matched. As a result, the grinding speed of the grindstone 1 can be immediately changed to a desired speed, and even when the difference between the power target value Pc and the power detection value Pr is large, the processing time of the inner ring material (work) 3 is increased. Can be reliably shortened.
[0026]
In the present embodiment, the first and second correction means 52a2 and 52b2 use the appropriate feedback gain Kb and feedforward gain Kf, and the corresponding first and second power-grinding force conversion means 52a1. The grinding force component value from 52b1 is corrected, and the grinding force-speed converting means 52e corrects the input grinding force component value by using an appropriate speed conversion gain Kc to determine the command speed Vc. . As a result, in this embodiment, in addition to the improvement of the responsiveness described above, it is possible to improve the robustness in the grinding apparatus and the processing accuracy for the inner ring material 3. Further, the grinding force / speed converting means 52e determines the command speed Vc using the output value from the integrating section 52c, so that the steady deviation with respect to the power target value Pc can be reduced, and the converting means 52e is differentiated. The responsiveness can be further improved by determining the instruction speed Vc using the output value from the unit 52d.
[0027]
In addition, by setting only the feedforward gain Kf as a variable value among the feedback gain Kb, the feedforward gain Kf, and the speed conversion gain Kc, these gain setting operations can be simplified and workpiece grinding can be easily performed. Can do. In addition, according to experiments by the inventors of the present application, it has been confirmed that grinding can be performed at high speed while ensuring excellent responsiveness even when a fixed feedback gain Kb or speed conversion gain Kc is used. .
[0028]
Here, an example of the result of the comparison test performed by the inventors of the present application will be specifically described with reference to FIG.
FIGS. 4A and 4B are waveform diagrams showing detection results of the present embodiment product and the conventional product, respectively. Note that the graph shown in FIG. 4B is a test result of a conventional product of the constant speed grinding method in which the grinding speed is constant. This comparative test was performed on a workpiece having a rough (poor) workpiece surface state before grinding, that is, one having a large difference between the power target value Pc and the power detection value Pr in the initial stage of grinding. Since the test result of the above-mentioned literature known invention product requires longer work processing time than that of the conventional product of the above-mentioned constant speed grinding method, the result of the literature known invention product is omitted.
In the conventional product, as shown in the detected power waveform 72 in FIG. 4B, the grinding power has a slow rise rate in the black skin and the roughing process.
[0029]
On the other hand, in this embodiment product, as shown in the detected power waveform 71 of FIG. 4A, the grinding power rises sharply in the black skin and the roughing process according to the change in the grinding load of the grindstone 1 and is processed. It was confirmed that the workpiece machining could be completed in a shorter time (90% or less) than the conventional product, and the responsiveness to the target power was improved. In addition, when surface inspection was performed using an electron microscope, it was confirmed that the finished product had a much improved finish quality than the conventional product. In other words, it was proved that the product of this embodiment can reliably perform the machining at the optimum grinding speed reflecting the machining state of the workpiece machining surface in each process such as the black skin process.
[0030]
In the above description, the case where the present invention is applied to a grinding device for an inner ring has been described. However, the present invention controls the grinding speed by a feed forward compensation type two-degree-of-freedom control system that performs feed forward control in addition to the feedback control. The present invention is not limited in any way, and can be applied to various machine tools that grind other processed surfaces such as the outer peripheral surface of the outer ring.
In the above description, the configuration in which the grinding power is detected by the electric motor 22 and the grinding speed is controlled has been described. However, the driving mechanism 2 is provided with a strain gauge and the like, and the grinding acts on the grindstone 1 from the inner ring material 3. The resistance value may be detected as a component value of the grinding force to control the grinding speed. In this case, the first and second power-grinding force conversion means 52a1 and 52b1 can be omitted. However, the detection mechanism including the strain gauge and the like is generally more complicated in structure than the power detection unit 6 including an ammeter and the like. Is preferable in that the device configuration can be simplified.
In the above description, the configuration of the PID system including the feedback adjustment unit 52a and the integration unit 52c and the differentiation unit 52d for integrating and differentiating the output values from the adjustment unit 52a has been described. However, the present invention is not limited to this, and the PI method in which the differentiating unit 52d is omitted or the P method in which the integrating unit 52c and the differentiating unit 52d are omitted may be used.
[0031]
【The invention's effect】
According to the grinding device of the present invention, it is possible to improve the responsiveness to the set value set in accordance with the workpiece grinding process, and to reliably reduce the workpiece processing time.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a configuration example of a main part of a grinding apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration example of a main part of the grinding apparatus shown in FIG.
3 is a block diagram illustrating a configuration example of an adaptive control unit illustrated in FIG. 2;
FIGS. 4A and 4B are graphs showing specific examples of a detection waveform of grinding power of an electric motor for rotating a grinding wheel in a comparative test, and FIGS. 4A and 4B show detection results of the present embodiment product and a conventional product, respectively. It is a waveform diagram.
[Explanation of symbols]
1 Whetstone 3 Inner ring material (work)
5 Control unit (control unit)
52a Feedback adjustment unit 52a1 First power-grinding force conversion unit 52a2 First correction unit 52b Feedforward adjustment unit 52b1 Second power-grinding force conversion unit 52b2 Second correction unit 52e Grinding force-speed conversion unit 22 Electric Motor Pc Power target value Pr (for grinding power) Power detection value Pr (for grinding power) Kb Feedback gain Kf Feed forward gain Kc Speed conversion gain

Claims (3)

A grinding device comprising a control unit that feedback-controls a grinding speed of the grinding wheel with respect to the workpiece based on a detected value of the grinding force on the workpiece of the grinding wheel rotated by an electric motor and a target value thereof,
The control unit uses the grinding power of the electric motor as the grinding force , the target value of grinding power is Pc, the power efficiency peculiar to the grinding device is η, and the peripheral speed of the grinding wheel is a value based on the grinding wheel diameter is Vs. [M / min ], when the peripheral speed of the workpiece is Vw [m / min ],
Ft = Pc × {60η / (Vs−Vw)}
A grinding apparatus characterized in that the grinding speed is feedforward controlled based on a component value Ft in the tangential direction of the grinding force obtained by the above. The controller is
A first power-grinding force converting means for converting a value of a difference between a detected value of the grinding power by the electric motor and a target value into a grinding force at a contact point between the grindstone and the workpiece, and a feedback gain; A feedback adjustment unit having first correction means for correcting the output of the first power-grinding force conversion means by using;
A feedforward adjustment unit having second power-grinding force conversion means for obtaining the component value Ft, and second correction means for correcting the component value Ft using a feedforward gain;
Grinding force-speed converting means for obtaining an instruction speed for the grinding speed of the grindstone using the correction values from the first and second correcting means.
The grinding apparatus according to claim 1, comprising: The grinding apparatus according to claim 2, wherein the feedforward gain is a variable value .

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