Abstract: A machine tool includes a number-of-same-rotation-speed-cutting-passes computing section that decides the number of same rotation speed cutting passes. The number-of-same-rotation-speed-cutting-passes computing section determines the cutting mode of a threading process based on a set machining program etc., and automatically decides an optimal number of same rotation speed cutting passes according to the cutting mode. Thus, even unskilled operators can easily suppress chatter vibrations, and can easily use the machine tool.

Abstract: A thread cutting machine for cutting a thread by rotating a main spindle and moving a feed axis includes a main-spindle speed computing section that computes and outputs a rotation speed of the main spindle based on a main-spindle rotation speed instruction for each thread cutting pass, and an acceleration/deceleration time computing section that computes and outputs an acceleration/deceleration delay time of the feed axis for each thread cutting pass so that a product of multiplication of the acceleration/deceleration delay time of the feed axis and the rotation speed of the main spindle is the same for all thread cutting passes.

Abstract: A numerical control machine estimates a future rotational speed ahead by a delay time that is a phase difference between a rotational speed fluctuation of a main spindle and a feed rate fluctuation of a feed axis, and fluctuates the feed rate such that a constant ratio is maintained with the estimated rotational speed.

Abstract: A machine tool includes a number-of-same-rotation-speed-cutting-passes computing section that decides the number of same rotation speed cutting passes. The number-of-same-rotation-speed-cutting-passes computing section determines the cutting mode of a threading process based on a set machining program etc., and automatically decides an optimal number of same rotation speed cutting passes according to the cutting mode. Thus, even unskilled operators can easily suppress chatter vibrations, and can easily use the machine tool.

Abstract: A thread cutting machine for cutting a thread by rotating a main spindle and moving a feed axis includes a main-spindle speed computing section that computes and outputs a rotation speed of the main spindle based on a main-spindle rotation speed instruction for each thread cutting pass, and an acceleration/deceleration time computing section that computes and outputs an acceleration/deceleration delay time of the feed axis for each thread cutting pass so that a product of multiplication of the acceleration/deceleration delay time of the feed axis and the rotation speed of the main spindle is the same for all thread cutting passes.

Abstract: A method includes: (a) transferring a tool to where thread cutting is to start; (b) cutting threads in work with the tool; (c) performing tool deceleration along the Z-axis and acceleration along the X-axis during a predetermined acceleration/deceleration time Ta to retract the tool along the X-axis; and (d) returning the tool to a reference point. In Step (c), to shorten the incomplete thread portion, a command is issued concurrently with the start of the acceleration/deceleration time Ta to realize a pullout speed Ve along the X-axis that exceeds an allowable maximum speed Vmax to increase the acceleration along the X-axis. The speed command for moving the tool along the X-axis is maintained at the value of zero from the elapse of command time Te until the acceleration/deceleration time Ta expires to maintain the actual speed of the tool along the X-axis at or below the allowable maximum speed Vmax.

Abstract: The present invention provides a simple method of reducing an incomplete thread portion comprising the steps of: (a) transferring a tool in the direction of the X-axis to position the tool at the point where thread cutting is to be started; (b) transferring the tool in the direction of the Z-axis in synchronization with the rotation of the main spindle to cut threads in work; (c) performing a pullout operation by deceleration in the direction of the Z-axis and acceleration in the direction of the X-axis during a predetermined acceleration/deceleration time Ta so as to retract the tool in the direction of the X-axis; and (d) withdrawing the tool in the direction of the Z-axis to return the tool to the reference point of the thread cutting cycle.

Abstract: A thermosensitive recording sheet having a coated film containing a color-forming lactone compound, an acidic substance and a sensitizer. The sensitizer is at least one aliphatic carboxylic acid ester represented by the formula ##STR1## wherein R.sup.1 and R.sup.2 are identical or different and each represents an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group, a group of the formula --C.sub.n H.sub.2n --Ar in which n is an integer of 1 to 8 and Ar is an aryl group, or a group of the formula --C.sub.n H.sub.2n --CO--Ar in which n and Ar are as defined; R.sup.3 represents a group of the formula --C.sub.n H.sub.2n --in which n is as defined; R.sup.4 and R.sup.5 are identical or different and each represents an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, a group of the formula --C.sub.n H.sub.2n --Ar in which n and Ar are as defined, or a group of the formula --C.sub.n H.sub.2n --CO--Ar in which n and Ar are as defined; and R.sup.