JPH0359500B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an apparatus for processing a helical scan lead portion of a lower cylinder for a rotating head type magnetic recording/reproducing device with high precision.

Conventional technology The lead part of a helical scan is the most important part that guides the running of the magnetic tape, and processing the helical curve of the lead part with high precision has an extremely large effect on improving the quality of magnetic recording and playback. It is something that gives rise to

A conventional helical scan (hereinafter simply referred to as helical scan) lead part processing device for a lower cylinder for a rotary head type magnetic recording/reproducing device is a second
As shown in the figure, a chuck G that grips the lower cylinder C and a lead part processing cam plate P having a lead part guide cam surface F of the helical scan H are integrally fixed concentrically to the drive main shaft S, and the main shaft S is rotatably supported by a headstock M on the bed (not shown) of the lathe.

On the other hand, a cutter support A, which has a feeding means orthogonal to the main axis S and is supported by a tool stand (not shown) installed on a carriage on the bed, is attached to a chuck G.
The lower cylinder C is swingable in the generatrix direction of the lower cylinder C held by the lower cylinder C, and has means (not shown) that is biased in the direction of pressing against the cam surface F. Therefore, the cam roller R, which is pivotally supported by the cutter support A, is always pressed against the cam surface F, and when the cam plate P rotates, the cutter support A is reciprocated in the generatrix direction of the lower cylinder C in relation to the cam surface F. make it move.

The cutter support A is equipped with a cylinder that sends the cutter mount T on which the lead part processing cutter T ₁ and the lead outer diameter part processing cutter T ₂ are attached in the direction of the generatrix of the lower cylinder C with respect to the cutter support A. has been done.

When the main shaft S is rotated when machining the lead part of the helical scan H, since the lead part guiding cam surface F is inclined, the lead part processing cam plate P rotates unbalanced and a bending moment is applied to the main shaft S. As a result, lateral runout occurs in the main shaft S, which significantly reduces the machining accuracy of the lead curve of the helical scan H and the outer circumferential surface of the lead part.

Therefore, in conventional equipment, when turning the lead part and outer diameter part of the helical scan, the spindle S is rotated at a low speed of 200 to 500 rpm to prevent unbalanced turning in order to prevent such deterioration of machining accuracy. The moment due to this is minimized as much as possible.

On the other hand, when machining other reference surfaces, bearing holes, etc. that do not require high-precision machining other than the lead part and lead outer diameter part of the Helical Scan H, 2000 ~
The main shaft S rotates at a high speed of 3000 rpm.

Due to the difference in spindle rotation speed during machining,
A large difference occurs in the centrifugal force applied to the main shaft S,
Since the amount of lateral vibration of the main shaft changes greatly between low-speed rotation and high-speed rotation, not only is excessive fatigue applied to the main shaft S, but also the relationship between the reference surface of the lower cylinder C, the bearing hole, etc., and the lead outer shape It becomes extremely difficult to maintain concentric accuracy within ultra-high accuracy. Moreover, since the cam roller R of the blade support A is pressed against the lead guide cam surface F, the main shaft is deflected, resulting in a helical scan H that requires the highest processing accuracy for guiding the magnetic tape. This results in a large deviation in the machining accuracy of the lead curve and the outer peripheral surface of the lead.

Problems to be Solved by the Invention The present invention is designed to prevent the main shaft from rotating at high speed without separating the lead processing cam plate P, which rotates unbalanced, from the gripping chuck.
By removing the bending moment applied to the spindle, the lateral runout of the spindle is suppressed, and processing accuracy is maintained at the required ultra-high level.

Means for Solving the Problems The present invention provides a gripping chuck for a lower cylinder for a rotary head type magnetic recording/reproducing device, which is fixed to the end of a drive spindle that is rotatably supported on a headstock on a bed, A lead cam plate having a lead part machining cam plate having a lead part machining guide cam surface for helical scan of the cylinder and at least one lead outer diameter part machining cam plate having a lead outer diameter part machining guide cam surface is concentric with the main shaft. and is provided with a synchronizing pin that is rotatably attached to the headstock and engages and disengages the gripping chuck and lead cam plate, and when the synchronizing pin engages and disengages, the lead cam plate is integrally connected to the gripping chuck. Alternatively, the lead cam plate is separated from the gripping chuck so that only the gripping chuck rotates at high speed and the lead cam plate does not rotate.

Function When turning the lead part and outer diameter part of the helical scan, the lower cylinder is gripped by the gripping chuck at the end of the main shaft, and the lead cam plate and gripping chuck are engaged with the synchronizing pin to rotate the main shaft at low speed. When driving and turning other parts, the synchronizing pin is disengaged and separated, the lead cam plate and chuck are separated, and the main shaft is driven to rotate at high speed.

Therefore, when the lead cam plate rotates together with the gripping chuck, the main shaft rotates at a low speed, so
The bending moment and lateral vibration to the main shaft caused by the rotation of the unbalanced lead cam plate are suppressed, and the turning process of the lead curve and the outer peripheral surface of the lead part can be carried out without reducing the machining accuracy. When the lead cam plate is separated from the gripping chuck and the main shaft rotates at high speed, no bending moment or pulsating abnormal load due to lateral vibration, etc., is generated on the main shaft by the lead cam plate, and therefore turning of parts other than the lead part is not possible. To greatly reduce turning time without reducing accuracy.

Embodiment FIG. 1 shows an embodiment of the present invention, in which a main spindle 2 is rotatably supported on a headstock 1.
A chuck 3 for gripping a lower cylinder (not shown) is fixed to one end of the main shaft 2, and a drive pulley 4 is fixed to the other end.

The lead cam plate 5 has a cylindrical bearing part 6, and the bearing part 6 is rotatably mounted in an annular groove 7 formed concentrically with the main spindle 2 and surrounding the main spindle bearing part in the end face of the headstock 1. has been done. Therefore, the lead cam plate rotates on the concentric circle of the main shaft 2.

Note that numerals 8 and 9 are both seal plates of the bearing portion.

The synchronizing pin 10 that connects the gripping chuck 3 and the lead cam plate 5 together or separates them from each other has a synchronizing pin engagement hole 11, which is recessed in a part of the opposing peripheral surface of the gripping chuck 3 and the lead cam plate 5, respectively. 12 (hole 12 in the figure) so that it can freely move forward and backward in the radial direction. The forward and backward movement of the synchronizing pin 10 is performed by controlling the supply and discharge of pressure fluid supplied to the one hole.

Therefore, when the synchronizing pin 10 is retracted and held in one of the holes by controlled fluid pressure, it is separated from the other hole (hole 11 in the figure), so that the driving rotation of the main shaft 2 is Since the lead cam plate 5 is not transmitted and only the gripping chuck 3 rotates and the lead cam plate 5 is not rotated, even if the main shaft 2 rotates at high speed, no bending moment is applied to the main shaft 2 and no lateral vibration occurs. , there is no risk of reducing the accuracy of the turning process, and rapid turning process can be performed, and when the synchronizing pin 10 is moved forward from the one hole by fluid pressure and inserted into the other hole. , since the rotational driving force of the main shaft 2 is transmitted to the lead cam plate 5 via the synchronizing pin 10,
Since the gripping chuck 3 and the lead cam plate 5 rotate integrally in synchronization with each other, in order to avoid the adverse effects of abnormal loads generated on the main shaft due to the rotation of the lead cam plate 5, the main shaft is rotated at a low speed for turning, and the main shaft 2 is turned at a low speed. This is to maintain high machining accuracy by suppressing the occurrence of abnormal loads that cause bending moments and lateral runout.

Effects of the Invention The present invention allows the gripping chuck fixed to the main shaft and the rotatable lead cam plate coaxially supported on the main shaft to be connected to each other by the engagement/disengagement/advancing/retracting operation of the synchronizing pin. The gripping chuck and the lead cam plate are integrated with each other, and the abnormal load on the main shaft caused by the rotation of the lead cam plate is suppressed by low-speed rotation, maintaining high machining accuracy. By separating the lead cam plate and cutting off the transmission of rotational driving force to the lead cam plate, only the gripping chuck is rotated at high speed, making it possible to perform turning at high speed while maintaining machining accuracy without creating an abnormal load on the main shaft. You can save time.

Furthermore, the lead cam plate is not directly attached to the main shaft, but is supported in an annular groove in the headstock that surrounds the bearing part of the main shaft, so the bearing bearing surface is significantly larger than the main shaft bearing bearing surface. Since it is possible to sufficiently prevent the above-mentioned adverse effect on the main shaft that occurs when the lead cam plate is rotated, this, together with the above-mentioned effects of low-speed rotation, enables ultra-high precision turning processing.

Moreover, while the lower cylinder is held in the gripping chuck, the lead part is turned at low speed and the parts other than the lead part are turned at high speed. The turning process is performed while maintaining concentric accuracy, and it brings about an excellent effect in ultra-high precision turning processing of the lower cylinder.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a headstock bearing a lower cylinder gripping chuck according to the present invention, and FIG. 2 is a vertical cross-sectional view of a main part of a conventional lower cylinder turning machine. 1... Headstock, 2... Spindle, 3... Gripping chuck, 5
...Lead cam plate, 10...Synchronization pin.

Claims (1)

[Claims] 1. A gripping chuck for a lower cylinder for a rotary head type magnetic recording/reproducing device is fixed to the end of a drive spindle rotatably supported by a headstock on a bed, and
A lead cam plate of the helical scan of the lower cylinder is attached concentrically to the main shaft and rotatably to the headstock, and a synchronizing pin is provided for mutually engaging and disengaging the gripping chuck and the lead cam plate, and when the synchronizing pin is engaged, A helical scan processing device for a lower cylinder of a rotary head type magnetic recording/reproducing device, in which a lead cam plate is integrally formed with a gripping chuck and is rotationally driven by the main shaft, and when a synchronizing pin is detached, only the gripping chuck is rotationally driven by the main shaft. .