JPH0123688Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a tool unclamping device for numerically controlled machine tools, such as machining centers. The present invention relates to a tool unclamping device that can reduce replacement time and reliably prevent fluctuation of a spindle drawbar during tool unclamping operation.

BACKGROUND TECHNOLOGY As is well known, numerically controlled machine tools such as machining centers are connected to a tool magazine or tool cassette through an automatic tool changer, and a tool selected according to a workpiece machining program is transferred to the numerically controlled machine tool. It is constructed so that it can be automatically exchanged between the main shaft of the machine and the tool pot of the tool magazine or tool cassette.

On the other hand, the spindle of a numerically controlled machine tool has a spindle drive motor for transmitting rotational driving force to the tool attached to the tip, and a tool unclamping hook attached to the drawbar fitted inside the spindle so that it can move forward and backward. A pressing device for transmitting aus is connected. In such power transmission systems, the main shaft and the main shaft drive motor are often indirectly connected via power transmission members such as belts or gears, and the unclamping force to the drawbar is When transmitting power, various problems arise due to the adoption of an indirect power transmission mechanism.

Problems to be Solved by the Invention To explain in more detail, when the main shaft and the main shaft drive motor are connected through an indirect power transmission mechanism such as the one described above, fluctuations in the main shaft rotational speed due to belt breakage or belt slipping occur. Problems such as the generation of noise due to gear meshing and the increase in the size of the spindle head due to the addition of a lubricating device occur, which impede reliable transmission of unclamping force and simplification of the structure of the spindle head. Furthermore, in many conventional tool unclamping devices, regardless of the spindle drive system, the unclamping force is directly transmitted to the spindle component other than the pull stud, such as the spindle bearing, which can cause damage to the bearing. Such inconveniences have been observed. On the other hand, in order to solve the various problems caused by the adoption of the above-mentioned indirect power transmission mechanism, an unclamping force generating device has also been provided in which a direct pressing type pull stud pressing cylinder is arranged on the axis of the main shaft. However, with this method, the operating position of the pressing member relative to the main shaft or drawbar often becomes unstable, and there is a risk that the load applied to the main shaft may fluctuate, causing fluctuations in the drawbar or main shaft.

In order to solve the above-mentioned inconvenience, a device was developed in 1983 that applied unclamping forces in opposite directions to the main shaft and drawbar using two levers.
Although disclosed in Publication No. 109436, this device
The midpoint of the two levers is pivoted to the main shaft head,
Since the structure is such that one end of each lever is engaged with the main shaft and the drawbar, in order to apply unclamping force to both levers, a driving force must be applied to the other end of both levers to cause them to expand to both sides. Not,
Therefore, a cylinder with a two-stage actuation structure is used, which has the drawback that the structure of the drive device is complicated and large.Moreover, the contact point between both levers and the main shaft and drawbar is centered around the pivot point of both levers. Therefore, if the surface accuracy of these pivot points is poor, there are drawbacks such as an incorrect load (bending force due to uneven contact) being generated on the main shaft.

The main object of the present invention is to provide a tool unclamping device having a simple structure and good operating characteristics, which can overcome the above-mentioned drawbacks of conventional devices.

Means for Solving the Problems In view of such an objective, the present invention has been developed by providing a spindle that is fitted and supported inside the spindle so as to be able to move forward and backward along the axial direction of the spindle, and is biased in the backward direction via a disc spring. a first pressure-receiving member fixed to the base end of a drawbar that clamps a tool attached to the tip of the spindle and exposed on the outer periphery of the spindle from a horizontal long hole in the spindle; one end serving as a restraining end; a first lever, the other end of which is a free end, and whose intermediate portion is arranged in close proximity to the surface of the first pressure-receiving member on the rear end side of the main shaft through a pressing member so as to be able to come into contact with and separate from the surface;
A second pressure receiving member is fixed on the outer periphery of the spindle at a position closer to the tip of the spindle than the first pressure receiving member, one end is a restrained end, the other end is a free end, and the intermediate portion is fixed to the outer circumference of the spindle at a position closer to the tip end of the main spindle. a second lever disposed close to the surface of the second pressure-receiving member on the tip side of the main shaft so as to be able to approach and separate;
The free ends of the first lever and the second lever are connected by a connecting rod substantially parallel to the main shaft, and the restrained end of one of the levers is rotatably supported on the main shaft head, while the other The restrained end of the clamp is connected to a drive device for generating unclamping force attached to the spindle head.

Operation When unclamping a tool, when the drive device moves the restraining end of one lever toward the restraining end of the other lever, the pressing member in the middle of the lever comes into contact with the corresponding pressure receiving member. The lever becomes a fulcrum, and the free end of the lever moves in the opposite direction, which is transmitted to the other lever via the connecting rod, and moves in the direction in which both pressure receiving members approach each other via the pressing member in the middle of both levers. Receives pressing force. As a result, the drawbar moves forward toward the tip of the spindle against the disc spring, releasing the tool clamp.

Embodiment FIG. 1 is a longitudinal cross-sectional view of the main spindle head of a machining center illustrating the overall structure of the device of the present invention, and FIG. 2 is an explanatory diagram of the operating sequence of the pressure receiving members by the link mechanism.

As shown in the figure, inside the main shaft 10 of the machining center, a drawbar 1 is moved forward and forward via a disc spring 5.
The main shaft 10 is fitted and supported so as to be freely retractable.
A rotating shaft 3 of a main shaft drive motor 2 is arranged concentrically on the axis of the main shaft.

The link mechanism L has a pin 17 connected to its drive device, for example, a piston rod 16 of a hydraulic cylinder mechanism 15.
a first lever 6 whose one end is rotatably connected to the other end of the first lever 6 through a pin 18; a connecting rod 4 whose one end is rotatably connected to the other end of the first lever 6 through a pin 18; a second lever 1 rotatably joined to the other end of the connecting rod 4 via a pin 20, and the other end rotatably joined to the spindle head 21 via a pin 20;
It is composed of 1. On the other hand, pressing members 7 and 12 are attached to the longitudinal center portions of the first lever 6 and the second lever 11 by appropriate fixing means such as screws. A first flange-shaped pressure receiving member 8 to which the unclamping force of the tool 9 is transmitted from the pressing member 7 of the first lever 6 is fixed to the base end of the drawbar 1. The unclamping force of the tool 9 is transmitted from the pressing member 12 of the second lever 11 to the base end of the main shaft 10 located on the mounting end side of the tool 9 when viewed from the first pressure receiving member 8. A second flange-shaped pressure receiving member 13 is fixed. The first flange-shaped pressure receiving member 8 and the second flange-shaped pressure receiving member 13
and are opposed to each other so that they are pressed toward each other by the forward stroke of the piston rod 16 of the hydraulic cylinder mechanism 15 when the link mechanism L is operated. As described above, the output end 24 of the first lever 6 and the input end 14 of the connecting rod 4 are connected to each other by the pin 18 so as to be relatively rotatable. A return spring 22 is arranged so as to maintain substantially the same axial direction as that of the connecting rod 4. The return spring 22 is provided to maintain a predetermined gap between the pressing member 12 of the second lever 11 and the second flange-shaped pressure receiving member 13 when the main shaft 10 is rotating. .
That is, when the main shaft 10 is rotating, there is no need to transmit the unclamping force to the drawbar 1, so the second lever 11 is moved toward the main shaft head 21 using the pressurizing restoring force of the return spring 22. A certain gap is left between the biasing and pressing member 12 and the pressure receiving member. For the same reason, when the main shaft 10 is rotating, the pressing member 7 of the first lever 6
A return spring 27 is provided between the hydraulic cylinder mechanism 15 and the first lever 6 in order to maintain a predetermined gap between the hydraulic cylinder mechanism 15 and the first flange-shaped pressure receiving member 8 . Further, at the input end 25 of the link mechanism L, that is, the input end of the first lever 6, the hydraulic cylinder mechanism, air cylinder mechanism, or linear movement mechanism such as a DC motor and a ball screw is connected as a source of unclamping force. A driving device 15 configured by a combination of the two is connected in series.

The operating procedure of the device of the present invention will be explained below. After the main shaft drive motor 2 stops rotating, pressure oil is introduced into the rear oil chamber of the hydraulic cylinder mechanism 15 to cause the piston rod 16 to make a forward stroke. Since the output end 24 of the first lever 6 is always urged toward the tool 9 side by the return spring 22, the pressing member 7 fixed to the longitudinal center of the first lever 6 At the initial stage of the unclamping operation when the first flange-like pressure-receiving member 8 starts to come into contact with the flange-like pressure-receiving member 8, no displacement occurs in the first flange-like pressure-receiving member 8 along the axial direction of the drawbar 1. When the forward stroke of the piston rod 16 further increases in this state, the connecting rod 4 rotates around the point of contact between the pressing member 7 and the first flange-shaped pressure receiving member 8 as shown by the arrow A in FIG.
An axial displacement occurs as shown by . Due to the displacement of the connecting rod 4 in the axial direction, the pressing member 12 of the second lever 11 and the second flange-shaped pressure receiving member 13 come into contact with each other, increasing the pressing force. When the pressing force exceeds the tensile force applied to the drawbar 1 by the disc spring 5, the unclamping force caused by the forward stroke of the piston rod 16 is caused by the first flange-shaped pressure receiving member 8 disposed oppositely. is urged toward the second flange-shaped pressure receiving member 13. At the end of this unclamping operation, as described above, the pressing member 12 of the second lever 11
The pressing force acting between the second flange-shaped pressure receiving member 13 and the second flange-shaped pressure receiving member 13 is larger than the tensile force applied to the drawbar 1 by the disc spring 5. Thus, as the piston rod 16 moves forward, the first flange-shaped pressure receiving member 8 fixed to the base end of the drawbar 1 is slid toward the tool 9 side.
In this way, when the relative sliding displacement amount of the first flange-shaped pressure receiving member 8 with respect to the main shaft 10 increases, the engagement state between the tool gripping pawl 26 fixed to the tip of the drawbar 1 and the tool 9 is released. Ru. The used tool 9 is thus held and removed from the tip of the spindle 10 by a tool attachment/detachment mechanism (not shown) provided on the arm of the automatic tool changer. Thereafter, a new tool 9 selected according to the workpiece pressurization program is fixed to the tip of the drawbar 1 through engagement with the tool gripping claw 23, and in this state, the piston rod 16 moves toward the backward stroke side. Can be switched. That is, the link mechanism L operates in the reverse order to the above order, and the drawbar 1
return to its original position.

Effects of the invention As can be understood from the above explanation, the tool unclamping device of the invention has two levers.
A floating link mechanism can be constructed by making one end of each end a restrained end and the other end a free end, and connecting them with a connecting rod. Since the tool unclamping device can be constructed by simply moving the tool, there is an advantage that a commercially available fluid pressure cylinder can be used as is as a driving means, and the entire structure can be made simple and inexpensive.

Of course, the unclamping force acting on the main shaft is canceled out, and since each fulcrum of the link is floating, there is a self-aligning effect on the pressure receiving part, and the unclamping force is applied on the axis of the main shaft. In order to achieve this, no improper or unreasonable force is applied to the spindle bearing, and when the tool is clamped, both levers and the connecting rod are completely separated from the spindle rotation system, thereby preventing any negative impact on the spindle load. It also has the effect of not giving.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a main spindle head of a machining center illustrating the overall structure of the device of the present invention, and FIG. 2 is an explanatory diagram of the order of operation of the pressure receiving member by the link mechanism. 1...Drawbar, 2...Spindle drive motor, 3
... Motor rotation shaft, 4 ... Connecting rod, 5 ... Disc spring, L ... Link mechanism, 6 ... First lever, 7 ... Pressing member, 8 ... First pressure receiving member, 9...Tool, 10...Main shaft, 11...Second lever, 12...Press member, 13...Second pressure receiving member, 15...Link mechanism drive device.

Claims (1)

[Scope of utility model registration request] It is fitted and supported inside the spindle so that it can move forward and backward along the axial direction of the spindle, and is biased in the backward direction via a disc spring and fixed to the base end of the drawbar that clamps the tool attached to the tip of the spindle. The first hole is exposed on the outer periphery of the main shaft through the long hole in the horizontal direction of the main shaft.
a first pressure-receiving member, one end of which is a restrained end, the other end of which is a free end, and an intermediate portion of the first pressure-receiving member is arranged close to and detachable from a surface on the rear end side of the main shaft via a pressing member. a lever, a second pressure receiving member fixed on the outer periphery of the spindle at a position closer to the tip of the spindle than the first pressure receiving member, one end of which is a restrained end, the other end is a free end, and an intermediate portion is pressed. and a second lever disposed in close proximity to the surface of the second pressure-receiving member on the tip side of the main shaft through a member, the free ends of the first lever and the second lever being substantially parallel to the main shaft. In addition, one of the restrained ends of both levers is rotatably supported on the spindle head, and the other restrained end is attached to the drive for generating unclamping force on the spindle head. A tool unclamp device for a numerically controlled machine tool, characterized in that it is connected to a device.