JPH03175B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention primarily relates to a tool holder for holding a tap.

(Prior art) Various types of tap holders equipped with safe torque (safety device) type clutch mechanisms have been developed, and these clutch mechanisms have a maximum clutch transmission torque value that depends on the size of the tap and the cutting torque. It is set. Further, the clutch mechanism of the conventional tap holder is designed so that the clutch can be disengaged in response to the occurrence of abnormal torque, both during forward rotation and reverse rotation. That is, in thread cutting work, after forward rotation (forward rotation) for thread cutting, it is necessary to rotate the tap in the opposite direction to remove it from the screw hole, but the clutch is designed to disengage if abnormal torque is generated during any rotation. In addition, there are some devices in which the set times for forward rotation and reverse rotation are slightly different.

By the way, as can be seen when considering the case of thread cutting a bottom hole, the clutch cutting action is utilized extremely effectively during forward rotation for thread cutting, but the situation in which the clutch cutting action is utilized during extraction rotation rarely occurs. There is a concern that the clutch may become disengaged unnecessarily, reducing the efficiency of the extraction operation.

In addition, as a conventional example, a tool holder whose clutch is activated only during forward rotation is
48331, which has an inclined notch for holding the ball on the driving member side and a clutch groove on the driven member side. Furthermore, since a cylindrical thrust ring is fitted into the annular hole as a member to hold down the clutch ball, the smooth movement of the thrust ring may be hindered due to the inclination of the thrust ring, or the holding force of the clutch ball may be uneven. I become familiar with it.

(Objective of the Invention) The object of the present invention is to secure stability by reliably stopping the rotation of the tap when abnormal torque occurs during forward rotation of the thread when performing thread cutting work, for example, and to ensure stability when the tap rotates forward. The object of the present invention is to improve work efficiency by making it possible to reliably and smoothly pull out a tap from a screw hole during rotation, and to further improve the holding strength of a clutch ball.

Another object of the present invention is to be able to press each clutch ball evenly with a simple presser member.
It is one.

(Technical Means for Achieving the Object) In order to achieve the above object, the present invention provides a clutch ball holding hole in the driven shaft 4 as a clutch mechanism.
6 are formed at intervals in the circumferential direction, a clutch ball 8 is inserted into the holding hole 16, a clutch groove 17 is formed in the drive ring 6, and the clutch ball 8 is inserted into the driven shaft 4. The presser ball 20 that abuts from the opposite side is fitted so as to be freely movable in the axial direction, and by urging the presser ball 20 with the clutch spring 9, the clutch ball 8 is pushed radially outward and engaged with the clutch groove 17 in a freely engageable and disengageable manner. The shape of the holding hole 16 is tilted outward in the radial direction so that the direction is opposite to the forward rotation direction of the tool, and when the torque during forward rotation is greater than the set value, the driven shaft 4 and the The drive ring 6 is moved against the held clutch ball 8.
rotates in the forward rotation direction while holding down the ball 8.

(Example) The present invention will be explained below based on the drawings.

In Figure 1, the tap holder is the holder main body 1.
(imaginary line) and tap collect 2,
A handle (not shown) on the rear end side (opposite the arrow F side) of the main body 1 is connected to a rotating main shaft of a machine tool. The tap collet 2 includes a driven shaft 4, a lock bolt 23, etc., and also incorporates a one-way rotating clutch mechanism consisting of a drive ring 6, a presser ball 20, a clutch ball 8, a clutch spring 9, etc.

The drive ring 6 has its backward protrusion 6a in the recess 1 of the main body 1.
a, so that it always rotates integrally with the main body 1, and the driven shaft 4 fits into the inner circumference of the drive ring 6, and receives torque from the drive ring 6 via the clutch ball 8, etc. is transmitted. A plurality of holding holes 16 for holding the clutch ball 8 are formed in the driven shaft 4 at intervals in the circumferential direction.
A clutch groove 17 is formed in the drive ring 6 and can be freely engaged with the clutch groove 17. The clutch spring 9 is compressed within the driven shaft 4 and is connected to the clutch ball 8 via the presser ball 20.
is pressed outward with constant pressure. Reference numeral 21 denotes a clutch spring adjusting nut, which is screwed into a female threaded portion on the inner circumference of the rear end of the driven shaft 4. The presser ball 20 is fitted into the driven shaft 4 so as to be movable in the axial direction. The lock bolt 23 tightens the tap T.

As shown in FIG. 2, the holding hole 16 is inclined so that as it goes inward in the radial direction, it is in the forward rotation A direction. In other words, it is inclined toward the direction of reverse rotation B toward the drive ring 6 side.

The set value of the clutch maximum transmission torque is determined by adjusting the amount of compression of the clutch spring 9 using the adjustment nut 21.
Taking into account that an inward force is applied to the clutch ball 8 due to the cam action of the clutch ball 8, the clutch spring 9 is adjusted and set to a value that can sufficiently secure the transmission torque required during forward rotation for thread cutting.

When threading a bottom hole, during forward rotation for thread cutting (rotation in the direction of arrow A), the elastic force of the clutch spring 9 maintains the clutch engaged state, that is, the engaged state of the clutch ball 8 and the clutch groove 17. It will be done.

When it reaches the bottom of the hole and a large load is applied to the tap T, the drive ring 6 twists in the direction of arrow A with respect to the driven shaft 4, causing the clutch ball 8 to move into the holding hole 1.
The cam action of 6 pushes the clutch inwardly along the retaining hole 16, disengaging the clutch.

When the extraction is rotated in the reverse direction (rotating in the direction of arrow B), the cam action of the holding hole 16 acts to push the ball 8 outward, so the clutch is always kept in the engaged state and the extraction operation can be performed reliably. I can do it.

(Effects of the Invention) As explained above, the present invention has the following advantages.

(1) Slanted clutch ball holding hole 1 on driven shaft 4
6, a clutch groove 17 for engaging the clutch ball 8 is formed in the drive ring 6, and a ball holding hole 16 into which the clutch ball 8 is inserted is formed in the drive ring 6.
By slanting the blade so that it becomes more radially outward, it is closer to the forward rotation direction and to the opposite direction, so that the cutting torque remains in the clutch engaged state within the set value during forward rotation, and becomes the clutch disengaged state when it exceeds the set value. Therefore, when attaching the tap T and threading the bottom hole,
By setting the forward rotation direction as the forward rotation direction for thread cutting, the clutch is reliably disengaged when reaching the bottom of the hole or when more torque is generated, and sufficient stability can be ensured.

(2) Moreover, since the holding hole 16 is tilted to prevent clutch disengagement during reverse rotation, there is no need to worry about the clutch being unnecessarily disengaged during extraction work due to reverse rotation, improving work efficiency.

(3) A clutch ball holding hole 16 is formed in the driven shaft 4 that fits on the inner circumferential side of the drive ring 6, and the clutch groove 1
7 is formed in the drive ring 6, compactness in the radial direction can be maintained compared to the case where the holding hole 16 is formed on the drive ring 6 side.

(4) Since the holding hole 16 into which the clutch ball 8 is inserted is a through hole, the holding strength of the clutch ball is higher than, for example, the conventional case where the clutch ball is inserted into a notch with an open end. There is little fear that the inner peripheral surface of the holding hole 16 that comes into contact with the clutch ball 8 will bend or deform.

That is, the holding hole 16 is a through hole whose inner peripheral surface is closed, and is not a notch with one end open. Therefore, the portion of the inner peripheral surface of the holding hole 16 that comes into contact with the clutch ball 8 is supported on both sides. For example, when a large load is applied to the driven shaft 4 when the bottom of a hole is reached during thread cutting work, the clutch ball 8 The strength of the part in contact with is high, and the possibility of bending or deforming is extremely small. Therefore, it has good durability.

(5) Slanted clutch ball holding hole 1 on driven shaft 4
6, and the drive ring 6 has a clutch groove 17 in which the ball 8 is removably fitted.The clutch ball 8 is always held on the driven shaft 4, and in the event of overload, the drive ring 6 and rotates with respect to the driven shaft 4. This makes it possible to provide a function to automatically notify the operator of the clutch disengaged state at the time of overload, and there is no need to provide a special abnormality warning device.

That is, if a load exceeding the set torque is applied during forward rotation, the ball 8 will come off the clutch groove 17 and the clutch will be in a disengaged state, but the sliding surface of the drive ring 6, for example, the inner circumferential surface of the drive ring in FIG. Since it rotates (idling) with respect to the ball 8 and the driven shaft 4 while contacting the ball 8, each time the clutch groove 17 passes the ball 8 portion, the ball 8 hits the clutch groove 17 due to the action of the spring 9, and a sound is generated. do. In other words, while the drive ring 6 is idling, a rattling sound is generated continuously, and this sound serves as a warning sound to alert the operator that the clutch is disengaged due to overload.
The operator can reliably confirm the abnormal condition and take appropriate action. Since it can perform such functions, it is suitable for general-purpose machines manually operated or NC automatic machines, for example.

(6) Presser ball 2 is movable in the axial direction within the driven shaft 4.
0 is fitted, and the presser balls 20 are urged by the clutch spring 9 to push each clutch ball 8 radially outward and engage the clutch groove 17, so the structure and assembly are simple. Presser ball 20
It is possible to ensure smooth back movement of the clutch balls 8, and to press the plurality of clutch balls 8 evenly outward at all times.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a tool holder to which the present invention is applied, and FIG. 2 is a cross-sectional view taken from FIG. 8...
Clutch ball, 9...clutch spring, 16...ball holding hole, 17...clutch groove, 20...presser ball.

Claims (1)

[Claims] 1 Fit the driven shaft 4 on the inner peripheral surface of the drive ring 6 connected to the rotational drive source, fix a cutting tool to the driven shaft 4, and connect the drive ring 6 and the driven shaft 4 via a clutch mechanism. In a tool holder that is connected by
A plurality of clutch balls 8 are formed at intervals in the circumferential direction, and a clutch ball 8 is inserted into the holding hole 16, a clutch groove 17 is formed in the drive ring 6, and a clutch ball 8 is formed inwardly in the driven shaft 4. The presser ball 20 that comes into contact with the clutch ball 20 is fitted so as to be axially movable, and the clutch spring 9 biases the presser ball 20 to push the clutch ball 8 radially outward and engage the clutch groove 17 in a detachable manner. , the shape of the holding hole 16 is inclined in the direction opposite to the forward rotation direction of the tool as it goes outward in the radial direction, and when the torque during forward rotation is greater than the set value, the driven shaft 4 and the holding hole 16 are The drive ring 6
A tool holder characterized in that the tool holder rotates in the forward rotation direction while holding the ball 8.