JPH01171724A - Tap holder - Google Patents

Abstract

PURPOSE:To completely pull a tap out of a workpiece at the time of reverse rotation and enable the optimum setting of a torque control value at the time of both normal and reverse rotations by making the pressure angle of the cam face on the inner periphery of a driving ring to a ball on a reverse-rotation cam side smaller than that on a normal-rotating cam side. CONSTITUTION:A driving ring 7 has a projection 8 which is fitted to a driving shift and a rotation torque is transmitted from the driving shaft to the driving ring via the projection. Further, cam grooves 9 as many as the outer-periphery side opening portions of the holes 5 of a driven shaft 1 are formed opposite to the opening portions on the inner periphery side of the driving ring. The cam groove 9 is formed with a normal-rotation cam face 9a and a reverse-rotation cam face 9b, and when a pressure angle between a line l1 drawn from a shaft center O to the normal-rotation cam face 9a and the tangent m1 of the cam face is defined as alpha1 while defining a pressure angle between a line l2 equally drawn to the reverse-rotation cam face 9b side and the tangent m2 of the cam face as alpha2, the cam faces are formed so as to be alpha1>alpha2. Hence, depending on the difference in pressure angle, the rotation torque control value at the time of reverse rotation gets larger than that at the time of normal rotation with a torque control value under a defined spring pressure.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a tap holder for holding a tap tool used for thread cutting. (Prior art) A tap holder that holds a tap tool and is used for thread cutting has an axially biased ball interposed between the driven shaft on which the tool is attached and the drive shaft, and Various devices have been devised that transmit the rotational torque from the drive shaft to the driven shaft and, when the driven shaft stops, cause the drive shaft to idle by a clutch action by a ball. For example, JP-A-60-1
The f'L7'fi device disclosed in Publication No. 3117 has a ball holding groove with a narrow groove width and a holding groove with a wide groove width formed on the drive shaft,
A ball is inserted into each retaining groove, and when an overload is applied to the forward rotating driven shaft and the driven shaft stops, the clutch will disengage without generating an impact, causing the drive shaft to idle and tap. This prevents the tool from breaking and allows for quick and smooth reversal. (Problems to be Solved by the Invention) However, in all conventional products, the torque setting value of the rotational torque control mechanism between the drive ring and the driven shaft can only be set constant during forward rotation and reverse rotation. Additionally, the torque control value is set during normal rotation to prevent the tap tool from breaking due to overload during thread cutting, so the set value is usually small for safety reasons. be. In addition, the torque control value during forward rotation is also the torque control value during reverse rotation, so if the tap cutting edge bites chips remaining in the completed hole during reverse rotation to remove the tap tool, the rotation will be reduced. When the torque mechanism is activated, the driven shaft stops rotating and is pulled toward the drive shaft, so that the tapping tool may come off the driven shaft and be left behind on the workpiece. Particularly when machining centers and milling machines use machines to machine multiple threads on one workpiece, or even when threading is done in one place, several workpieces must be machined at the same time. If this is not done, the workpiece will proceed to the next process with the screws left unfinished, and this process will eventually become an unfinished part. In such cases, the screws must be manually added using a tapping tool, which poses a serious problem in terms of work. Furthermore, even if a person is directly operating a machine such as a drilling press or tapping machine, if the tapping tool comes off, the machine must be stopped, the tapping tool must be removed from the workpiece, and the tool must be reinstalled in the machine and threaded. It will not happen. Furthermore, if the torque control value is increased to deal with these problems, a problem arises in that the tap tool becomes more likely to break. (Means for solving the problem) The present invention aims to solve the above problems. , a tool is attached to the tip, and the rear end has a driven shaft that removably engages with the drive shaft, and a driven shaft that is coaxially inserted into the outer circumferential side of the driven shaft and engages with the octagonal driving shaft to rotate together with the drive shaft. and a drive ring that transmits rotational torque to the shaft, and the driven shaft and the drive ring are positioned so that they can rotate relative to each other and cannot move in the axial direction, and the driven shaft has a center hole and a Drill a hole opening into the center hole, insert a pole into the hole, insert a spring member and a holding member into the center hole, and press the pole through the holding member to the outer periphery of the driven shaft. a cam groove is formed in the drive ring corresponding to the opening on the outer peripheral side of the hole of the driven shaft, and the pawl is pressed into contact with the cam groove;
A cam surface for forward rotation and a cam surface for reverse rotation are formed in the cam groove, and the pressure angle formed by the line 2+ drawn from the shaft center to the cam surface for forward rotation and the tangent line of the cam is α1, from the thin line to the cam surface for reverse rotation. Subtracted m
When the pressure angle between t2 and the tangent to the cam is α2, α1
>α2 is due to the constant spring pressure due to the difference in pressure angle.The rotational torque is generated from the drive shaft (not shown) to the drive ring (7).
, pole α4, and driven shaft [1] in this order. Furthermore, the pole Q41 that transmits the rotational torque to the driven shaft is shown in Fig. 9 and Fig. 1.
As shown in figure O, the holding member α is pressed by the spring αQ.
radially outward force N from the conical surface (15a) of the drive ring (7), force F from the cam surface (9a) or (90) of the drive ring (7), and the hole (5) of the driven shaft (1). It is balanced by receiving the force P from the wall. (However, since centrifugal force and gravity are smaller than the previous three forces, they will be ignored at this time.) The cam groove (9) has a forward rotation cam (9a) and a reverse rotation cam (9a) as shown in Figure 8. Consists of cam (90) nl, line Z drawn from axis 0 to recam
1. The pressure angle between zt and the tangent to the cam is α1,
When α2 is assumed, α1>α2. As shown, N1 and N2 are the forces received from the pressing member α, and assuming that the force from the drive ring (7) is f Fl, F2 and the radius of the driven contact is 'jznI, n2, the difference between these forces is as follows. The following relationship holds true. P1ki Fl-008α11ki T1/nl・・・・・・
...(1) F2-cosα21ki T2/n in P2
2・・・・・・・・・・・・・・・(2) N l
Ki Fl-β1n α11 / ・・・ ・・・
・・・ ・・・ ・・・・・・ ・・・ (3) N2
KiF2・s1nα21 ・・・・・・・・・・・・
・・・・・・・・・(4)+11, N from (3)
l −cotα11 = Tl/n, °°...(5
)(2+, (4) yo ri N 2
” Cot α21 = T2/n2
・---(6) If the force required to push pole α4 into the shaft center is NMAX, then this N during forward rotation and reverse rotation
Create the maximum torque TIMAX, T2M
If AX is <5), from (6), NMAX = TIMAX/n, @ tanα11 =
T2MAX/n2 ・tanα21. By the way, NlkiN2 α11>α21,', tanαtt>tanα21,”, TIM
AX < T2MAX. T I MAX and T2 MAX are the maximum torques that can be transmitted during forward rotation and reverse rotation, and these are the torque control values themselves. Therefore, the torque control value for forward rotation (T IMAX ) is smaller than the torque control value for reverse rotation (T2MAI). (Example) To explain an example of the present invention with reference to the drawings, the driven shaft (1
) is provided with a tap holding hole (3) at its tip, and a ring-shaped groove (4) is formed at its rear end into which a ball (not shown) is incorporated, and which engages with a drive shaft (not shown) through the ball. However, a t-th annular groove (6) is formed in the intermediate portion to engage with the drive ring (7) via the ball (6). A center hole (2) for housing the spring α6e is formed along the central axis (X-X) of the driven shaft, and the hole further communicates with a square hole α for inserting the tank of a tap tool (not shown). are doing. Further, a hole (5) opening into the center hole (2) passes through the driven shaft (1), and a ball a4 is inserted into the hole (5). After completing the charging of each ball, a ball holding member ← which has a conical surface (15a) that comes into contact with the ball α→ is inserted into the center hole (2), and the ball is further passed through the pole holding member. Spring αQ1 that urges α4 radially outward
The spring receiving plate α is inserted into the center hole. On the other hand, the drive ring (7) is provided with a protrusion (8) that fits into the drive shaft (not shown), and rotational torque is transmitted from the drive shaft to the drive ring through the protrusion. is a driven shaft

The same number of cam grooves (9) as the openings are formed corresponding to the openings on the outer peripheral side of the holes (5) in [1]. As shown in Fig. 8, the cam groove (9) consists of a forward rotation cam surface (9a) and a reverse rotation cam surface (90). (11) (!: Pressure angle (αK) formed by the tangent line (ml) to the cam surface, and the line (t2) similarly drawn to the reversing cam (90) side and the tangent line (m2) to the cam surface. When the pressure angle formed by is (α2), false>α
The cam surface is formed so as to be 2. Further, a clear hole is formed on the inner circumference of the drive ring (7), and a screw hole συ is bored in the groove αO. Said driven shaft (1)
Insert the drive ring (7) concentrically around the outer circumference of the groove (6).
Align the position of the helical groove αO and fill the space formed between the two grooves from the screw hole aη with a large number of balls (6), and then screw the screw α3 into the screw hole to seal the pole α. Thus, as shown in Figure 1, the driven shaft (1) and the drive ring (
7) are combined through the ball a2' so that they are immovable in the axial direction and rotatable around the axis. (Effects) As described above, the present invention makes the pressure angle between the cam surface formed on the inner periphery of the drive ring and the ball smaller on the reverse rotation cam side than on the forward rotation cam side. This makes it possible to completely remove the tap tool from the workpiece during reverse rotation. Furthermore, by changing the pressure angle and spring pressure, the torque control value T'L can be set to the optimum value during normal rotation and reverse rotation, so that accurate tap setting can be performed. In addition, the number of parts is smaller than that of conventional products, and the structure is simple, so failures are less likely to occur and manufacturing is easier, making the overall product lighter and more compact.

[Brief explanation of the drawing]

Fig. 1 is a half-section front view of an embodiment of the present invention, and Figs. 2 to 4 are Fig. 1A showing the state of engagement of the ball with the cam groove.
5 is a sectional view of the driven shaft, FIG. 6 is a sectional view of the drive ring, FIG. 7 is a sectional view taken along FIG. 6 B-Bi, and FIG. 8 shows the main parts of the present invention. The explanatory diagrams shown in FIG. 9 and FIG. 1O are explanatory diagrams of the engagement state of the ball and the cam surface during normal rotation and reverse rotation. 1... Driven shaft 2... Center hole 5... Hole
7... Drive ring 9... Cam groove
14...Pole source 15...Pushing member 16...Spring agent Jun Kawauchi Engraving of 2 drawings (no changes in content) Former 1st compilation 2nd edition ¥) 3 Figure No. 5 Figure 6 '87 Diagram 8 Procedural amendment motion dismissed April 11, 1986

Claims (1)

[Claims] A tool is attached to the tip, and the rear end is fitted with a driven shaft that removably engages with the drive shaft, and is fitted coaxially to the outer circumference of the driven shaft, engages with the drive shaft, rotates together with the drive shaft, and becomes the driven shaft. and a drive ring that transmits rotational torque, the driven shaft and the drive ring are positioned so that they can rotate with respect to each other via balls and cannot move in the axial direction, and the driven shaft has a center hole and a A hole is drilled into the center hole, a ball is inserted into the hole, a spring member and a holding member are inserted into the center hole, and the ball is inserted into the outer peripheral side opening of the driven shaft through the holding member. Further, a cam groove is formed in the drive ring corresponding to the opening on the outer peripheral side of the hole of the driven shaft, and the ball is pressed against the cam groove, and a cam for forward rotation is formed in the cam groove. The pressure angle between the line l_1 drawn from the shaft center to the forward rotation cam surface and the tangent to the cam is α_1, and the pressure angle between the line l_2 drawn from the shaft center to the reverse rotation cam surface and the cam surface is α_1. A tap holder characterized in that α_1>α_2, where α_2 is the pressure angle formed with the tangent line.