JPH0369642B2 - - Google Patents

Description

[Detailed description of the invention] (Purpose of the invention) Industrial application field This application grasps the workpiece with a jyo (both master and top jyo are collectively referred to as jyo), and cuts it while rotating at high speed. Compensates for the gripping force that tends to decrease due to the centrifugal force that acts on the chuck during high-speed rotation, and
This prevents the gripping force from decreasing and also prevents the gripping force from increasing when the rotation is stopped.
As is well known, a chuck has a plurality of jaws attached to the chuck body and is rotated at high speed, so the stopping positions of the jaws are random and inconsistent. Therefore, in the entire text of this specification, when directions such as up and down or left and right are designated, the reference is the position P in FIG. 1, which will be described in detail later.

Prior Art It is widely known that when the chuck is rotated at high speed, the gripping force is reduced due to centrifugal force acting on the jaw. For example, for a wedge-shaped chuck with an outer diameter of 160 mm, commonly known as a 6-inch chuck, we actually measured the decrease in gripping force as the rotation increased, and found that the gripping force exceeded 2000 rotations/min as shown by the curve a in Figures 6 and 7. At high rotation speeds of 4000 rpm or higher, the gripping force decreases to such an extent that the ability to properly hold the workpiece being machined is compromised.

In order to deal with the centrifugal force acting on the jyo in this way, many solutions have been proposed in the past.
These can be roughly divided into the following types according to their operating type: rear weight type, side weight type, and crank weight type. There are No. 2657068 and No. 4047723, and the next second group is
45176, U.S. Pat. No. 2828134, U.S. Pat.
118181 (U.S. Patent No. 3984114), U.S. Patent No.
There is number 3370859. However, although all of the above-mentioned conventional devices have different operating methods, they all reduce the centrifugal force of the counterbalanced weight mounted inside the chuck body by the amount that the jyo escapes in the radial direction due to the centrifugal force acting on the jyo. The reaction force pushes the Jiyo back towards the axis, creating a balance and canceling out the centrifugal force acting on the Jiyo.

Considering the decrease in gripping force due to the centrifugal force acting on the chuck's jaw, when centrifugal force is applied to the jaw due to the rotation of the chuck, the master jaw's fitting part that fits into the master jaw's mounting groove on the chuck body is The moment that rotates the jyo in the direction of arrow M around the center, that is, 0 in Fig. 5, acts, causing the tip of the jyo to float, usually resulting in a "floating phenomenon."
This causes an elastic deformation called ``elastic deformation,'' and the gripping force decreases by that amount. This floating phenomenon occurs within the range of elastic deformation of the jaw, so when the rotation is stopped, the grip returns to its original gripping force. However, in the above-mentioned conventional balance chuck in which the reaction force due to the centrifugal force of the balance weight is applied in the axial direction, the chuck body side as shown in Fig. 5 is Because it is being pushed back in the axial direction as shown by arrow A, Jiyo remains in the above-mentioned floating phenomenon, but rather promotes the floating phenomenon and pushes Jiyo back in the axial direction, adding an equilibrium weight to the initial gripping force. The gripping force is compensated by increasing the tightening by the reaction force of the weight to offset the centrifugal force acting on the jaw. For this reason, when the rotation is stopped, only the gripping force corresponding to the decrease in gripping force due to the floating phenomenon of the Jiyo returns to the previous level, and the final gripping force when the rotation is stopped is equal to the initial gripping force at the beginning of gripping. The gripping force increases by the amount compensated for by the reaction force of the weight. Incidentally, the inventor discovered that a 6-inch wedge-type balance chuck with a rear weight type (a chuck based on U.S. Pat. No. 4,047,723) showed a decrease in gripping force as the rotation increased, and an end point when the rotation stopped. As a result of actually measuring the gripping force, the gripping force decreases as shown in curve b in FIG. 7 and returns as shown in curve c, and the final gripping force is approximately 50% higher than the initial gripping force. Furthermore, as a result of the inventor's actual measurements on various balance chucks currently in practical use in Japan, although the gripping force and rotational speed curve shown in Figure 7 changes depending on the type of chuck and the weight of the balance weight, the final gripping force is the initial gripping force of 1.4~
Most of them are 1.9 times larger, and are crank weight type balance chucks that increase the weight of the balance weight and increase the gripping force as the rotation increases (a chuck that implements U.S. Patent No. 3,370,859). ), the final gripping force is sometimes more than twice the initial gripping force.

In this way, conventional balance chucks clamp the workpiece with a strong gripping force after cutting the workpiece, which causes the workpiece to deform after machining, so it is suitable for workpieces that require precision or thin walls. The chuck that holds it has a drawback that makes it unusable. In particular, light alloy castings such as die casting, copper, and aluminum require high-speed rotation, but their use is restricted due to deformation after processing. If the initial gripping force when gripping the workpiece is reduced in consideration of this post-machining deformation, the gripping force during rotation will naturally become smaller, making heavy cutting impossible. Conventional balance chucks, therefore, e.g.
It has been used only for workpieces where deformation after machining is not a problem, such as bars or rough machining, or workpieces where deformation due to the final gripping force when rotation is stopped is not a problem, and its applications have been limited.

Therefore, in order to solve the problems of the conventional balance check, as shown in Japanese Patent Publication No. 58-58163 (Japanese Patent Application Laid-Open No. 1982-139809) and Japanese Patent Application Laid-open No. 114304-1987, The structure is such that the centrifugal force of the balance weight, which compensates for the gripping force of the jyo that tends to decrease due to the centrifugal force acting on the jyo, acts on the back surface near the outer periphery of the master jyo and pushes the master jyo forward. In addition, it is configured to act on the center end of the chuck of the master jaw to pull the master jaw backward, and guarantees the gripping force that tends to decrease due to the centrifugal force acting on the jaw during rotation. A device has been proposed that prevents the gripping force from decreasing and returns to the initial gripping force when rotation is stopped, thereby preventing deformation of the workpiece.

However, in the chuck shown in the above-mentioned Japanese Patent Publication No. 58-58163, a hole is provided in the balance weight in a direction perpendicular to the axis of rotation of the chuck, and a weight support pin is inserted into the hole. Therefore, it is necessary to increase the length of the balance weight in the front and back direction for the pivot support, which is difficult to implement for chuck bodies with small front and rear dimensions, and the centrifugal force acting on the balance weight must be increased If this was attempted, the rigidity of the chuck body would be greatly reduced, creating a problem that could not be implemented in small chucks. Furthermore, in the case of the chuck shown in JP-A No. 57-114304, the center end of the chuck of the master jaw is pulled rearward, so there is a large protrusion on the back of the master jaw. As a result, the chuck main body is required to have a large space to accommodate the protruding portion, and the rigidity of the chuck main body is reduced, resulting in a problem that it is difficult to implement in a small chuck.

This invention solves the above-mentioned problems with the conventional device and can be easily implemented even in small chucks.The master yaw is slidably mounted in a radial mounting groove on the front surface of the chuck main body. Attach the Top Jiyo to the front of the Master Jiyo,
In the chuck that slides the master jaw and moves the top jaw in the radial direction by the operation of a fluid pressure cylinder, the chuck body has a main weight storage chamber extending rearward from the outer peripheral end of each of the mounting grooves. A weight storage chamber consisting of a support leg storage chamber extending from the front end of the main weight storage chamber toward the center of the chuck is provided, and the weight storage chamber includes the main weight stored in the main weight storage chamber and the A balance weight consisting of a main leg extending from the front end of the main weight toward the center of the chuck and housed in the main weight storage chamber is attached, and the back surface of the master jyo is mounted on the front of the main weight of the balance weight. A support recess is provided on either the back surface of the support leg of the balance weight and the opposing surface of the chuck body facing the back surface, and the other surface is engaged with the support recess. The present invention is characterized by the provision of a weight support pin that can tiltably support the support leg.

Embodiment FIGS. 1 to 3 show an embodiment of the present application, and the basic structure of the chuck 1 described below is all the same as the conventional one, and since it is not the gist of the present application, only a rough explanation will be given and details will be omitted.

On the front surface of the chuck body 1a, there are a plurality of (three in the drawing) mounting grooves 3 for the master jaw 2 arranged radially.
are cut into the mounting grooves 3, and a master jaw 2 is slidably inserted into each of the mounting grooves 3. A notch 5 for positioning is provided on the front surface of the master jaw 2. After fitting a positioning protrusion 6 provided on the back of the top jaw 4 into the notch 5 for positioning, the top jaw 4 is secured with a bolt 7. 4 is fixed to the master jaw 2 to form a jaw 8, and the master jaw 2 has a T on the inner end in the radial direction, that is, on the lower end surface.
A tapered protrusion 9 having a letter shape is formed.
10 is a wedge plunger, which is inserted into the hole 1 of the main body 1a.
A T-shaped tapered groove 10a is provided on the outer periphery of the groove 10a, which is slidably inserted into the groove 1 in the longitudinal direction. A drawbar (not shown) is screwed onto the rear end of the wedge plunger 10, and the drawbar is reciprocated by a cylinder operated by fluid pressure, thereby causing the jaw 8 to slide up and down in the radial direction of the chuck body 1a. , grip and release the workpiece.

In the wedge-type chuck as described above, the gripping force compensation device 100 of the present application is as follows. Reference numeral 12 in the figure is a weight storage chamber, and the storage chamber 12 is connected to the mounting groove 3 of the master jogger from the back side of the chuck body 1a.
A main weight storage chamber 13 corresponding to and communicating with the main weight storage chamber 13, which is cut out in the outer peripheral portion 1b of the main body 1a;
As shown in FIG. 3, the main weight storage chamber 13 is composed of a support leg storage chamber 14 that hangs down in the radial direction from approximately the center of the front end of the main weight storage chamber 13 and communicates with the mounting groove 3 only on the front side. The front shape of the chamber 12 shown in FIG.
The crescent-shaped main weight storage chamber 13 and the supporting leg storage chamber 14 hanging down form an umbrella shape, and the side surface shown in FIG. is made as small as possible, yet the most effective compensation effect can be obtained.

Next, the balance weight 15 is as follows. Since the balance weight 15 is stored in the weight storage chamber 12, it naturally has an umbrella shape corresponding to the weight storage chamber 15. That is, 16 is a main weight part, which has a crescent shape with an arcuate upper surface and a flat lower surface, and an abutment part 16a is provided at the center of the front side as close to the arcuate surface as possible. Next, reference numeral 17 denotes a support leg, which is vertically disposed at the center of the front side of the main weight part 16 and at a position offset to the front side, and has an abutment part 17a at the lower end of the front side, similar to the main weight part 16. A spherical support recess 18, which is an example of a support recess, is provided near the lower end of the back side, and the dimensions of each part of the balanced weight 15 configured as described above are set as follows. . The radius of the arc-shaped portion on the upper surface of the main weight portion 16 is made slightly smaller than the radius of the chuck body 1a, and the diameters of both are equal at the maximum. The length of the main weight part 16 and the supporting leg part 17 from the front side to the back side (Fig. 2) is the length of the main weight storage chamber 13.
and the length of the support leg storage chamber 14 in the same direction,
The vertical length of the support leg 17 is set so that when the balance weight 15 is stored in the weight storage chamber 12, a gap 14a is created between the lower end of the support leg 17 and the support leg storage chamber 14, as shown in the drawing. Set to . Finally, the width of the front side of the support leg portion 17 is made as close as possible to the width of the support leg storage chamber 14 in order to eliminate rattling in the left and right direction in FIG.

Reference numeral 19 denotes an auxiliary weight with a spherical top, and in FIG.
It is housed so that it can be moved up and down via the . As described above, the balance weight 15 stores the supporting leg part 17 in the supporting leg storage chamber 14 and places the lower side of the main weight part 16 on the top of the auxiliary weight 19 in the weight storage chamber 12. It will be stored. 22 is a weight support pin,
The tip is a spherical support part 22a having a size that fits the support recess 18 bored on the back side of the support leg part 17, and is inserted into the support leg storage chamber 14 of the weight storage chamber 12 from the back side of the chuck main body 1a. Screw together toward
The supporting portion 22a at the tip is inserted into the supporting recess 18 of the supporting leg portion 17.
By fitting into the supporting leg portion 17, the supporting leg portion 17 is held in a joint-like sliding state without directionality, just like a universal joint. 23 is a cover plate attached to the back side of the chuck main body 1a, and covers the weight storage chamber 12 which is open to the back surface and the outer peripheral surface 1b of the main body 1a,
The inner circumferential surface 23a on the back side is slightly cut so as not to interfere with the rotation of the balance weight 15. When the balance weight 15 is stored in the weight storage chamber 12 as described above, the contact portion 16a provided on the front surface of the main weight portion 16 is attached to the support leg portion 17 near the outer peripheral end on the back side of the master body 2. The contact portion 17a also contacts the back side of the master jaw 2, and the balance weight 1
5 is elastically supported by the auxiliary weight 19 by the above two points and the elasticity of the elastic pad 21, and does not wobble within the weight storage chamber 12. Moreover, since the balance weight 15 is set to the above-mentioned related dimensions, when it is stored in the weight storage chamber 12 as described above, the main weight portion 16
Gaps 13a and 14a are created between the upper surface and the back side and the cover plate 23, and between the lower end and the back side of the support leg part 17 and the support leg storage chamber 14, respectively, to prevent rotation of the balance weight 15 due to centrifugal force. It is possible.

By the operation of a hydraulic cylinder (not shown), the jaws 8 move radially inward to grip the workpiece as in the conventional case. When the chuck rotates in this state, a moment M as shown in FIG. 5 acts due to the centrifugal force acting on the jaw 8, preventing the jaw 8 from rotating counterclockwise in FIG.
A so-called floating phenomenon occurs in which the lower end of the jaw 8 (the gripping surface of the workpiece) rises, and the gripping force decreases, and this becomes more noticeable as the rotational speed increases. However, in the present application, when the chuck rotates, centrifugal force naturally acts on both the balance weight 15 and the auxiliary weight 19, causing the balance weight 15 to rotate clockwise in FIG. 2 about the supporting leg support pin 22. The moment when the auxiliary weight 19 tries to push up the main weight part 16 acts, and the back side of the jog 8 is pressed by the moment B (FIG. 5). In other words, the above phenomenon is caused by the balance weight 15
and moment B of centrifugal force acting on auxiliary weight 19
acts on the moment M acting on the jaw 8 in the cutting direction, prevents the floating phenomenon of the jaw 8, and compensates for the decrease in gripping force due to high-speed rotation, so the gripping force of the jaw 8 is reduced during machining. Defects such as extremely low values are excluded.

Next, when the rotation of the chuck is stopped, the centrifugal force will no longer act on the jaw 8, so the gripping force of the jaw 8 will return to the initial gripping force used to grip the workpiece, and of course the balance weight 15 and the auxiliary weight 19 will be Since the moment B caused by the rotation is also eliminated, unlike the conventional device which compensates for the gripping force by pushing down the jaw 8 in the direction A in Fig. 5, even if the rotation is stopped, the moment pushing the jaw 8 from the direction A remains. This eliminates the drawbacks of the conventional method in which the gripping force increases by adding the gripping force due to the residual moment to the initial gripping force, and the gripped workpiece does not deform after processing.

The applicant actually measured the decrease in gripping force with rotation and the final gripping force when rotation was stopped using a 6-inch chuck in which the above embodiment of the present application was implemented, and the results were as follows:
As the gripping force is rotated at high speed, the gripping force slightly decreases as shown in the curve d in Fig. 6, but it does not drop as rapidly as the curve a in the case of a chuck that does not compensate for the gripping force, and the jaw 8 is The same compensation effect as a conventional balance chuck that is pushed down in the direction can be obtained. On the other hand, if the rotation speed is decreased, the gripping force e
The curve returned to its original state along the above d curve, and it was confirmed that the final gripping force when the rotation stopped was equal to the initial gripping force, and was compensated by a balance weight like a conventional balance chuck. The gripping force remains and the final gripping force does not increase abnormally.

In the embodiment of the present application described above, the balance weight 15
Auxiliary weight 1 whose shape is umbrella-shaped and provided separately from this
9 assists centrifugal force, but the implementation of the present application is not limited to this. That is, the same compensation effect can be obtained even if the auxiliary weight 19 is vertically provided on the lower surface of the main weight part 16 integrally with the main weight part 16 to increase the weight of the balance weight 15. The diameter of the storage chamber 20 is made larger than shown in the figure, and the auxiliary weight 19 can be rotated within the storage chamber 20. Furthermore, in the above-mentioned embodiment using the umbrella-shaped counterweight 15 and the auxiliary weight 19, the chuck is relatively small, and the provision of the large weight storage chamber 12 may reduce the rigidity of the chuck body. This is particularly effective in cases where the chuck is large and there is no need to worry about a decrease in rigidity. The object of the present invention can be achieved even with a block shape having an arbitrary shape without being limited to the shape. In short, the shape of the balance weight 15 does not matter as long as it rotates due to the centrifugal force caused by the rotation of the chuck and pushes the back side of the jaw 8 to compensate for the decreased gripping force. In the above embodiment, the balance weight 15 is supported by the weight support pin 22, but instead of supporting the support pin 22, a protrusion corresponding to the support part 22a is provided on the support leg 17 of the balance weight 15. The balance weight 15 may be supported by providing a recess corresponding to the support recess 18 on the front side of the support leg storage chamber 14 (the reverse is also possible).

Finally, FIG. 4 shows another embodiment of the method for supporting the balance weight 15, in which a support hole 18a, which is exemplified as a support recess, is formed in the support leg 17 and passes through it back and forth, and the tip of the support pin 22 is supported on the other hand. A spherical support portion 22b having a diameter matching the hole 18a is formed, and by fitting this support portion 22b into the support hole 18a, the balance weight 15 is supported in a sliding state.

Effects As detailed above, in the present application, the balance weight is smoothly supported by the support pin driven from the back side of the chuck body, so that the rotation of the balance weight due to centrifugal force is extremely smooth. This not only compensates for the gripping force of the jaw that is about to decrease after achieving the desired purpose, but also prevents the final gripping force from increasing. Unlike the case where a balanced weight is supported on the horizontal axis in the left-right direction, the supporting part can be made smaller, and it can be applied to both large and small chucks without reducing the rigidity of the main body. It is also a useful invention that can be used for hand-tightening chucks that do not use fluid pressure.

[Brief explanation of drawings]

The drawings show the embodiment of the present application, and FIG. 1 is a front view, FIG. 2 is a sectional view taken along the line A-A in FIG. Figure, 4th
The figure is a sectional view of another embodiment, FIG. 5 is a diagram explaining the principle,
FIG. 6 is a diagram showing changes in the gripping force of a 6-inch chuck according to the present invention, and FIG. 7 is a diagram showing changes in gripping force of a conventional 6-inch chuck. 1...chuck, 1a...chuck body, 3...
... Mounting groove, 8... Jiyo, 12... Weight storage chamber,
15... Balance weight, 16... Main weight part, 17... Support leg part, 18... Support recess, 18a... Support hole, 1
9... Auxiliary weight, 22... Weight support pin, 22,
22a...Supporting part.

Claims (1)

[Claims] 1. A master jaw is slidably mounted in a radial mounting groove on the front surface of the chuck main body, a top jaw is attached to the front face of the master jaw, and the master jaw is slid by the operation of a fluid pressure cylinder. In a chuck that moves the top and yaw in the radial direction, the chuck body has a main weight storage chamber extending rearward from the outer peripheral end of each of the mounting grooves and a main weight storage chamber extending from the front end of the main weight storage chamber toward the center of the chuck. A weight storage chamber consisting of an extending support leg storage chamber is provided, and the weight storage chamber includes a main weight section stored in the main weight storage chamber and a main weight section extending from the front end of the main weight section toward the center of the chuck. A balance weight consisting of a support leg housed in the support leg storage chamber is installed, and a contact part that can come into contact with the back surface of the master jyo is provided on the front side of the main weight of the balance weight, and the balance weight is A support recess is provided on either the back surface of the support leg and the opposing surface of the chuck body facing the back surface, and a weight support pin that engages with the support recess and can tiltably support the support leg on the other side. A balance chuck consisting of a 2. Install the master jaw in a radial direction mounting groove on the front of the chuck body so that it can slide freely, attach the top jaw to the front of the master jaw, and slide the master jaw by the operation of the fluid pressure cylinder to adjust the top jaw to the radius. In the chuck to be moved in the direction, the chuck main body has a wide main weight storage chamber extending rearward from the outer circumferential end of each of the mounting grooves, and a wide main weight storage chamber extending from the center of the front end of the main weight storage chamber toward the center of the chuck. A weight storage chamber consisting of a narrow support leg storage chamber is provided, and the weight storage chamber includes a main weight section stored in the main weight storage chamber and a main weight section extending from the front end of the main weight section toward the center of the chuck. A balance weight consisting of a support leg housed in the support leg storage chamber is installed, and a contact part that can come into contact with the back surface of the master jyo is provided on the front side of the main weight of the balance weight, and the balance weight is A support recess is provided on either the back surface of the support leg and the opposing surface of the chuck body facing the back surface, and a weight support pin that engages with the support recess and can tiltably support the support leg on the other side. The chuck body is further provided with radial storage chambers opening into the main weight storage chambers on both sides of the rear part of the support leg, and auxiliary weights facing the inner surface of the main weight are provided in these storage chambers. A balance chuck that is fitted in such a way that it can move freely.