JPS6055243B2 - balance check - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a balance chuck that compensates for centrifugal force on jaws (top jaws fixed to a master jaw are collectively referred to as jaws) that grip a workpiece.

In order to reduce machining time and manufacturing costs, it is desirable to rotate the chuck at high speed, but when the chuck is rotated at high speed, the centrifugal force of the rotation acts on the jaws, reducing the gripping force.

Incidentally, the outer diameter is 16, which the inventor commonly calls the 6-inch chuck.
As a result of actually measuring the decrease in gripping force as the rotation speed increases for the wedge-type chuck No. 0771771, as shown in the curve a in Figure 9, the gripping force decreases rapidly when the speed exceeds 2000 rotations/minute, and when the rotation speed exceeds 4000 rotations/minute. At these high speeds, the gripping force of the chuck jaws is reduced to such an extent that the ability to properly hold the workpiece during machining is compromised. A number of solutions have been proposed in the past to deal with such centrifugal forces on the jaws of the chuck.

For example, Utility Model Application No. 52-119581, U.S. Patent No. 2729
45, as in the same No. 2657068 and the same No. 4047723, the balance 1-shape is slidably installed in the radial direction in the 1-spindle mounting groove on the rear side of the chuck body facing the master jaw, and the balance 1-shape and the master A balance chuck (rear single-spindle type) that connects the jaws with a leverage lever to offset centrifugal force, with a balance chuck on one or both sides of the master jaw, as in U.S. Pat. A balance chuck (one spindle type on the side) with one bow connected by a lever lever, JP-A-51-118181 (
U.S. Patent No. 3984114), U.S. Patent No. 33708
Balance chucks (crank 1 spindle type) and the like are provided, in which a balance chuck is attached to the crank lever that operates the master jaw, such as the 5 o'clock position. In all of these conventional balance chucks, the centrifugal force acting on the jaws causes the jaws to escape in the radial direction. Considering the reduction in gripping force due to centrifugal force acting on the jaws of the chuck, the jaws, which slide in the axial direction due to the operation of the fluid pressure cylinder, grip the workpiece. When centrifugal force due to rotation acts on the jaw, the jaw rotates in the direction of arrow M around the center of the fitting part of the master jaw that fits into the master jaw mounting groove of the chuck body, that is, 0 in Fig. 7. The tip of the jaw rises due to the floating moment, and normally 1
An elastic deformation called a floating phenomenon occurs, and the gripping force decreases accordingly. This floating phenomenon occurs within the range of elastic deformation of the jaws, so if the rotation is stopped, it will be 1E]! This will return to the initial grasping power that was grasped at the beginning. However, in the conventional balance chuck in which the reaction force of the balance weight is applied in the axial direction (direction of the rotation center of the chuck), the chuck body side is moved from the center of the fitting part of the master jaw (0 in Fig. 7) to the chuck body side as shown in Fig. 7. Because the jaw is pushed back in the axial direction as shown by arrow A, the jaw remains in the above-mentioned floating phenomenon.In fact, the jaw is pushed back in the axial direction in a way that promotes the floating phenomenon, and the grasping force that was initially grasped is increased. The gripping force is compensated by tightening the counterweight by the amount of the reaction force of the balance weight to offset the centrifugal force acting on the jaws. Therefore, when the rotation is stopped, only the gripping force corresponding to the decrease in gripping force due to the lifting phenomenon of the jaws returns to the previous level, and the final gripping force when the rotation is stopped is greater than 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 found that regarding a 6-inch wedge-type balance chuck with a rear weight type (a chuck implemented in U.S. Patent No. 4,047,723), the gripping force decreased as the rotation increased, and the terminal gripping force when the rotation stopped. As a result of actually measuring the force, the grasping force decreases as shown in curve b in FIG. 9, and returns as shown in curve c, and the final grasping force is about 50% higher than the initial grasping force. Furthermore, as a result of the inventor's actual measurements on various balance chucks currently in practical use in Japan, the curve of gripping force and rotation speed shown in Figure 9 changes depending on the type of chuck and the weight of the balance weight. The final grasping force is 1.4 to 1. A crank-weight type balance chuck, which is mostly manufactured by Kou, and which increases the weight of the balance weight and increases the gripping force as the rotation increases (a chuck that implements U.S. Patent No. 33708) In the bad method, there are cases where the final grasping force is more than twice the initial grasping force. In this way, conventional balance chucks use a powerful gripping force to tighten the workpiece after cutting the workpiece, which causes the workpiece to deform after machining, making it difficult to grasp workpieces that require precision or thin-walled workpieces. There are disadvantages that make it unusable.In particular, die casting, light alloy castings such as copper and aluminum require high speed rotation, but their use is restricted due to deformation after machining. If we take this post-machining deformation into account and reduce the initial gripping force when gripping the workpiece for the first time, the gripping force during rotation will naturally become smaller, making heavy cutting impossible. Therefore, conventional balance chucks are only useful for workpieces where deformation after machining is not a problem, such as bar stock or rough machining, or workpieces where deformation due to late gripping force when rotation is stopped is not a problem. The present invention solves this problem, and the cause of the increase in gripping force at the time of stopping rotation is that the compensating force due to the balanced weight is applied to the axis of the master jaw. Focusing on the fact that the centrifugal force acting on the jaw is applied to the master jaw, the centrifugal force compensation device is designed to compensate for the centrifugal force acting on the jaw. It is configured to act in a direction approximately perpendicular to the sliding direction of the master jaw to cancel the floating moment, and compensates for the centrifugal force of the jaw that grips the workpiece during rotation, and when rotation is stopped. It is characterized by returning to the initial gripping force and preventing deformation of the workpiece.The details will be explained below based on the embodiment shown in the drawings.

1 to 4 show an embodiment of a wedge-type chuck with a hollow chuck body. 1 is a cylindrical hollow chuck body, and on the front side (second right side), a radial master jaw is provided. Mounting grooves 2 (three in the illustrated example) are cut at equal angular intervals.

A third groove is provided on the opposite side of each of these mounting grooves 2.
As shown in the figure, guide grooves 2a, 2a are formed. A master jaw 3 is inserted into the mounting groove 2 so as to be slidable in the radial direction, and the master jaw 3 has the guide grooves 2a,
Protrusions 3a, 3a guided by 2a are provided, and the moment due to centrifugal force when the jaw rotates is received by these protrusions 3a, 3a and guide grooves 2a, 2a. A T-slot 3b is cut in the front side of the master jaw 3, and a jaw nut 6 is movably fitted into this T-slot 3b.
A saw blade-like serration 3c is formed on the front surface of the master jaw, and the selection 4a of the top jaw 4 is engaged with this, and the two bolts 7 are screwed into the jaw nuts 6 to connect the top jaw 4 to the master jaw. 3, the jaw 5 is configured. Further, at the radially inner end of the master jaw 3, a T-shaped taper portion 3d is formed as shown in FIG. A hollow wedge plunger 8 is fitted into the hole 1a of the main body 1 so as to be slidable in the axial direction,
A taper groove 8a having a T-shaped cross section is formed on its outer periphery and is slidably engaged with the T-shaped taper portion 3d. Female thread 8 cut into the hollow hole of the wedge plunger
A draw vibe 9 is screwed onto b, and the draw vibe 9 is caused to reciprocate in the axial direction by the operation of a pneumatic or vacuum type hydraulic cylinder (not shown). Main body 1
Behind the master jaw mounting groove 3 (left side in Figure 2)
, a weight mounting groove 1b that communicates with the mounting groove 2, and a weight storage chamber 1 that is continuous with the weight mounting groove 1b and bulges in the circumferential direction.
c is provided.

In the illustrated example, the weight storage chamber 1c is open on the rear side of the chuck body, and the back plate 11 is also formed with recesses for weight storage chambers 11a at three corresponding locations.
When attached with bolts 12, a storage chamber is formed. Reference numeral 10 denotes a balanced weight having an abutment portion 10a with an arc-shaped tip and a weight portion 10b.The portion into which the weight mounting groove 1b fits is formed with a rectangular cross section, and the balanced weight 10 is fitted into the groove 1b of the main body. The main body 1 and the weight part 1 are fitted into the body 1 and supported slidably in the radial direction by a weight support pin 13, so that the contact part 10a abuts the back surface part 3e near the outer periphery of the master jaw.
0b, and the centrifugal force applied to the balance weight 10 cancels the floating moment of the master jaw when grasping the workpiece against the master jaw 3. It acts in a direction substantially perpendicular to the sliding direction.

Note that the floating moment applied to the master jaw 3 is in a counterclockwise direction around the center of gravity 0, as shown in FIG. In the vicinity of the outer periphery of the master jaw 3, the back surface 3e is pushed in a direction substantially perpendicular to the sliding direction of the master jaw 3.
It is clear that near the inner periphery of the master jaw 3, the rear surface 3e of the master jaw 3 may be pulled to the left in FIG. 7 to cancel the floating moment. Since the balanced weight 10 is always in this state and does not displace, the weight part 10b accommodated in the weight storage chamber 1c requires only a small gap, and a stable centrifugal force can be obtained. Note that the spring 14 is always connected to the master jaw 3.
Although it is provided to bring the contact portion 10a of the balance weight 10 into contact with the back surface portion 3e of the balance weight 10, this may be omitted. Weight part 1
In order to improve the efficiency of centrifugal force acting on 0b, balance weight 1
0 is supported by a shaft 13 approximately parallel to the axis of the chuck body as shown in FIG. The centrifugal force of the balance weight 10 is increased by a factor of approximately S2 to push the back surface 3e of the master jaw 3 forward. In order to make the direction of this forward pushing force parallel to the axis of the chuck body 1 as much as possible, the master jaw back center portion 3f is recessed to bring the weight support pin 13 closer to the master jaw 3. 15 is weight support pin 1
3 is the set screw to prevent it from coming off, 16 is the chuck body 1
A fixing bolt 17 passing through the main body 1 and the back plate 11 is screwed into the spindle of the machine tool to fix the chuck.

When the draw vibe 9 is moved back and forth in the axial direction by the operation of a fluid pressure cylinder (not shown), the T-shaped taper groove 8a of the wedge plunger 8 and the T-shaped taper portion 3d of the master jaw 3 are engaged with each other. The master jaw 3 moves outward or inward in the radial direction due to the wedge action caused by the relative sliding of Understand or release information.

Even if the master jaw 3 moves in the radial direction, the balance weight 10 in contact with the back surface 3e of the master jaw remains in the state shown in FIG. 2 because the back surface 3e of the master jaw is a smooth surface. When the master jaw 3 moves inward and grasps the workpiece, it comes into contact with the back surface 3e near the outer periphery of the master jaw 3 by the distance moved from the state shown in FIG. When the chuck that grips the workpiece rotates, a lifting moment due to centrifugal force acts on the jaw 5, which is made up of the master jaw 3 and the top jaw 4, as shown in Figure 7, and the tip of the jaw 5 rises, so-called. Trying to cause Joe to levitate.
(The explanatory diagram in FIG. 7 shows a state in which the moment B of the balanced weight 10, which will be explained below, is not acting, that is, a state in which the jaw 5 is causing a floating phenomenon.) However, the balanced weight Since the centrifugal force due to rotation also acts on the weight part 10b of 10, the balance weight 10 moves to the second position with the weight support pin 13 as a fulcrum.
In the figure, the moment of rotation in the clockwise direction acts and doubles the centrifugal force of the weight, thereby increasing the back surface 3e of the top jaw 3.
Press. That is, the moment of centrifugal force acting on the balance weight 10 acts in a direction that cancels the moment of centrifugal force acting on the jaws 5, thereby preventing the jaw from floating and compensating for the decrease in gripping force caused by rotation. Ru. and joe 5
This means that the workpiece is grasped in the state in which it was initially grasped, preventing the floating phenomenon, so even if the rotation is stopped, it returns to the initial grasping force that was grasped at the beginning, and the workpiece will not deform after machining. I never wake up. As a result of manufacturing the 6-inch chuck of the above example and actually measuring the decrease in gripping force due to rotation and the final gripping force, the gripping force decreased slightly as shown in curve a in Figure 8, and was almost the same as curve d. It was confirmed that the final grasping force matched the initial grasping force as shown in the e-curve.

As is clear from the comparison between curve d in FIG. 8 and curve b in FIG. It turns out that you can get almost the same amount of compensation as Chuck. Figures 5 and 6 show an embodiment of a crank type chuck. As is known, in the crank type chuck, one end 22a of a bell crank 22 whose central portion is pivotally supported by a fixed shaft 21 attached to the chuck body 1 is engaged in a recess 23 formed on the back surface of the master jaw 3, and the other The end 22b is engaged in the recess 24a of the draw sleeve 24, and the draw sleeve 24 is connected to the drawper 26 with a bolt 25. When the draw sleeve 24 moves in the axial direction, the bell crank 22 is rotated and the master jaw 3 is adapted to be displaced radially inwardly or outwardly. If the bell crank 22 is built into the main body 1 on the rear side of the master jaw 3 in this way, it becomes difficult to pivotally support the balance weight as in the embodiments shown in FIGS. Therefore, master jaw mounting groove 2
Radial weight mounting grooves 27 are cut in the front surface of the back plate 11 on the rear side of the main body 1 facing each other at equal angular intervals, and the back plate 11 is fixed to the main body 1 with bolts. A balanced weight 28 whose front outer peripheral end is formed into a slanted slope 28a is inserted into this weight mounting groove 27 so as to be slidable in the radial direction. A pin hole 29 that communicates the master jaw mounting groove 2 and the weight mounting groove 27 of the main body 1 is bored near the outer periphery of the main body 1, and the slope 28 of the balance weight is formed.
A centrifugal force compensator is constructed by inserting a push pin 30 slidably in the axial direction so that both ends thereof are in contact with the rear surface 3e near the outer periphery of the master jaw. In this embodiment, a weight mounting groove 27 is provided on the front surface of the back plate 11 so that an existing crank-type chuck can be easily modified. It may be closed with a back plate 11. When such a balanced weight slider method is used, the push pin pushed by the centrifugal force of the balanced weight 28 acts parallel to the axis of the chuck body, that is, in a direction perpendicular to the sliding direction of the master jaw, causing the master jaw to float. It is preferable because it cancels the moment, and when you want to increase the force, use the slope 28a.
The force is increased by a wedge action by making the slope gentle. In addition, the balance weight 28 is prevented from flying out due to centrifugal force by simply engaging the push pin, and if it is not desirable for safety, a protrusion is integrally formed on the balance weight 28, and a safety groove is provided to prevent the balance weight 28 from flying out, into which the protrusion fits. may be formed on the main body 1 or the back plate 11. As described above, the centrifugal force compensator of the present invention causes the centrifugal force of the balanced weight to act on the master jaw in a direction substantially perpendicular to the sliding direction of the master jaw, thereby causing the master jaw to float. By canceling the moment, the lifting phenomenon of the jaw during rotation is prevented and the decrease in gripping force due to rotation is compensated for, and when the rotation is stopped, the initial gripping of the workpiece is improved. It returns to the original force and does not cause deformation of the workpiece after machining.

Therefore, by rotating the workpiece at high speed, the machining time can be reduced, manufacturing costs can be reduced, and the accuracy of the workpiece can be improved. In particular, it is capable of high-speed rotation of thin-walled workpieces and light alloy castings that are easily deformed by gripping, making it ideal for high-speed rotation chucks for all kinds of workpieces. Note that the present invention is not limited to the embodiments described above, and can be modified and implemented as desired without departing from the spirit of the invention.

For example, it is known that the jaws are slid in the radial direction by a driving means such as a fluid pressure cylinder so that the centrifugal force compensator in which the balance weight moves in the radial direction shown in the second embodiment can be used for a wedge-type chuck. The present invention can be applied to all types of chucks.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of the balance chuck according to the present invention, in which Figure 1 is a front view, Figure 2 is a vertical sectional view when the chuck is released, and Figure 3 is a sectional view taken along the line ■-■ in Figure 2. , Fig. 4 is a sectional view taken along ■-■ of Fig. 2, Fig. 5 is a vertical sectional view of another embodiment, Fig. 6 is a sectional view taken along -■ of Fig. 5, and Fig. 7 is a sectional view taken along An explanatory diagram showing the state when centrifugal force acts, Figure 8 is the first to
FIG. 4 is a diagram showing the rotation and gripping force of a 6-inch chuck, and FIG. 9 is a diagram showing the rotation and gripping force of a conventional 6-inch chuck. 1... Chuck body, 3... Master jaw, 4...
...Top jaw, 5...Jaw, 10...Balanced weight.

Claims (1)

[Claims] 1. In a chuck having a master jaw that is slidable in the radial direction within the chuck body in response to the operation of a fluid pressure cylinder, and a top jaw that moves in the radial direction together with the master jaw, the two jaws, the master jaw and the top jaw, A balance weight is provided on the chuck body to compensate for the centrifugal force of A balance chuck characterized in that a centrifugal force compensator configured to act in a direction substantially perpendicular to the master jaw is provided for each master jaw.