JPH0742589Y2 - Pallet gripping mechanism in automatic pallet changer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pallet gripping mechanism in an automatic pallet changing device in which at least two pallets attached to a machining center are sequentially changed by turning.

2. Description of the Related Art As a conventional two-face turning type pallet gripping mechanism, many grip types are used. For example, as shown in FIG. 4, a T-shaped engaging piece on the end face of the pallet is gripped by a grip that is hydraulically opened and closed. It is also known that a key is engaged in a recess as shown in Japanese Examined Patent Publication No. 61-58260 or FIG.

Problems to be Solved by the Invention The open-close type grip system has a problem in that a large gripping force cannot be obtained, and there is a danger that the pallet will shift in the turning direction during high-speed turning operation. For this reason, if the gripping force is to be increased, the hydraulic cylinder must be increased in size, and there is a problem in that the mounting location is restricted.

Further, in the case of the method of engaging with the recess, rattling of the engaging portion is unavoidable, and if rattling occurs, positioning becomes unstable during turning operation. Further, there is a problem that the turning operation becomes unstable and the possibility of hunting increases due to control, which makes high-speed operation difficult.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a pallet gripping mechanism that increases grip gripping force and improves swivel positioning accuracy.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides an arcuate engagement provided on the same circumference as the swivel center of a tween-shaped exchanging arm provided at the swivel center of a swivel pallet exchanging mechanism. In a two-sided swivel type pallet automatic exchanging device in which each part is engaged with an arcuate engaging part of a locking projection of the exchanging pallet and supported in a cantilever manner, the exchanging arm has an upper side fixed in a vertical position,
The upper side is a pair of upper and lower grip arms that can move up and down, and both can swing together, and the arc-shaped engaging portion that serves as a pallet turning radial direction engaging portion is provided on one of the grip arms.
Counterpart arcuate engagement parts are provided on the locking projections of the pallet, and their mutual pallet turning radial direction engagement surfaces are formed into tapered surfaces, and the pallet turning direction engagement part is provided on the other side of the grip arm. The engaging projections are provided on the locking projections of the pallet, and the engagement surfaces of the pallet pivoting directions are formed into tapered surfaces, and when the pair of grip arms grips the pallet, the pivoting radial direction and the pivoting direction respectively. A wedge force acts on the engaging surface of the.

Action The lower grip arm of the exchange arm pivotally positioned from the standby position to the pallet exchange position is pushed up, and the concave-convex engagement surface of the pivot direction engaging portion engages with the tapered surface to position the pivot direction and lock the pallet. The lower grip arm floats by cantilevering the protrusion, and the raised lower grip arm clamps the locking protrusion of the pallet with the upper grip arm fixed in the vertical position.

At this point, the concave-convex engaging surface of the arcuate engaging portion of the turning radial direction engaging portion engages with the taper surface to position the turning radial direction, and a wedge force acts on each of the turning radial direction and turning direction engaging surfaces. To do. Therefore, there is no gap in the engagement surface, and accurate gripping and positioning can be performed and pallet replacement can be speeded up by reliable gripping.

EXAMPLE An explanation will be given below with reference to FIGS. 1 to 3.

For example, a machine base 1 of a two-sided automatic pallet changing device is provided with a grip arm 2 above a twin-type changing arm concentric with a turning center for pallet changing and only rotatable by a bearing 15. On the lower surfaces of both ends of the grip arm 2, arc-shaped engaging projections 2a having a tapered cross-section centering on the turning center are provided on the same circumference. A grip arm 3 on the lower side of a twin-type exchange arm that is concentric with the turning center is provided below the grip arm 2, and a grip arm 3 on the lower side of a twin exchange arm is mounted on a machine shaft 1 that is vertically movable. The bearing 16 is provided so as to be relatively rotatable. On the upper surfaces of both ends of the grip arm 3, contact surfaces 5a for receiving tapered contact surfaces 14c at corners of a turning direction of a turning direction positioning projection 14b of a locking projection 14 of a pallet described later are tapered. A turning direction positioning recessed portion 5 is provided. Further, connecting pins 6 projecting upward are planted in the arm portion of the grip arm 3, respectively, and are fitted slidably into a through hole 2b formed in the arm portion of the grip arm 2 without any gap. The arms 2 and 3 can rotate integrally. A gear 7 is rotatably supported on the central shaft 4 via bearings, and the gear 7 is also rotatably supported on the machine base 1 via bearings 17. The grip arm 3 with respect to the gear 7 has a spline 19a on the outer periphery of a bearing pressing plate 19 fixed to the gear 7 with a bolt 18.
Are connected so as to be integrally rotatable and axially movable relative to each other, and when the gear 7 is turned by a motor (not shown), the grip arm 3 is turned at the same time. The central shaft 4 is configured to be pushed up with a strong force by a hydraulic cylinder or the like (not shown). Bearings when pushing up 16
The gripping arm 3 is also pushed up via the gripping arm 3 and the pallet is strongly cantilevered by the gripping arm 2 which is slightly floated by the cantilevering of the locking projection to fix the position.

Further, a compression spring 8 is inserted between the grip arms 2 and 3 so as to act in a direction to separate them.

The automatic pallet changer machine base 1 is arranged in front of the table of the machining center, and the machine base 1 transfers a semi-circular pallet on the circumference including the pallet on the table centering on the turning center at the time of pallet replacement. A surface 11 is formed. A large number of rollers 12 supported by horizontal shafts on the inner and outer surfaces of the pallet transfer surface 11 are pivotally supported, and a replacement pallet 13 is placed and positioned on the roller 12, so that the pallet is rotated with respect to the pallet on the machining center table. It is symmetrical with respect to the center. Each pallet 13 is provided with a locking projection 14 on the center side of the exchange turning, and an arc-shaped engaging groove 14a having a tapered cross section corresponding to the arc-shaped engaging projection 2a having the tapered cross section of the grip arm 2 is provided on the upper surface thereof. Is cut at a position where the grip arm 2 engages when the grip arm 2 turns to be in the same phase. Further, on the lower surface of the locking projection 14, a positioning contact surface 14c is formed in a taper at a corner portion in the turning direction corresponding to the tapered contact surface 5a of the turning direction positioning concave portion 5 of the grip arm 3 in the turning direction positioning. The convex portion 14b is formed.

In the thus-formed one, when a pallet replacement is instructed, the gear 7 is rotated by a motor (not shown), the grip arm 3 of the replacement arm in the standby position is rotated 90 °, and the grip arm is engaged with the connecting pin 6. It is positioned at the exchange position together with 2. The arc-shaped engaging projections 2a at both ends of the grip arm 2 in the exchange position are the respective pallets.
It is engaged with the arcuate engagement groove 14a of the locking projection 14 of 13.

The central shaft 4 is pushed up together with the grip arm 3 by the action of a hydraulic cylinder device (not shown). The tapered abutting surfaces of the swivel direction positioning recesses 5 on both ends of the grip arm 3 are tightly fitted to the tapered abutment surfaces 14c of the swivel direction positioning projections 14b on the lower surface of the locking projection 14 by a wedge force. The pallet 13 is cantilevered and slightly lifted and floated via the stop projection 14.
Due to this floating, the arcuate engagement groove 14a of the locking projection 14 is tightly fitted to the arcuate engagement projection 2a of the grip arm 2 by a wedge force, and is sandwiched between the grip arms 2 and 3. Therefore, the grip arms 2 and 3 and the locking projections of the pallet are integrally connected without any gap in the radial direction and the turning direction.

The gear 7 is rotated by driving a motor (not shown), and the grip arm 3 is swung via the bearing pressing plate 19. The grip arms 2 connected by the connecting pins 6 jointly rotate the pallet 13 on the table of the machining center while maintaining the holding state of the locking projections. The pallets on the table are simultaneously swiveled on the machine base 1 in the same manner. By switching the oil feeding direction of a hydraulic cylinder (not shown), the central shaft 4 is pulled down by the force of the compression spring 8 and the grip arm 3 is pulled down to lock the protrusion.
Release 14 pinch. A motor (not shown) is driven to rotate the gear 7 to rotate the grip arms 2 and 3 by 90 ° and return to the standby position.

It should be noted that the present invention is not limited to the positions of the arcuate engagement groove in the turning radial direction of the locking projection 14 and the turning direction positioning convex portion shown in the present embodiment, and it may be provided on the opposite side of the upper and lower surfaces or on the upper surface or the lower surface. Of course, the engaging portion of the grip arm is provided correspondingly.

That is, if the convex portion and the groove are provided so as to correspond to each other, the position does not matter.

Effects The present invention having the above-mentioned configuration has the following effects.

Since the gap between the grip arm and the engaging portion in the turning direction of the pallet in the turning radius direction and the turning direction is completely eliminated by the wedge action by the tapered surface, the turning speed can be increased and the exchange positioning becomes accurate.

[Brief description of drawings]

FIG. 1 is a partially omitted sectional view showing a grip arm and a pallet of the present invention, FIG. 2 is a plan view of an engaging portion between the grip arm and a locking projection of the pallet, and FIG. -A sectional view taken on the line A, Fig. 4 and Fig. 5 are views showing a conventional grip arm. 1 ... Machine base, 2, 3 ... Grip arm 2a ... Arc-shaped engaging projection, 4 ... Center axis 5 ... Turning direction positioning recess, 5a ... Contact surface 6 ... Connecting pin, 7 ... Gear 13 ... Pallet, 14 ... Locking protrusion 14a ... Arc-shaped engaging groove, 14c ... Abutting surface 14b ... Swivel direction positioning protrusion 19 ... Bearing retainer plate

Claims (1)

[Scope of utility model registration request] 1. An arcuate engagement portion of a locking projection of an exchange pallet, wherein arcuate engagement portions provided on the same circumference as the rotation center of a tween type exchange arm provided at the rotation center of a rotation type pallet exchange mechanism are concentric with each other. In a two-face swivel type automatic pallet exchanging device which engages with a portion and is supported in a cantilever manner, the exchanging arm has a pair of upper and lower grips in which the upper side is vertically fixed and the lower side is vertically movable so that both can swivel integrally. The arc-shaped engaging portion, which is an arm and serves as a pallet turning radial direction engaging portion, is provided on one of the grip arms, and a counterpart arc-shaped engaging portion is provided on the locking projection of the pallet, the pallet turning radial direction of each other. The engaging surface is formed into a taper surface, the engaging portion in the pallet turning direction is provided on the other side of the grip arm, and the mating engaging portion is provided on the locking protrusion of the pallet, and the engaging surfaces in the pallet turning direction are provided. Will be formed on the tapered surface, the turning radius direction when the pair of gripping arms gripping the pallet,
A pallet gripping mechanism in an automatic pallet changing device, wherein a wedge force acts on each engaging surface in the turning direction.