GB2256382A - Automatic tool changer. - Google Patents

Abstract

The changer has a change arm (31) to exchange tools between a tool magazine (37) and a machine tool spindle (35) and swings through 90 DEG in a horizontal plane and moves laterally from terminal positions of the swinging movement. A guide roller (41) is provided on a base (38) of the change arm (31) and a stationary guide plate (43) has a guide groove (44) in which the roller (41) can engage when at the terminal positions of the swinging movement and in which it is then constrained to move. The guide groove (44) is curved and a detection sensor is provided to detect the guide roller (41) moving in the groove (44) and to give rectilinear drive to the change arm base on a swinging support (34). The tool changer provides for more rapid tool changing since previous successive moves are made practically simultaneous. <IMAGE>

Description

AUTOMATIC TOOL CHANGER The invention relates to an automatic tool changer.

Such an automatic tool changer can be used with a machine tool and can provide a tool changing device between a tool magazine and a spindle head which travels rectilinearly and swings horizontally.

In a conventional automatic tool changer of this kind and as shown in Figure 4 of the accompanying drawings, a change arm 21 of the automatic tool changer is supported on a lateral travelling rail 24 of a swinging bracket 23 which swings around a shaft 22.A tool T1 of a tool magazine 26 and a tool T2 of a spindle 25 are to be exchanged in a sequence as follows: Firstly, the tool T1 kept in a tool pot 27 of the tool magazine 26 is taken out by a series of operations of the change arm 21 from a starting position S, which operations comprise lateral movements and projection/retraction of the change arm 21 indicated by arrows 1 to 4 in Figure 4. After swinging movement indicated by an arrow 5, the change arm 21 is stopped at a waiting position W, and it travels to the left as indicated by an arrow 6. Next, it swings further in the same direction, as indicated by an arrow 7, to a position at an angle of 900 from the position of the tool magazine 26.Then, it travels to the right as indicated by an arrow 8, to permit a grip on one end of the change arm 21 to grasp the tool T2 of the spindle 25. After the change arm 21 is projected as indicated by an arrow 9 so as to take out the tool T2, it vertically revolves through 1800 as indicated by an arrow 10. After that, it is retracted as indicated by an arrow 11 so as to fit the tool T1, to the spindle 25, and it travels to the left as indicated by an arrow 12, thus releasing the change arm 21 from the spindle 25. Subsequently, it swings to a waiting position W as indicated by an arrow 13, and it travels to the right as indicated by an arrow 14 and is stopped, waiting for a next step.As a result of complemental swinging movement of the change arm 21 indicated by an arrow 15 and magazine-side lateral movements and projection/retraction of the change arm 21 indicated by arrows 16 to 19, the tool T2 is put in the tool magazine 26. Eventually, the change arm 21 returns to the starting position S. Tools are exchanged by the above-described operations in the order of 1 to 19.

In this case, a period of time required for tool exchange can be reduced by effecting, almost simultaneously the operations 4 to 7, i.e.

the arm retraction 4 at the right terminal position on the magazine side, the swinging movement 5 to the waiting position, the stoppage and movement 6 to the left, and the swinging movement 7 toward the spindle, and by effecting, almost simultaneously, the operations in the counter order from the movement 12 to the left on the spindle side to the swinging movement 15 toward the magazine. For this purpose, it is necessary to perform horizontal swinging and lateral travelling of the change arm 21 mechanically in association with one another and to eliminate the steps of stoppage at the waiting position W.

In order to satisfy this necessity, under the circumstances, there has been proposed a tool changer in which a phantom point where the magazine-side right terminal position coincides with the spindle-side left terminal position is recognised with respect to the change arm base 28 fixed to the lateral travelling rail 24 of the swinging bracket 23, the change arm base 28 being arranged to swing around such a phantom point. A cam-follower is provided for maintaining the phantom point at the same location during the swinging movement. The above coincidence point can be suitably selected by combination of a stationary cam and a rotating cam. A tool changer of this kind has a complicated structure including a large number of component parts, and it is not sufficiently practical because it requires frequent maintenance.Besides, a period of time required for tool exchange cannot be satisfactorily reduced by this tool changer.

According to the invention there is provided an automatic tool changer in which a change arm for exchanging tools between a tool magazine and a spindle of a machine tool swings through 900 in a horizontal plane and travels laterally from or to the respective terminal positions of swinging movement, the tool changer including a guide roller mounted on the bottom surface of a base of the change arm and a guide plate provided on a stationary base, which guide plate has a guide groove in which the guide roller can move, the groove of the guide plate being defined to have corners at positions of the guide roller within the guide groove when the change arm is located at the terminal positions of swinging movement and to be curved between the corners, and the tool changer further including a detection sensor which detects existence of the guide roller moving in a curved portion of the guide groove and gives rectilinear drive to the change arm base.

In contrast to a conventional tool changer such an automatic tool changer can effect quick tool exchange wherein the operations 4 to 7 can be performed substantially together when the arm retraction II at the magazine-side right terminal position is followed by the swinging movements 5 and 7 toward the spindle almost simultaneously with the movement 6 to the left, whereas the operations 12 to 15 can be performed substantially together when the movement 12 to the left on the spindle side is followed by the swinging movements 13 and 15 toward the magazine almost simultaneously with the movement 14 to the right.

When the guide roller swings from such a corner position and enters the guide groove, rectilinear drive can be given to the change arm to perform swinging movement and rectilinear movement together.

Therefore, two detection sensors may be provided adjacent to openings of the groove at these corner positions, or one detection sensor may be provided at an intermediate position of the groove so as to serve as a common sensor for movements to the left and right. Preferably, the detection sensor in actual use is located at a centre position of the swinging bracket. Alternatively, it may be provided on the guide plate so as to detect the position of the guide roller.

In the conventional case, the change arm is usually designed to move from the starting position in such a manner that movements to the left and right and 900 swinging movements in the operations 1 to 19 are carried out separately. In a tool changer of the invention, the guide roller is provided on the base of the change arm, and the guide roller moves along the guide groove on the stationary base, thus enabling swinging movement and rectilinear movement of the change arm to be performed simultaneously. Thus, together with the swinging movement of the change arm, the guide roller moves from one of the corner positions to the other without leaving the guide groove.

When the swinging movement begins after the rectilinear movement, rectilinear drive supply is cut off to free the change arm base by the rectilinear drive detection sensor located at the intermediate position of the guide groove. In the middle of the swinging movement, rectilinear drive is given at the change arm base, thereby achieving the completion of the swinging movement and that of the lateral movement almost simultaneously. Thus, when the guide roller reaches the left terminal position on the spindle side of the right terminal position on the magazine side, the above-described operations 4 to 7 or 12 to 15 are completed together, and immediately followed by the movement 8 to grasp the tool of the spindle or the arm projection 16 to put the tool in the magazine.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which: Figure 1 is an explanatory plan view of a tool changer according to the invention; Figure 2 is an explanatory front view of the tool changer of Figure 1 but with a change arm portion omitted; Figure 3 is an explanatory plan view of a swinging guide plate of the tool changer of Figures 1 and 2; and Figure 11 is a schematic plan view of a tool changer of previously proposed kind.

Referring to the drawing and firstly to Figure 1, a tool pot chain 27 of a tool magazine 26 is provided on the left side of the drawing, and a spindle 35 is provided on the right upper side of the drawing. Exchange of tools between these two members is performed by a change arm 31. A change arm base 38 provided with a travelling motor 46 is movably supported on a travelling rail 34 of a swinging bracket 33 which swings through 900 around a swinging shaft 32, so that the change arm base 38 can travel laterally and rectilinearly from a position indicated by a solid line to a position on the left indicated by a chain double-dashed line in the drawing. Three sensors 45L, 45C and 45R to detect a position of the change arm base 38 are provided on the swinging bracket 33 at the left terminal position, the centre and the right terminal position, respectively.

The swinging bracket 33 swings through 900 from a position indicated by a solid line to a position on the centre upper side indicated by a chain double-dashed line in the drawing. For this purpose, there is a swinging cylinder 47 which includes a detection sensor 48M on the magazine side of a cylinder rod and a detection sensor 48s on the spindle side of the cylinder.

The structure of the tool changer described above is similar to that of the conventional apparatus except for the sensor 45C to detect the centre position of the change arm base 38. As shown at the lower part of Figure 2, a guide roller 41 is provided on the bottom side of the change arm base 38 in such a manner that the guide roller 41 can move along a guide groove 44 in a guide plate 43 which is fixed on a stationary base 42. The shape of the guide plate 43 is shown in the plan view of Figure 3. In this Figure, there are also shown the shapes and positional relationships of the swinging shaft 32 of the swinging bracket 33, the guide roller 41 and the guide groove 44 as well as the positions of the change arm 31 when displaced.

The guide groove 44 is defined to have an open end along a direction of positions O-P of the guide roller 41 in the magazine-side lateral movement and an open end along a direction of positions Q-R of the guide roller 41 in the spindle-side lateral movement. The guide roller position P is the right terminal position of the magazine-side lateral movement while the roller position Q is the left terminal position of the spindle-side lateral movement. The guide groove 44 has such a shape that a smooth curve can be depicted between the positions P and Q. Consequently, when the change arm 31 is swung in a condition free to travel, it moves in a direction opposite to the movement from O to P or from R to Q, while swinging with the guide roller 41 moving between P and Q, so as to be ready for the next step.When the guide roller 41 passes an intermediate position between P and Q, i.e. in the middle of the movement in the opposite direction of the movement to the right or left, the centre position detection sensor 45C is struck by the change arm base 38, so that the change arm base 38 which has been free to travel starts to be driven to travel to the left in the case of swinging movement toward the spindle 35 with the guide roller 41 moving P to Q or driven to travel to the right in the case of swinging movement toward the magazine 36 with the guide roller 41 moving Q to P.

Thus, horizontal swinging and lateral movement can be completed almost simultaneously and immediately followed by the next step.

The tool changer of Figures 1 to 3 enables tool exchange to be performed quickly and reliably by associating the function of the guide plate and the operation for starting to drive the change arm base upon the detection at the intermediate position of the guide groove. Thus, a period of time required for tool exchange can be reduced, which results in improvement of operational efficiency. Moreover, this tool changer need only require a small number of additional component parts, and can have a simple and highly reliable mechanism, so that the tool changer can be manufactured at low cost and maintenance can be readily performed.

Claims (3)

1. An automatic tool changer in which a change arm for exchanging tools between a tool magazine and a spindle of a machine tool swings through 900 in a horizontal plane and travels laterally from or to the respective terminal positions of swinging movement, the tool changer including a guide roller mounted on the bottom surface of a base of the change arm and a guide plate provided on a stationary base, which guide plate has a guide groove in which the guide roller can move, the groove of the guide plate being defined to have corners at positions of the guide roller within the guide groove when the change arm is located at the terminal positions of swinging movement and to be curved between the corners, and the tool changer further including a detection sensor which detects existence of the guide roller moving in a curved portion of the guide groove and gives rectilinear drive to the change arm base.

2. An automatic tool changer according to claim 1, wherein the detection sensor is located at the centre of a travelling rail for the change arm base.

3. An automatic tool changer substantially as hereinbefore described and illustrated with reference to Figures 1 to 3 of the accompanying drawings.