Turning – Lathe – With work feeder or remover
Reexamination Certificate
1998-09-04
2001-03-13
Tsai, Henry (Department: 3722)
Turning
Lathe
With work feeder or remover
C082S125000, C082S126000, C082S127000
Reexamination Certificate
active
06199461
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an automatic bar feeder device, especially for CMC lathes, which is to be used in a magazine bar feed, and comprising a device for transferring a bar to be machined from a hopper on a bench, and a device for advancing said bar into the lathe, this advancing device containing a short advance module equipped with a flag, and a long advance module equipped with a thrustor.
Feeder devices, comprising a bar loading device, a device for their advance, and a centering device, are used in apparatuses currently called “magazine bar feeds” of which different types are on the market.
The task of these apparatuses is to automatically feed especially automatic or CNC lathes; automatic feed sensibly increases the yield of the latter and substantially reduces the unit costs of the pieces machined on the lathes of this kind.
2. Description of the Prior Art
Known magazine bar feeds generally have the shape as shown, in a very schematical manner, in attached
FIGS. 1A and 1B
(side and front view, respectively) : There is a frame
10
, a cradle
11
within the frame, a bench
12
shaped as a very open V, said cradle being optionally covered by a hood
13
, and an inclined plane hopper
14
whose inclination can be adjusted by the device
15
. A bar
17
which is laid down on the bench
12
has beforehand been transferred from the hopper
14
on said bench. The bar is to be machined on a lathe, represented by a mandrel
19
and a headstock
9
, after having been introduced in this headstock by an advance device
18
.
The functional principle of known feeder devices can easily be understand from
FIG. 2A
to
2
F which show a lateral view of such a device:
In
FIG. 2A
, the bars to be machined
17
A,
17
B,
17
C etc. are placed or stored on the hopper
14
and blocked there by a shoulder
14
A. The bench
12
and a set of grippers
16
(from which only one is shown) connected thereto are in a defined position which corresponds to that shown in
FIG. 2D
in such a manner that, when a bar
17
A is placed on the V, its axis and the axis of the headstock of the lathe would have the same support.
In a first step, the unit
12
,
16
rises, the grippers lift the first bar
17
A according to the vertical arrow (
FIG. 2B
) until said bar swings over the shoulder
14
A of the hopper
14
(
FIG. 2C
) and falls all of a sudden into the V of the cradle (
FIG. 2D
, showing the position of the bench
12
where the axis of the bar
17
A and that of the lathe headstock have the same support). During these operations, the next bar
17
B is held back by the rear flank of the gripper
16
.
In a second step (not shown), a short thrustor called flag (first module of an advance or thrusting device) pushes the bar to be machined into the lathe headstock.
In a third step, the unit
12
,
16
goes down according to the arrow (
FIG. 2E
) until it takes its original or starting position of
FIG. 2A
(FIG.
2
F). Simultaneously, the next bar
17
B which is no longer held back by the gripper
16
, rolls on the inclined plane of the hopper
14
(see arrow in
FIG. 2F
) and comes to rest against the shoulder
14
A which blocks the travel.
Finally, in a fourth step, the flag goes back and gives room for a long thrustor (second element of the advance device) whose function is to take care of the advance or the succeeding advances of the bar until its complete machining, according to the strokes shown in
FIGS. 3A
to
3
D: The material advance (namely that of the bar
17
A) is effected by the action of the thrustor
18
, the jaws of the mandrel
19
being open (FIG.
3
A). The bar is then clamped (FIG.
3
B), and the machining is undertaken (
FIG. 3C
) When the machining is finished, cutting off is made (FIG.
3
D), and a new machining cycle can be started, for example on the same bar
17
A; this is to say that the mandrel jaws open, the thrustor
18
is advanced and pushes the bar
17
A over a defined distance, etc.
These known apparatuses and devices have several kinds of disadvantages.
First, the loading operations come about brutally since the apparatus is subject to two succeeding shocks during each of these operations.
A first shock comes from the fall of the bar
17
to be machined (
17
A,
17
B, etc. in
FIGS. 2A
to
2
F) into the V of the bench down from the grippers (FIG.
2
C).
A second shock occurs from the fall of the next bar
17
B against the stop shoulder
14
A of the hopper (see FIGS.
2
E and
2
F), this bar being itself under the push of the higher bars
17
C,
17
D, etc. (FIG.
2
F).
As a rough indication, the weight of a sole bar having a diameter of 80 mm and a length of 1,200 mm is about 47 kg.
It can easily be understood that these shocks, as to their effects, will be damaging to the magazine bar feed itself as well as to the lathe which it feeds. More particularly, the shocks provoke an increasing misalignment between the magazine bar feed and the headstock of the lathe at such an extent that, from a certain moment, the bars will hit the headstock which will thus cause serious damages (especially destroying the bearings of the headstock, resulting in worse machining precision and reduction of the lifetime of the lathe).
Another serious drawback is the absence of any apparatus polyvalence since the known devices only allow the loading of bars and not their unloading. However, in some cases, for example when bars should be machined at one end, it would be advantageous to unload these bars after machining by means of the magazine bar feed.
In certain known magazine bar feeds, the advance device comprises two parallel disposed cylinders which are next but distant to each other, a first cylinder coacting with the short thrustor (flag) and a second one with the long thrustor. The loading comprises three steps: first, the introduction of the bar by means of the flag, driven by the first cylinder, and the retreat of said flag; then, a lateral displacement of the two cylinders by means of a horizontally movable carriage, in order to place the long thrustor in the headstock axis, namely the bar axis; and finally the advance of the long thrustor, driven by the second cylinder. Other known magazine bar feeds are equipped with two thrusters, a short and a long one, vertically superimposed and mounted on a vertically movable carriage. In still other known magazine bar feeds, already more improved, the two thrustors are mounted on a seesaw, the short thrustor or flag making the first introduction and the long thrustor pushing the bar into the headstock for machining, these two thrusters being driven by the same cylinder but the seesaw remaining driven by a separate cylinder. All these devices would be improved when they were less complicated, more purposeful and less expensive.
Regarding known centering devices, their handling is not easy, and the centering operations are carried out neither quickly nor purposefully.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a device which overcomes the described drawbacks and whose manufacture is moreover less expensive. This object is met by the device of this invention wherein the bar loading device comprises means which coact in such a manner as to avoid any shock exerted by the bar against any element of the magazine bar feed, especially against the bench and the hopper, during the loading of the bar. Furthermore, the flag and the thrustor are driven by one and the same element alone, the short advance module and the long advance module coacting by means allowing their coupling an uncoupling.
Inventive details and special or preferred embodiments are disclosed and defined in the following description and the dependent claims.
REFERENCES:
patent: 3353688 (1967-11-01), Kuckelsberg
patent: 3937331 (1976-02-01), Spercel
patent: 4423651 (1984-01-01), Hardee
patent: 4604924 (1986-08-01), Cucchi
patent: 5320008 (1994-06-01), Cucchi
patent: 5556253 (1996-09-01), Rozendaal
patent: 5662014 (1997-09-01), Link
patent: 735 412 (1969-12-01), None
patent: 000676939 A5 (1991-03-01
Foley & Lardner
Tsai Henry
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