GB2072546A - An automatic bar stock feeder - Google Patents

Abstract

A automatic bar stock feeder for a machine-tool includes a flat guide plate (18) which remains stationary during the machine working cycle until, when the final stub of bar stock comes level with gripping jaws, it is moved by a rack and pinnion arrangement, of which the rack is formed on the guide plate (18), to provide for the raising and lowering motion for a bar guide cover (9) via a cam guideway (21), and to provide for opening and closing motion for the jaws, via two further cam guideways (19) and (20). The guide plate (18) also has a sloping cut out for providing motion to separating pins (12) which control separation of succeeding bars. <IMAGE>

Description

SPECIFICATION An automatic bar stock feeder The invention relates to apparatus for feeding bar stock in machine tools.

Diverse bar stock feeders for machine tools are known, having a greater or lesser complexity according to the machine they feed.

The loader intended for example to feed automatic machines in a continuous and accurate fashion comprises a side bar storage slop which leads into a channel wherein the bar is pushed by a thruster towards the machine.

Apart from the actual parts necessary to produce the continuous thrust on the bar stock, a series of devices is also necessary for removing the end of the expended bar, and replacing it by inserting one and one only of those stored on the slope, while a further requirement is that all this is accomplished in a continuous manner without interfering with the operation of the machine tool, said devices being accordingly governed by suitable electrical, electronic or similar control equipment.

These motions for replacing the bar stock require the application of a jaw that holds it, an opening and closing motion of the cover on the channel that accommodates the bar to be machined, and a means for separating the bottom bar on the storage slope from the rest so that it alone becomes positioned in the channel, and all this must be performed in a well defined series of movements, both in terms of time as well as space, and their relationship with one another.

The aforementioned motions were achieved on known machines by means of a series of exceedingly complicated arrangements, such as a circular cams, levers and springs whose movement was, due to the effects of inertia and others limited to a maximum speed that could not be exceeded, and this together with their inherent complex nature and multiplicity of moving parts, meant that such previous apparatus was not suitable for performing the quick and positive feed to modern machine tools which operate at high speed and have a high production rate.

It is for this reason that improvements are now herein provided for this kind of feeder, and more specifically for the above mentioned parts, in which the holding structure is still common to that used on previous machines, this comprising two sections that are parallel to the intermediate housing channel, and a side feeding slope. In such apparatus said parallel sections each have a parallel shaft positioned above it, and one of these shafts is secured by means of arms to the channel cover so that upon revolving, it will open said cover to admit a further bar.

Meanwhile, the shaft that lies parallel to the aforementioned one and beneath the feed slope, is attached to an eccentric to make pins rise and protrude at a certain time so as to separate the lowermost bar from the remainder thereof, and thus allow it to fall into the channel.

Above and below the centre channel, there are the two jaws of a clamp which upon closing together or opening away from each other, grip or release the bar, and the purpose of such gripping is either to hold the unwanted waste end during the return motion, or to secure the new bar until the thruster engages with it.

It is the object of this invention to provide an automatic bar stock feeder in which all the required movements are carried out in a particularly advantageous way, to enable the bar feed to operate in a manner appropriate to modern machine tools.

According to the present invention there is provided an automatic bar stock feeder including a guide plate of a generally flattened parallelepiped shape, upon one of whose larger faces and along the whole length thereof, is a toothed rack engageable with an output gear wheel from a motor reducer unit, allowing said guide plate to selectively travel forwards or backwards, while upon the opposite larger face of the guide plate, there are guide ways that each accommodate respective followers, and of said guide ways fulfilling the purpose of raising and closing the cover on a pipe in which the bar stock travels, while two further guide ways cause jaws that grip the bar stock to open and close, and the said guide plate possessing a sloped area which continues along one of its larger faces to provide a travel motion that will make a bar to bar separating pin mechanism operate.

All the mechanisms are thus governed by a single guide plate having the shape of a parallelepiped and being located between two frame sections underneath the thrusting channel in such a way that on the said one of the larger face of said guide plate, there are the three machined guide ways, of which two are tapered towards each other, which with their followers make the gripper jaws open and close, whilst the third makes the channel cover rise or descend.

Preferably said guide plate is also provided on its opposite face with a groove at one of its ends so that by means of a lever, it will raise the bar separating pins, while on the this same face of the guide plate, there may also be a machined rack which, by means of a stationary pinion, makes the guide plate move forwards and backwards in its travel thus automatically defining the bar change-over motions.

This series of improvements in the transmission and the achievement of the different synchronized motions due to the new design of the assembly, together with its optimization as achieved by careful consideration being given to speeds, accelerations and inertias in all working parts, mean that significant im provements are embodied in this bar stock feeder.

In order to provide a fuller understanding of the nature of the invention, the attached drawings show embodiments constructed in accordance with the invention. In the draw ings; Figure 1 shows an elevational view of the complete bar stock feeder constructed in ac cordance with the invention, Figure 2 is a cross section view of the feeder showing the bar feeder slope with one of its separating pins, and the central channel with its swinging cover, Figure 3 is a detailed view showing one of the levers attached to the cover on the chan nel.

Figure 4 is a view of the drive to the side shaft which raises separating pins, Figure 5 is an elevation view showing the attachment of an eccentric to shaft depicted in Fig. 4, Figure 6 is an elevation view of a guide plate, Figure 7 is a plan view of the guide plate, Figure 8 is a rear elevation view of the guide plate, Figure 9 is a cross-sectional view of the guide plate on the plane shown in Fig. 6, Figure 10 is a detailed view of the drive mechanism for the lifting shaft that raises the cover on the channel, Figure 11 is a partial cross section view of the feeder that allows the attachment of the guide plate to the main frame to be seen and, Figure 12 is an elevation view of the above.

The drawings shown an automatic bar stock feeder which is seen in a general view in Fig.

1. This has a frame comprising two parallel sections 1 (shown in Fig. 2) upon which there is mounted a channel 2 in a coaxial position with the machine tool chuck (not shown), so that the bar stock to fed slides along this channel 2 upon being pushed by a thruster.

As may be seen from Figs. 1 and 2, a plate having a sloping surface 3 is provided upon one of the sides. Arms 4 are attached to supports 5, so that these arms can be placed nearer to or farther from the slope plate 3 in order to cater for bar stock of differing diame ters.

The apparatus has thrusting components, and synchronizing contacts or breakers, and other components related to the bar stock changeover mechanism. This may be divided into three sub-assemblies for carrying out the motion of a cover 9 on the channel 2, the gripping of the bar by jaws 30 and 31, and the separation of the last bar on the slope plate 3 from the remainder.

Above the frame sections 1 there are, as seen in Fig. 2, two shafts 6 and 7 parallel with one another, the shaft 6 having levers 8 solidly attached both axially and radially thereto, while the opposite ends of such levers 8 are joined to the cover 9 of the channel 2, so that rotation of shaft 6 through a given amount of angular travel will, depending upon its direction of motion, cause either the opening or the closing of the cover 9 on the channel 2, so as to allow or prevent entry of a futher bar.

Shaft 7 located beneath the slope 3 has thrusters 11, which are eccentric to the axis, attached to it so that they travel with it when in motion, and said thrusters 11 act upon the bottom ends of separating pins 12 accommo- dated in a plurality of housings on the bottom of the slope plate 3. These thrusters 11 which, operating against the pressure exerted by springs 13, cause separating pins 12 to emerge with respect to the surface of the slope plate 3 so as to separate the last piece of bar stock, and prevent the remainder from falling.

The separating pins 12. which have a fixed and specific position at the bottom end of the slope 3, operate in conjunction with supports 10 located upon the cover 9 of channel 2, in such a way that between said supports 10, whose position in the horizontal direction can be varied with respect to the cover 9, and separating pins 12. there is defined only enough space for a single piece of bar stock to lie, regardless of its diameter.

In addition to the aforementioned eccentric thrusters 11, shaft 7 has a sleeve 14 the position of which can be adjusted both axially and radially at will as may be seen in Fig. 5, and said sleeve 14 carries an eccentric 15.

which is governed by a pin 17 housed in a transverse guide pin 16. Travel of the pin 17 in the horizontal direction causes shaft 7 to revolve through an angle, and hence the separating pins 12 to rise and overcome the pressure exerted by springs 13.

The advance of the pin 17 is achieved by a guide plate 18 of which the general shape is that of a parallelepiped, as may be appreciated from Figs. 6, 7, 8 and 9. One of the larger faces of such guide plate is machined with three guide ways 19, 20, and 21, of which the first two fulfill the purpose of opening and closing jaws 30 and 31, and the third 21 that of closing the cover 9.

Guide plate 18 is moreover provided on it opposite larger face, with a cut out 22 at,one of the edges, to cause horizontal motion of the aformentioned pin 17 which operates the separator pins 12. and also a toothed rack 23 that is in engagement with pinion 36, Rotation of this pinion 36 causes the guide plate 18 to undergo motion.

Sleeves 34 that are cylindrical in shape and engage with two parallel guide bars 35 attached to one of the frame sections 1 as seen in Fig. 12, are moreover embodied into that face of guide . 1 8 which carries toothed rack 23, so that said guide bars 35 allow the guide plate 18 to slide freely between the frame sections 1 when driven by stationary pinion 36. the pinion 36 is driven by a motor reducer gear unit and is automatically controlled by a series of travel limit switches or similar control gear.

A follower roller 24, which is solidly attached at right angles to an arm 25 that is capable of sliding freely in the vertical direction, is located on guide way 21 which, as may be seen from Fig. 6, is in the lowermost position and comprises a horizontal length with a rise at the end, and said arm 25 is linked by means of a pin accommodated in an oblong hole 26, to a lever 27 that is secured to the spindle or shaft 6.

The forward travel of guide plate 18 makes shaft 6 revolve to a certain specific position through roller 24 and lever 27 when said guide plate reaches the end of its range, while, as may be seen from Fig. 2, said shaft 6 is connected to the cover 9 which, during such rotation, lifts away from channel 2 to allow another bar to be admitted, and closes again when guide plate 18 returns.

Guide ways 19 and 20, located, as shown in Fig. 6, on the upper face of the guide plate 18 converge and diverge and accommodate follower rollers 28 ahd 29. The roller 28 is secured to an arm positioned at right angles, which is able to slide freely in the vertical direction, and embodies the lower jaw 30.

The roller 29 is likewise secured to an arm at right angles having an oblong hole in the centre, and said arm is capable of sliding freely in the vertial direction, whilst at its upper end, it is provided with an overhang 32 which embodies, together with an intermediate dampening spring 33, an upper jaw 31 terminating in a point, and which, like the lower jaw 32, is constructed from material with a high degree of hardness and locks upon the bar stock with no appreciable wear.

When guide plate 18 begins its motion, rollers 28 and 29 which are engaged respectively, in guide ways 19 and 20, hold the jaws away from each other, as may be appreciated from Fig. 11. When guide plate 18 travels forward, the rollers travel along portions of the guideways 19 and 20 which diverge, and this causes the upper jaw 31 and lower jaw 30 to approach one another and grip the end of the expended piece of bar stock, and the jaws then open not symmetricall to the first position, as seen in Fig. 6, along guide ways 19 and 20, with the lower jaw 30 travelling faster and both opening to a greater degree, so as to facilitate the fall of the expended piece of bar and allow the insertion of the new one.

An explanation is now given as to the operation in order to change over to a new piece of bar stock with the removal of the expended piece.

In the course of the working cycle, that is to say whilst the bar is being pushed, guide plate 18 remains stationary. When the bar stock being fed along the channel 2 by the relevant thruster becomes expended, a signal is given which makes said thruster withdraw together with the rest of the bar. During this withdrawal and at a specific time, pinion 36 begins to operate and, meshing with rack 23, makes guide plate 18 travel from a position such as that illustrated in Fig. 6, towards the left.

The first motion caused by the guide plate 18 travel is that one due to its cut out 22, which makes a pin 17, steadied by guide 16, undergo travel through the eccentric to shaft 7, and this, as has been described above, makes separator pins 12 emerge and separate the bottom bar on the slope plate 3 from the rest.

Due to the shape of the guide ways 19 and 20, travel motion of guide plate 18 makes jaws 30 and 31 close and grip the end of the expended piece of bar stock, and remove it from the thruster, and shortly aftrwards said jaws open in a non-symmetrical sequence and allow the stub of bar stock to drop, whereafter they remain open.

The guide way 21, through arm 25 and lever 27, makes shaft 6 revolve, which, makes cover 9 open, this being joined to supports 10 which therefore allow the bottom piece of bar stock to drop into the channel 2, and take the place of the old one.

Once this stage has been reached the guide plate 18 begins travelling in the opposite direction, under control from conventional kind of automatic control equipment, and it then repeats the motions in reverse order.

First the cover 9 is closed, and then the jaws 30 and 31 close to offer the new piece of bar stock to the thruster. Jaws 30 and 31 next open, and finally, before guide plate 18 ceases its motion, pin 17 returns and this, due to the force exerted by springs 13 will cause separating pins 12 to be lowered and thus allow a further piece of bar stock to fall into the position where it is ready.

Claims (7)

1. An automatic bar stock feeder including a guide plate of a generally flattened parallelopiped shape, upon one of whose larger faces and along the whole length thereof, is a toothed rack engageable with an ouput gear wheel from a motor reducer unit, allowing said guide plate to selectively travel forwards or backwards, while upon the opposite larger face of the guide plate, there are guide ways that each accommodate respective followers, and one of said guide ways fulfilling the purpose of raising and closing the cover on a pipe in which the bar stock travels, while, two further guide ways cause jaws that grip the bar stock to open and close, and the said guide plate possessing a sloped area which continues along one of its larger faces to provide a travel motion that will make a bar to bar separating pin mechanism operate.

2. An automatic bar stock feeder as claimed in claim 1 wherein the guide ways for causing jaw travel are arranged so as generally to converge and have an initial length for straight travel during which the jaws remain open, followed by a curved length when the jaws close, and ending finally in a further straight length of travel when the jaws are open.

3. An automatic bar stock feeder as claimed in claim 1 in which the guide way for the cover begins with a straight length operative when the cover is closed, and this straight length extends along practically the whole of the guide plate, and ends in a curved length, when the cover is open.

4. An automatic bar stock feeder as claimed in any one of the preceding claims in which the guide plate remains stationary during the machine working cycle, and commences its travel when a stub of expended bar stock reaches the jaws so as to make them close in the first stage of its travel and thus allow the thruster to become free of said stub, whereafter said jaws open and allow said stub to drop, until finally the cover is raised in order to admit a new piece of bar stock, where such admission causes control equipment such as travel limit switches to operate so as reverse the direction in which the guide plate is travelling and perform its cycle in reverse.

5. An automatic bar stock feeder as claimed in claim 1 or claim 3 wherein the follower in the guide way for raising the cover is assembled upon the end of an arm the opposite end of which is, by means of a pin and oblong hole arrangement, linked to a lever which is radially attached to a shaft upon which are affixed further levers connected to the lid so that when the aforementioned arm travels, the shaft rotates and raised or lowers the cover, stops for the first bar on the feeder slope being secured to said cover.

6. An automatic bar stock feeder as claimed in claim 1 in which the bar to bar separating mechanism comprises a number of pins assembled upon housings that are fixed to the lower part of the feeder slope, said pins protruding through said slope in order to fulfill their purpose as separating means, and are connected to springs which press them towards their concealed or non-operational positions, and such pins being held in opposition to the pressure exerted from said springs by levers that are secured to a shaft which is in turn held in its radial position by a pin that is in contact with the guide plate in such a manner that when said pin is positioned upon the aforementioned sloping area, it allows the shaft to revolve and hence the separating pins to be withdrawn or concealed.

7. An automatic bar stock feeder substantially as hereinbefore described with reference to and as shown in the accompanying drawings.