WO2022144583A1

WO2022144583A1 - Short bar feeder

Info

Publication number: WO2022144583A1
Application number: PCT/IB2021/000019
Authority: WO
Inventors: Paolo RASPANTI; Fabio RASPANTI
Original assignee: Raspanti Paolo; Raspanti Fabio
Priority date: 2020-12-28
Filing date: 2021-02-08
Publication date: 2022-07-07

Abstract

The short bar feeder includes a storage area (1) for at least one bar (2) and a loading device (3) which loads one bar (2) at a time. II is also equipped with a variable length bar pusher (4) and three self-centering devices (5A, 5B, 5C), which support the self-centering supports (5A,5B, 5C) which support both the bar (2) and the variable length bar pusher (4).

Description

Short bar feeder”.

Field of the invention.

The invention concerns a short bar feeder equipped with a variable-length bar pusher and three self-centering devices designed to load bars on CNC lathes. This bar feeder is capable of loading bars of length up to 1830 mm (i.e. 6 ft), regardless of the spindle length. This bar feeder is equipped with a variable length-bar pusher and three self-centering devices which control and support both the bar and the variable-length bar pusher within the short bar feeder.

State of the art.

Short bar feeders currently available on the market share four main features: - they cannot load bars longer than the lathe’s spindle; - they cannot recover the remnant; - bars cannot rotate inside them; - their length ranges between 1 .8 and 2.5 m (5.9 to 8.2 ft). The standard length of commercially available bars is: - 3 m in continental Europe; - 12 ft in North America; - 4 m in the United Kingdom and other countries. Given the current features of short bar feeders, the bars have to be cut into sections whose length cannot exceed the spindle length. For a lathe with a short spindle (500 mm), for instance, a 4 m long bar needs to be cut into eight sections, whereas , for a 1300 mm long spindle, a 3 m long bar will be cut into three sections. This has a considerable influence on the production costs.

Invention summary.

The object of the present patent is a short bar feeder equipped with a variable-length bar pusher and three selfcentering devices, which provides the following benefits to the end user: - reduction of bar cuts to just one; - remnant recovery; - rotation of the bar within the bar feeder relying on the three self-centering devices; - footprint in line with the currently available short bar feeders; - increase of the lathe’s unattended production capacity, since the gain in maximum bar length increases the amount of material than can be loaded onto the storage area. These and other advantages of this invention will be better explained in the following sections, where a detailed description of the preferred, although not exclusive, configuration will be given. The description will be given with reference to the attached drawings, which have an explanatory purpose and do not constitute a limitation to further applications or modifications.

Brief description of figures.

Figures 1 and 2 are side views of the variable-length bar pusher at maximum and minimum extension, respectively. The variable-length bar pusher’s total length at the maximum extension configuration is 1600 mm. The variable-length bar pusher consists of a fixed component 50, which is approximately 300 mm long, and a moving component 51 which is approximately 700 mm long (the total working stroke of the variable-length bar pusher is 600 mm). The variable-length bar pusher’s total length at the minimum extension configuration (closed position) is therefore 1000 mm. Figure 3 is an overall view of the bar feeder, where the bar storage 1 , the bar 2, the bar loading device 3 and the three self-centering devices 5A, 5B and 5C can be seen.

Detailed description.

The short bar feeder includes a storage area 1 for at least one bar 2 and a loading device 3 which loads one bar 2 at a time. II also equipped with a variable-length bar pusher 4 and three self-centering devices 5A, 5B and 5C, which support both the bar 2 and the variable-length bar pusher 4 based on their position within the bar feeder. The bar 2, which has a maximum length of 1830 mm, is held onto the bar pusher 4 by the collet 16, which is mounted on the rotating portion of the bar pusher (i.e. the rotating tip). The bar is then inserted into the spindle and moved according to the direction from HM1 15 (the movement could be determined, for instance, by the machined part’s length), regardless of the spindle length or other features, such as the length of the bar feeder or other component, allowing 1830 mm long bars to be machined. The horizontal movement of the variable- length bar pusher 4 is determined by a numerical control electric motor 6 through a transmission system 7, such as a lead screw or a timing belt, secured to the back of the variable-length bar pusher 4. The extension of the variablelength bar pusher 4 is changed by a double acting pneumatic cylinder 10 , which has a piston 8 connected to a rod 9. The movement is controlled by a standard pneumatic system 11 . The electric motor 6 that drives the variable-length bar pusher 4 is fitted with an encoder 12, which verifies the position of both the variable-length bar pusher 4. The electric motor 6 and the encoder 12 are connected to an ALU 13, such as a PLC with HMI unit 15, and monitor 14. The variable-length bar pusher 4 has a fixed 50 and moving component 51 , and it features a rotating tip 17 on which a collect 16 is fitted. The needed mechanical and electronic connections can be easily performed by a trained technician, as they are done using well-known techniques. In working mode first a new bar 2 is picked up from the storage area 1 by the loading device 3, supported by rollers. The loading device aligns the bar’s axis with the spindle center. Once the bar 2 is positioned onto the rollers, it is moved forward by the feeding finger 18, which is mounted on the back end of the variable-length bar pusher 4, until it reaches the prefeeding position.. The self-centering devices 5A, 5B and 5C then lock the bar 2 in place, centering it with the spindle axis. The variable-length bar pusher 4 then moves back to the initial position and the loading device 3 move down, so that the variable-length bar pusher 4 is aligned with the bar 2. The variable- length bar pusher 4 moves forward against to lock the collet 16 onto the bar, the self-centering devices 5A, 5B and 5C are stil locked to prevent the bar 2 from moving. The self-centering devices 5A, 5B and 5C are opened, with the central device 5B set at a diameter 0.30 - 0.50 mm wider than the bar 2. This allows the bar 2 to be mowed forward and rotated freely, while also being well supported. The variable-length bar pusher 4 then moves the bar 2 forward to the bar-stop position and the collet of the spindle locks the bar into place. At this point the lathe can begin the machining cycle, which has been unloaded onto the PLC through HMI 15. When the machining cycle is finished, the lathe unlocks the collet of the spindle and commands the variable-length bar pusher 4 to move the bar 2 forward. When, during the machining cycle, the fixed portion 50 of the variable-length bar pusher 4 is within the reach of the selfcentering device 5B, the self-centering device 5B locks onto it. Pressure is then increased in the rear chamber of the double action pneumatic cylinder 10, in order to extend the mobile portion 51 of the variable-length bar pusher 4 and reach the maximum extension configuration. While the pressure is kept constant, the self-centering device 5B unlocks from variable-length bar pusher 4; from this point, the variable-length bar pusher 4 works in the extended position. The looking sequences of the variable-length bar pusher 4 and the self-centering devices’s are managed by the bar feeder’s PLC according to the lathe’s characteristics and the machining cycle’s parameters. The self-centering devices 5A and 5C are controlled by a pneumatic system or by a rack and pinion mechanism therefore the only position they can be in are: - fully locked , where they will hold both the bar 2 and the variable-length bar pusher 4 in place; - fully open, when they will not make contact with either the bar 2 or the variable-length bar pusher 4. The self-centering device 5B, on the other hand, is controlled by a numerical control electric motor via a worm gear, therefore its position can be controlled in a very accurate and precise way from the HMI 15. The lock timing and the position of the selfcentering devices 5A. 5B and 5C are automatically managed by the bar feeder to provide the most optimal support to the bar 2 and variable-length bar pusher 4 during all working phases. Once the lathe has completed all the machining on the bar 2, the variable-length bar pusher 4 moves backwards, while still holding the remnant with the collet 16 (the remnant is the end portion of bar that cannot be machined). The variable-length bar pushes 4 stops when the moving component 51 and the remnant are within reach of the self-centering devices 5B and 5C, respectively, the selfcentering devices 5B and 5C are switched to the locked position. Air pressure is increased in the front chamber and decreased in the rear chamber of the double acting pneumatic cylinder 10, while the fixed component 50 is moved forward by the electric motor 6 through the transmission system 7. This ensures that the variable-length bar pusher 4 is brought back to the minimum extension configuration (figure 2). After the encoder ha verifies the correct position of the variable-length bar pusher 4, the selfcentering device 5B is unlocked and the variable-length bar pusher 4 is moved back to the initial position. Since the remnant is still locked in place by the self-centering device 5C, it separates from the collet 16 when the variable-length boa pusher 4 reaches the initial position, the self-centering device 5C is unlocked from the remnant, which falls into the remnant recovery area. A new bar is loaded and the whole working cycle starts over. The invention can be susceptible to variations, while maintaining its concept and purpose. The invention can be modified by replacing all components with others to carry out the same function, while still being legally protected by this patent.

Claims

8

CLAIMS.

1 ) Short bar feeder equipped with a storage area (1 ) for at least a bar (2) and a loading device (3) which loads one bar (2) at a time, characterized in that it is equipped with a variable-length bar pusher (4) and three self-centering devices (5A, 5B, 5C), which support both the bar (2) and the variable-length bar pusher (4).

2) Short bar feeder, according to claim 1 , characterized in that the horizontal movement of the variable-length bar pusher (4) is controlled by a numerical control electric motor (6) with transmission system (7).

3) Short bar feeder, according to claims 1 and 2, characterized in that the variable-length bar pusher (4) can change its length by means of a double acting pneumatic cylinder (10), which has a piston (8) connected to a rod (9) all controlled by pneumatic system (11 ).

4) Short bar feeder, according to claims 1 , 2 and 3, characterized in that the numerical control electric motor (6) that drives the variable-length bar pusher (4) is fitted with an encoder (12).

5) Short bar feeder, according to claims 1 , 2, 3 and 4, characterized in that the numerical control electric motor (6) and the encoder (12) are connected to an Arithmetic Logic Unit (13).

6) Short bar feeder, according to claims 1 , 2, 3, 4 and 5, characterized in that the variable-length bar pusher (4) has 9 a fixed component (50) at the rear and a moving component (51 ) at the front and it features a rotating tip (17) on which a collet (16) is fitted in order to securely hold the bar (2).