EP0095246A1

EP0095246A1 - Linear control device

Info

Publication number: EP0095246A1
Application number: EP83302232A
Authority: EP
Inventors: Leonard William Norton Jones
Original assignee: James Burn Bindings Ltd
Current assignee: James Burn Bindings Ltd
Priority date: 1982-05-21
Filing date: 1983-04-19
Publication date: 1983-11-30
Also published as: GB8310502D0; GB2120813A

Abstract

A linear control device suitable for a wire binding machine in which a piston (10) which is arranged to move a component such as a closing tool (14) is controlled between several positions by means of a switch or switches (30, 32). The switch or switches control the position of the piston (10). The switch or switches can be moves by means of a controller (52) so that when the piston reaches a switch position a fluid controller (53) shuts off a supply of pressure fluid to a cylinder (28) in which the piston (10) is mounted. The switch or switches are operated by the piston by magnetism.

Description

The present invention relates to linear control devices suitable for wire binding machines for closing wire binding elements to bind bundles of sheets.
In certain operations of such machines relative linear motion is required between components, the stroke being carefully controlled between several linear positions. Hitherto this action has been provided by coupling several pneumatic cylinders together in tandem and using the full stroke of each cylinder to move from say A to B then the next cylinder's full stroke to move from B to C and so on. This arrangement is somewhat cumbersome and expensive in terms of provision of the several cylinders and corelated control gear.
A linear control device according to the present invention comprises a cylinder, a piston operable within the cylinder, the piston or an attachment thereto being magnetised, at least one magnetically operable switch adjustably mounted along the cylinder, the adjustment of the or each switch mountings being relatively parallel to the direction of movement of the piston, the switch(es) being operatively connected to control means so that when the piston or magnetic element thereon reaches a said switch position, the control device stops the flow of fluid moving the piston, whereby the piston is stopped at that switch position.
The control device of the invention enables a single cylinder to be stopped accurately at a predetermined position intermediate the top and bottom of the piston stroke so that only a single cylinder need be used.
Preferably the switches are moved on threaded shafts by motors driving the shafts, the motors being controlled to run between adjustable limits.
Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows a closing cylinder for a binding machine controlled according to a first embodiment and
Figure 2 shows a similar but modified arrangement to Figure 1 according to a second embodiment.

In Figure 1 a cylinder 28 has a magnetised piston 10 attached to a piston rod 26 which moves through two arms 20, 22 of a lever 18 a link 16 to move a closing tool 14 upwards and downwards.
Movable upwards and downwards parallel to the piston rod are two reed switches 30, 32. The switches are mounted on threaded shafts 34 and 36 respectively, each shaft being driven by a respective motor 38 and 40.
The reed switches each operate when the magnetised piston is adjacent the switch.
The position of the reed switches are each controlled via knobs 50 and 51 via known servo control arrangements in an electrical controller 52 so that an indication at particular points of the piston stroke is given to the electrical controller 52. As soon as the position indication is received by the controller 52 a solenoid operated spool valve in the pneumatic controller 53 closes the supply of pressure fluid to the cylinder 28 and the piston stops. At the same time a signal is sent to programme control "Biselector" 54 the operation of which is described in our co-pending British Patent Application No. 8111827 filed 14th April 1981. The Biselector 54 then "knows" the tool 14 has reached a certain position and can then step on to the next stage of the programme. A signal is then sent from the Biselector when it reaches its next stage to the controller 52, the shuttle valve is then operated to allow pressure fluid to enter the cylinder. The piston 10 then moves to the next reed switch position and so on to the top of its stroke.
In Figure 2 showing a second embodiment and in which similar components to Figure 1 are similarly numbered the two arms 20 and 22 of Figure 1 are replaced by a single rocker arm 19 connected to the closing tool 14' through a turnbuckle 17 which allows for adjustment between the piston 10 and the closing tool 14'. The Biselector programme control 54 is replaced by an equivalent pneumatic sequencing programme controller 54'. The motors 40' and 38' are electrically controlled by pairs of switches 50', 50" and 51', 51" on a control board so that the reed switches 30 and 32 can be moved up or down to visually set positions for the stroke of the piston. The visual settifig is by observation of the position of the closing tool 14'.
The fluid control 53 in both embodiments is a simple shuttle valve movable from a position in which fluid is supplied to the top of the piston, to a second position in which no fluid is supplied to the cylinder 28' and to a third position in which fluid is supplied to the bottom of the piston. The control of the shuttle valve is by known electro/pneumatic servo arrangements.
It will be appreciated that the linear control device of the invention can be used to control any linear or even with suitable linkage part rotary movement involving stopping the piston motion at any position or positions intermediate the top and bottom of the piston stroke.

Claims

1. A linear control device comprising a cylinder , a piston operable within the cylinder, the piston or an attachment thereto being magnetised, at least one magnetically operable switch (30,32) adjustably mounted along the cylinder, the adjustment of the or each switch mountings being relatively parallel to the direction of movement of the piston, the switch(es) being operatively connected to control means (52) so that when the piston or magnetic element thereon reaches a said switch position, the control device stops the flow of fluid moving the piston, whereby the piston is stopped at that switch position.

2. A device as claimed in Claim 1 wherein the or each switch (30,32) is mounted on a threaded shaft (34, 36) which is arranged to be rotated by a motor (38, 40) controlled by the control means.

3. A device as claimed in Claim 1 or 2 wherein two motors (38, 40) are provided each controlling the movements of its magnetically operable switch so that the piston can be controlled to move between two positions set by the positions of the switches.

4. A device as claimed in Claim 2 wherein the controller is provided with a pair of switches (50', 50") controlling the movement of one motor driven switch (30, 32) in a direction towards one end or the other of the stroke of the piston.

5. A wire binding machine having the linear control device of any of Claims 1 to 4 in which the piston is connected operatively to a closing tool.

6. A machine as claimed in Claim 5 wherein between the closing tool and piston an adjustment (17) is provided for adjusting the position of the closing tool relative to the piston.