US 3889472 A
The apparatus comprises a carriage 3 moved to and fro alternately along a traverse 1 and which has two opposed resilient gudgeon pins 19 and 22. Each end of the traverse 1 carried a jack 33, 331 with the rods 37, 371 of which project inwardly. The carriage carries spindles 27, 271 resiliently mounted and each of which operates extensions 42, 421 of a slide valve of a distributor 34, 341 controlling the operation of the jacks 33, 331. When the spindle 27 comes against the extension 42 the distributor 34 is operated and causes the advance of the piston rod 37 which drives the carriage 3 back. When the latter arrives at the other end of the traverse the jack 331 reverses the drive. The apparatus is particularly applicable for paint spraying on surfaces.
Description (OCR text may contain errors)
United States Patent [191 Guillaud 1 RECIPROCATING APPARATUS  inventor: Michel Guillaud, Grenoble, France  Assignee: Secmer, S.A., lsere, France  Filed: June 18, 1973 [211 App]. No.: 370,639
1 June 17, 1975 3,796,184 3/1973 Howkins 118/323 Primary ExaminerPaul E. Maslousky Attorney, Agent, or Firm--Dowe1l and Dowell 5 7 ABSTRACT The apparatus comprises a carriage 3 moved to and fro alternately along a traverse 1 and which has two opposed resilient gudgeon pins 19 and 22. Each end of the traverse 1 carried a jack 33, 33' with the rods 37, 37 of which project inwardly, The carriage carries spindles 27, 27 resiliently mounted and each of which operates extensions 42, 42 of a slide valve of a distributor 34, 34 controlling the operation of the jacks 33, 33 When the spindle 27 comes against the extension 42 the distributor 34 is operated and causes the advance of the piston rod 37 which drives the carriage 3 back. When the latter arrives at the other end of the traverse the jack 33' reverses the drive. The apparatus is particularly applicable for paint spraying on surfaces.
6 Claims, 5 Drawing Figures /////////////////////////////////////////////n/&
RECIPROCATING APPARATUS The present invention relates to improvements in reciprocating apparatus. that is to say. intended to permit the to and fro displacement of a member along a slide this displacement being effected generally in a transverse manner with regard to the geometrical axis of a machine.
The known devices of the kind in question are generally realized by means of a shaft grooved by at least two contrary helicoidal peripheral grooves and on which is engaged a nut connected to the member which it is desired to displace to and fro along the bar. This latter is actuated by a unidirectional movement of rotation and the nut carries a catch which cooperates with one of the helicoidal grooves of the shaft so that this nut is given a to and fro linear movement. At the end of the bar the catch changes the groove automatically so that its movement is reversed after each traverse.
It can be easily seen that reciprocating apparatus can be obtained by utilising other well known mechanical elements such as chains, belts and the like.
The known reciprocating devices have drawbacks resulting from their complexity or from their high cost price. In any case they comprise electrical contacts which only permit with difficulty their use in an explosive atmosphere.
The improvements which form the subject of the present invention aim at remedying the above mentioned drawbacks and permitting the realization of an anti-deflagrating sliding device which is of simple and economic realization.
The reciprocating device according to the invention of the kind comprising a tool carrying carriage reciprocating to and fro along a slide. characterised in that the aforementioned slide is provided with two percussion mechanisms disposed one at each of its ends and which act in turn on one of two gudgeon pins resiliently and slidably on mounted with the carriage to reverse the direction of travel of the carriage at the extreme position selected for the end of its run in each direction.
According to one preferred embodiment each percussion mechanism is constituted by a compressed air jack controlled by a distributor the control lever of which is operated by a boss resiliently mounted on the carriage. The gudgeon pins of the carriage are preferably disposed co-axially and they are each thrust in the direction of the corresponding jack by means of a single compression spring placed between the gudgeon pins.
The invention will be described with reference to the accompanying drawings by way of example, to permit better understanding of the invention, the features which it has and the advantage which it is capable of providing:
FIG. 1 is a side elevation of an apparatus according to the invention;
FIG. 2 is an enlarged cross section on line II-II (FIG.
FIGS. 3 and 4 are detail elevations to a larger scale showing the operation of the reversing of the direction of the carriage of the apparatus;
FIG. 5 shows diagrammatically to a smaller scale the curve traced by a stylus carried by a carriage on a band running at constant speed at right angles to the direction of movement of the stylus.
There is shown in FIG. I an apparatus according to the invention cooperating with a traverse 1 associated with two vertical uprights resting on the ground on their lower ends 20. The traverse 1 may be placed at any height whatever along the uprights 2 with the aid of means. not shown.
The aforementioned apparatus comprises a carriage 3 travelling to and fro alternately along the traverse l and two direction reversing mechanisms 4, 4'.
The traverse l is made in the form of a U-shaped girder (FIG. 2) the web of which is disposed vertically. Each of the flanges of this traverse carries a rail 5, 5 having in cross-section the form of a rectangle the lower face of which is grooved by a V groove 6, 6'. The two rails 5 and 5' are situated in two vertical planes offset in respect of one another the upper rail 5 being fixed nearer the traverse 1 than the lower rail 5.
The carriage 3 has a general cylindrical shape and it is provided with two arms 7, 7' extending parallel to the rails 5 and 5' with bearings 8 carried by the arms 7, 7' the balls of which engage the grooves 6 and 6' in the rails 5, 5'. The carriage 3 may comprise any tool carrier but in the present example it carries a gun 9 (FIG. 1) projecting therefrom and capable of directing paint or any other product onto a support 10 which passes at right angles to the direction of travel of the traverse l resting on a base 11.
The body 12 of the carriage 2 has an axial bore 13 the geometrical axis of which is arranged parallel to that of the rails 5, 5'. This bore 13 is stepped at each end of the body 12 to constitute two end bores 14 of greater diameter. The bores I3 and 14 thus define two shoulders 15 against each of which is supported an annular washer 16 made of anti-deflecting material and resistant to compression. Each of these washers is held in place by means of a split pin or circlip l8 engaging in a groove 14a of each bore 14. A gudgeon pin 19 engages in the grooves ofa stuffing box I7 and the washer 16 extending to one of the ends of the body 12. The inner part of this gudgeon pin is provided with a peripheral collar 20 and an axial shank 21.
Another gudgeon pin 22 engages in the bores of the stuffing box 17 and the washer 16 located at the end of the body 12 opposite to that which receives the gudgeon pin 19. The gudgeon pin 22 is provided with a peripheral collar 23 arranged inside the bore 13 and integral with a sleeve 24 incorporating an annular ring 25 into which enters the shank 21 of the gudgeon pin 19. Between the collars 20 and 23 and co-axial with the two gudgeon pins 19 and 23 there is mounted a compression spring 26.
The construction is such that the gudgeon pins 19 and 22 project to an equal length from each end of the body 12 of the carriage 3.
The carriage 3 is provided with two cylinders 27 and 27' having the same geometrical axis arranged parallel to that of the bore 13. These two blind cylinders 27 and 27' are open in the same direction respectively as the gudgeon pins 19 and 22, that is to say, in opposite directions. On the inside of each cylinder 27, 27' is mounted a piston 28, 28' integral with a spindle 29, 29' the free end of which is terminated by a boss 30, 30'. Each spindle 29, 29' passes through the open end of the corresponding cylinder through the bore of an appropriate stuffing box 31, 31'. A compression spring 32, 32' is mounted in each cylinder 27, 27' the ends of which are supported against, on the one hand the ends of these cylinders and on the other hand the corresponding piston 28, 28'.
Each ofthe mechanisms 4, 4 is constituted by a jack 33, 33' connected to a distributor 34, 34' (FIG. 1).
The jack 33 (FIGS. 3 and 4) comprises a cylinder 35 in which is axially mounted a piston 36 the rod 37 of which passes out of this cylinder and in the direction of the carriage 3. This jack 33 is of the double action type. that is to say. the compressed air is sent alternately to the front of the piston 36 through the piping 38 to cause this latter to recede and to the rear of this piston by means of the piping 39 to cause it to advance. The distributor 34 to which are connected the pipings 38 and 39 directs the compressed air coming from a piping 40 towards one or other of the aforementioned pipings by means ofa slide valve 41 which has an extension 42 directed in line with the spindle 29 of the carriage 3.
The carriage 3 has a boss 43 (FIG. 1) with its axis parallel to that of the bore 13 of the body 12 and the blind bore of which, not shown. is open in the direction to the right in the FIG. 1. This bore is connected to a source of compressed air by means of a stop valve.
The operation is as follows:
The carriage 3 being in any position between the two mechanisms 4, 4, the valve which controls the arrival of compressed air into the bore of the bore 43 is opened. The air escaping through the opening of this bore displaces the carriage 3 in the direction to the left according to the principle of equality of action and reaction.
When the carriage arrives in the proximity of the mechanism 4 the valve is closed again so that the carriage continues to run by inertia (FIG. 3). At the precise moment when the boss 30 comes into contact with the end of the extension 42 of the valve 41 the end of the gudgeon pin 19 is at such a distance from the free end of the piston rod 37 of the jack 33 that when the slide valve 4] has travelled its whole run, the gudgeon pin 19 and the piston rod 37 are practically in contact. At this moment the compressed air arrives through the piping 39 and the piston 36 of the jack 33 is strongly actuated in the direction to the right (FIG. 4). This impulse is absorbed partly by the spring 26 the residual force serving to give the carriage 3 a movement from left to right. The piston rod 37' of the jack 33' of the mechanism 4 is at this moment retracted due to the fact that air is driven through the piping 38 by movement of the piston 36 to the right in the jack 33 and is directed into the jack 33 so as to cause its piston 36' to retract. When the carriage 3 arrives adjacent to the mechanism 4' the same movements are produced as those described with reference to FIGS. 3 to 4 so that the direction of movement of the carriage is reversed.
A reciprocating device is thus realized the speed of displacement of which is constant over the whole length of its course as follows from the diagram of FIG. 5. In fact each advance and each return of a stylus carried by the carriage 3 and resting on a sheet of paper which passes at constant speed in the direction of the arrow F is a straight line.
It is obvious that the course of the carriage 3 which is particularly precise may be easily regulated by displacing the mechanisms 4, 4' along the traverse l by means, not shown, and the speed of the carriage may be varied by varying the compressed air pressure. Of course the characteristics of the spring 26 are only valid for a certain range of variation of speeds; if the speed increases or decreased beyond the limit of this range the characteristics of this spring must be changed. The speed may moreover be raised to high levels. that is to say, it may reach a value of about three metres per second without any shock being observable at the moment of reversal of the direction of displacement.
One could furthermore if it were necessary reduce the speed of the carriage at the end of the run by fixing the jacks 33, 33' by means of rubber blocks.
It will be noted finally that the springs 32 prevent any deterioration of the distributor 34 or of the spindle 29 in case of any malfunction of the normal working of the change of direction. for example, at the time ofa severe lack of compressed air.
It must furthermore be understood that the preceding description has been given only by way of example and that it in no way limits the scope of the invention.
What I claim is:
1. Apparatus for reciprocating a carriage which is mounted to move freely to and fro between two extreme positions upon a traverse girder. said apparatus comprising:
a. a source of fluid under pressure;
b. on the girder at each of said extreme positions a fluid impulse mechanism operative to deliver thrust to said carriage when it reaches the extreme position to cause it to travel by inertia to the opposite extreme position; and valve means coupled between said source and each impulse mechanism and operative when actuated to deliver fluid pressure to the impulse mechanism;
c. on said carriage arm means located to actuate the valve means when the carriage reaches each of said extreme positions thereby to pressurize the adjacent impulse mechanism, and said carriage com prising a body having a bore extending therethrough and aligned with said fluid impulse mechanism, a pair of axially aligned gudgeon pins extending from both sides of the body and reciprocably captivated in the bore and disposed respectively to receive the thrust from one of said impulse mechanisms, and spring means in the bore urging the pins outwardly thereof, whereby the pins cushion the impact of the impulse mechanisms.
2. Apparatus as set forth in claim I, wherein each of said impulse mechanisms comprises a jack having a piston member extended in the direction of the carriage when the jack is pressurized.
3. Apparatus as set forth in claim 2, wherein each jack comprises a double acting fluid pressure piston, each valve means being connected to enter fluid pressure into a space behind the piston of the corresponding jack to advance it toward the carriage, and the jacks having fluid spaces in front of their pistons which spaces are mutually connected together so that one piston is retracted when the other is advanced.
4. Apparatus as set forth in claim 1, wherein said arm means on the carriage comprise oppositely facing spindles located to abut a valve means when the carriage reaches an extreme position and thereby actuate it to pressurize the corresponding impulse mechanism.
5. Apparatus as set forth in claim 4, wherein each of said spindles is reciprocably mounted in a bore in the carriage and spring loaded to urge it in the direction of the valve means which it must actuate.
6. Apparatus as set forth in claim 1, including a compressed air nozzle on the carriage and facing in one direction of travel thereof and pressurizable to displace the carriage toward the opposite impulse mechanism to initially start the movement thereof.