FR2479740A1 - Adjuster to alter stroke of mechanical press - has slide crank driven and stroke length adjusted by alteration of eccentric pins - Google Patents

Abstract

The adjuster automatically changes the slide stroke in a mechanical press. The slide is connected by one or more cranks to a crankshaft driven by a motor. The change is given by adding or subtracting the eccentric actions. A dog stops rotation of an eccentric either on the crankshaft or the crank. A clutch-brake is fixed to the crankshaft on the flywheel, the clutch forming the connection between them. The outside of the clutch-brake is in an indexing disc with holes corresponding with tooth adjustment of the eccentric and crankshaft.

Description

 The invention relates to the field of mechanical presses with variable stroke, and more particularly an improvement to automatic stroke change devices.

 Devices of this type are already known, in which the automatic stroke change, based on an addition or a subtraction of two eccentricities, is obtained by immobilizing the crankshaft and by engaging a motorized pinion on the eccentric in order to index it by relative to the eccentricity of the crankshaft. The crankshaft, meanwhile, is conventionally connected to the press slide by one or more connecting rods.

 Known devices of this type all have the drawback of being of complex mechanical construction and of being very bulky.

 The object of the invention is to produce a device which, while entering into safe operation, is of simple and rapid mechanical construction in its implementation.

 According to the invention, this result is obtained by proposing an automatic device for changing the stroke of the slide in a mechanical press with variable stroke, of the type in which the slide is connected by one or more connecting rods to a crankshaft driven in rotation. by a motor, the stroke change being obtained by adding or subtracting two eccentricities, device characterized in that it comprises a dog clutch making it possible to immobilize in rotation an eccentric either on the crankshaft or on the connecting rod, the crankshaft thus being able to be indexed in relation to the immobilized eccentric.

 According to a preferred embodiment, the dog clutch immobilizes the eccentric relative to the connecting rod, the stroke change being obtained by rotation of the crankshaft by means of the power control of the device.

The invention will be better understood with the aid of the description below of a preferred embodiment, with reference to the appended drawings in which
FIG. 1 schematically represents a device according to 1 invention on a press with a connecting rod,
- Figure 2 shows schematically an example of race change.

 As shown, the device according to the invention comprises a direct current motor driving in rotation at low speed a crankshaft (1). This crankshaft conventionally comprises an eccentric (6) which itself supports an eccentric (2).

 The eccentric (2) can be engaged or released from a dog clutch (3), said dog clutch being controlled by jacks (4) and returned by springs (5).

 The crankshaft drives in its rotation a connecting rod (7) integral with the press slide and whose maximum stroke determines the stroke of the slide (see Figure 2). The connecting rod (7) has a drive finger (15).

On the run of the eccentric (2) is placed a detector (8).

 The device comprises, in known manner a clutch-brake (11), in itself known integral with the crankshaft (1) and fixed on a flywheel (10) and receives the power control (9) of the device. The flywheel-crankshaft connection is provided by the clutch (11).

 On the external face of, the clutch-brake (11) is positioned a counting disc (12) comprising at its periphery counting holes whose position corresponds to the alignment of the teeth of the eccentric (2) and of the crankshaft (1).

 Opposite the counting disc (12) are arranged two detectors, one of which (13) is a counting authorization detector and the other (14) is a counting detector.

 The operation of the device according to the invention is as follows.

 When the detector (8) detects the maximum eccentricity of the eccentric (2), it gives the simultaneous order to the clutch-brake (11) to stop the crankshaft and to the jacks (4) to clutch by pushing the dog clutch (3) towards the connecting rod (7).

 The dog clutch (3) releases the eccentric (2) of the crankshaft (1) in rotation, makes the eccentric (2) of the connecting rod (7) integral in rotation by means of the finger (15) and deactivates the detector ( 8) which gives the order to the clutch-brake (11) to engage.

 On the counting disc (12) the detector (13) detects the maximum eccentricity of the crankshaft which corresponds to the maximum stroke of the slide, and causes the detector (14) to twist to count.

 The detector (14) having reached its preselected position gives the simultaneous order to the clutch-brake (11) to stop the crankshaft and to the jacks (4) to reverse by putting them to the purge. The dog clutch (3) then returned by the springs (5) again makes the eccentric (2) integral with the crankshaft and releases it from the connecting rod (7).

mm de la bielle.An example of a change of race has been shown in FIG. (2)

mm from the connecting rod.

 A number of organs have not been described in more detail since they emerge from current techniques known to those skilled in the art. In particular the slide, the crankshaft and its bearings.

 For the selection of the stroke1, a control panel advantageously provided with a pre-selection keyboard, making it possible to display a given number of strokes, for example 20 strokes from 30 to 120 mm. A push button with indicator light controls the automatic stroke change. During the stroke change all the machine controls are locked.

 The device of the invention is applicable to all mechanical crankshaft or eccentric wheel presses, whatever the number of connecting rods

Claims (5)

CLAIMS 1. Automatic device for changing the stroke of the ram in a mechanical press with variable stroke, of the type in which the ram is connected by one or more connecting rods to a crankshaft driven in rotation by a motor, the stroke change being obtained by addition or subtraction of two eccentricities, device characterized in that it comprises a dog clutch (3) making it possible to immobilize in rotation an eccentric (2) either on the crankshaft (1) or on the connecting rod (7), the crankshaft thus being able to be indexed in relation to the immobilized eccentric. 2. Device according to claim 1, wherein the dog immobilizes ltexcentriquepar relative to the rod, characterized in that the stroke change is obtained by rotation of the crankshaft (1) through the power control of the device. 3. Device according to any one of claims 1 and 2, comprising a clutch-brake integral with the crankshaft and fixed on a flywheel, the connection between the flywheel and the crankshaft being ensured by said clutch, characterized in that on the face external of the clutch-brake (11) is positioned a counting disc (12) comprising at its periphery counting holes whose position corresponds to the alignment of the teeth of the eccentric (2) and of the crankshaft (1) . 4. Device according to claim 3, characterized in that opposite the counting disc are arranged a detector (13) for counting authorization and a detector (14) for counting. 5. Device according to any one of claims 1 to 4, characterized in that on the travel of the eccentric (12) is placed a detector (8).