FR3121622A1 - HEAD FOR GRIPPING AND PUNCHING A PART ALLOWING ITS DRIVE IN ROTATION FOR ITS MACHINING - Google Patents

Abstract

The present invention relates to a head (20) for gripping, clamping and punching a workpiece which comprises a structural frame (22) of generally vertical orientation which carries a lower die (38), a stripper ( 102) upper and a punch carrier, and an actuating cylinder (52) whose rod is connected to the punch carrier characterized in that the stripper (102) is axially movably mounted on the punch carrier (84) between a lower position towards which it is elastically returned and an upper position, so that the control of the cylinder (52) successively causes the clamping of the part, then its punching, and in that the head (20) comprises a motorized unit of rotary drive of the punch holder (84). Figure for abstract: 3

Description

HEAD FOR GRIPPING AND PUNCHING A PART ALLOWING ITS DRIVE IN ROTATION FOR ITS MACHINING

Technical field of the invention

The present invention relates to a head for gripping, clamping and punching a part, in particular a thin and flat part and for example a cover, which it is desired to be able to machine - in particular grind, deburr and/or cut - by rotating this part.

The invention relates in particular to a gripping and punching head capable of being carried by a robot arm.

The invention relates in particular to the machining of parts of simple or complex shape and for example the machining of parts whose general shape of the periphery can be circular or oval and/or of complex geometry.

Technical background

In general, a punching machine comprises a frame which carries a counter-support die opposite which a stripper moves axially and a punch holder which carries a central punch coaxial with the stripper.

It is known from document FR2487703 to use hydraulic means arranged between the stripper and the punch holder to control the movement in sequence of the stripper, then of the punch.

The weight of such a design does not allow it to be adapted to constitute a gripping and punching head capable of being carried by a robot arm.

In addition, it appeared necessary to be able to drive a previously punched part in rotation when it is desired to carry out machining operations on this part, in particular at its periphery.

Performing such machining operations by resuming the previously punched part on a punching machine is possible and can be automated, but such solutions are costly in terms of time and investment.

In addition, the adaptation of the recovery and machining operations is particularly complex due to the general shape of the periphery which can be of simple shape, for example circular or oval and/or of complex geometry.

In order to solve all or part of these problems, the invention proposes a head for gripping, clamping and punching a workpiece which comprises a structural frame of generally vertical orientation which carries:
- a lower matrix;
- an upper stripper for clamping the part and a punch holder which are mounted movably, axially in the vertical direction, facing the lower die;
- an actuating cylinder whose output rod is connected to the punch carrier to drive it axially between a high rest position and a low punching position;
characterized:
-- in that the stripper is axially movably mounted on the punch holder between a lower position towards which it is elastically returned, and an upper position, so that, from the upper rest position of the punch holder, the control of the actuating cylinder successively causes the clamping of the part, then its punching;
-- and in that the head comprises a motorized unit for driving the punch holder in rotation to drive the stripper, and a part clamped axially by the stripper, in rotation about an axis of rotation parallel to the axis of clamping, and the lower die is rotatably mounted relative to the structural frame about said axis of rotation.

According to other characteristics of the invention:
- The stripper is guided axially with respect to the punch carrier, and at least one axially acting return spring is interposed between the punch carrier and the stripper;
- the head comprises a movable support which is mounted to slide vertically with respect to the structural frame, which is moved in both directions by the rod of the actuating cylinder, and on which the punch holder and the motorized unit are mounted rotary drive of the punch holder;
- the punch holder is mounted for rotation relative to the mobile support, and the motorized unit for driving the punch holder in rotation comprises a motor which drives the punch holder in rotation;
- the motor comprises an output shaft which is parallel to the axis of rotation of the punch holder and drives it in rotation by means of a belt or a transmission chain which extends in a horizontal plane;
- the structural frame is C-shaped and comprises a horizontal lower branch which carries the lower matrix, a horizontal upper branch on which the support is slidably mounted, and a vertical branch connecting the two horizontal branches;
- a free end of the horizontal upper branch carries a sliding guide block for the mobile support and for fixing the actuating jack
- the output rod of the actuator cylinder extends axially in the vertical direction and, at its lower end, is connected to the punch holder to drive it axially;
- the vertical branch carries a plate for fixing the head to a manipulation arm, in particular to an arm of a robot

Brief descriptions of figures

Other characteristics and advantages of the invention will appear during the reading of the detailed description which will follow for the understanding of which reference will be made to the appended drawings in which:

- the is a general perspective view of an embodiment of a head according to the invention which is shown with the punch holder and the stripper in the high vertical position of rest;

- the is a half-view in perspective according to another angle of view and in section through the median vertical and longitudinal plane of the head shown in , and on which the actuator is not shown;

- the is a perspective view of a first sub-assembly made up of the main fixed components of the head illustrated in FIGS. 1 and 2;

- the is a perspective view of a second sub-assembly made up of the main moving components of the head illustrated in FIGS. 1 and 2 which constitutes a module or assembly which is mounted to move relative to the first sub-assembly;

- the is a partial perspective view from below of the head shown in Figures 1 and 2;

- the is a side view of the head shown in Figures 1 and 2;

- the is a view analogous to that of on which the punch holder is shown in an intermediate vertical position in which the stripper is in the clamping position of a lid to be punched;

- the is a partial sectional view through the median vertical and longitudinal plane and on a larger scale of the ;

- the is a view analogous to that of on which the punch holder is shown in the low vertical punching position;

- the is a perspective view illustrating the implementation of the head according to the invention for driving in rotation and machining the contour of a previously tightened and punched cover;

- the is a perspective detail which illustrates on a large scale the set of three elastic return springs of the stripper in relation to the punch holder.

Detailed description of the invention

For the description of the invention and the understanding of the claims, the vertical, longitudinal and transverse orientations according to the reference V, L, T indicated in the figures whose longitudinal axes L and transverse T extend in a horizontal plane.

By convention, the longitudinal axis L is oriented from the back to the front.

In the following description, identical, similar or analogous elements will be designated by the same reference numerals.

Example of realization
There is shown in the figures a gripping head 20, also called gripper.

The gripping head 20 here has a general design symmetry with respect to its median vertical and longitudinal plane.

The head 20 comprises a rigid structural frame 22 in the general form of "C".

The frame 22 here consists of two identical and parallel vertical plates 24, each of which comprises a lower longitudinal horizontal branch 26 and an upper longitudinal horizontal branch 28.

At their rear longitudinal ends, the two horizontal branches 26 and 28 are interconnected by a vertical rear panel 30.

The two vertical plates 24 are here connected together, according to a screwed assembly, by:
- A horizontal lower plate 32 arranged between the front end sections of the lower branches 26;
- A rear vertical plate 34 arranged substantially at mid-height between the parallel vertical branches 30; and
- a front vertical plate 36 arranged between the front end edges of the upper branches 28.

Thanks to such a design, the structural frame 22 is in the form of a C-structure which is generally hollow and of great rigidity.

The structural frame 22 thus notably delimits an internal free space or volume 23.

The lower plate 32 carries a matrix 38 of counter-support which here is of generally cylindrical shape and which, by means of a mount 40 with bearings is mounted freely in rotation on the lower plate 32, around a vertical axis. A1.

The rear vertical plate 34 carries a mounting 42 for adjustable and orientable fixing of the structural frame, and therefore of the head 20, for example on an arm of a robot (not shown).

The front vertical plate 36 carries a guide block 44 which is fixed by screwing on its front vertical face 33.

The guide block 44 here comprises two vertical uprights 46 interconnected by a horizontal upright 48 and each of which comprises an emerging vertical bore 50, each of which constitutes a guide slide.

The horizontal upright 48 carries on its upper face a vertical actuator 52.

The jack 52 can be an oleopneumatic jack, or else a hydraulic or pneumatic jack, or else an electric one.

The actuating cylinder 52 comprises an output rod (not visible in the figures) which extends axially downwards through a central opening hole 54 of the horizontal upright 48 of the guide block 44.

The structural frame 22, the guide block 44 and the actuating cylinder 52 constitute a fixed sub-assembly for guiding and driving the mobile sub-assembly 60 shown in particular in .

As can be seen in particular in the , the sub-assembly or movable assembly 60 comprises a movable support 62 which is mounted to slide vertically with respect to the guide block 44 carried by the structural frame 22 and which is moved in both directions by the rod of the actuating cylinder 52.

The mobile support 62 comprises a rear horizontal plate 66 and a front transverse vertical plate 68 interconnected by lateral brackets 71.

The rear horizontal plate 66 has a central cutout and, on its upper face 65, it carries an electric gear motor 70 whose lower output shaft 72 extends axially, along a vertical axis A2 of rotation, below its face. lower 63.

The front vertical and transverse plate 68 carries two vertical guide columns 74, each of which is slidably received in an associated bore 50 of the guide block 44.

At their lower ends, the guide columns 74 are fixed to a connecting block 76 which is thus mounted to move vertically in both directions with respect to the fixed sub-assembly, and in particular with respect to the horizontal lower plate 32 and to the rotating die. 38.

For training in vertical movement in both directions of the mobile assembly 60, the rod of the actuating cylinder 52 is connected to a spacer 78 fixed to the upper face of the connecting block 76.

Beneath its underside 77, the connecting block 76 carries a housing 80 which is closed by a lower washer 82 and inside which a punch holder 84 is mounted for free rotation, around an axis of rotation coinciding with the axis A1, via bearings 86.

The punch holder 84 comprises an upper part 88 which is guided in rotation in the housing 80 and a lower part 90 whose periphery constitutes a ring gear 92 for driving the punch holder 84 in rotation around the axis A1.

For this rotational drive, the head 20 here comprises a toothed belt 94 which is itself driven in both directions by a toothed pinion 96 carried by the lower output shaft 72 of the geared motor 70.

Thus, the motor is an electric motor whose rotor shaft is parallel to the axis A1 of rotation of the punch holder 84 and drives it in rotation via a toothed belt 94, or a transmission chain which extends in a horizontal plane.

The punch holder 84 houses a punch 100 comprising an active lower free end section 101.

The punch 100 is linked axially to the punch carrier and therefore to the connecting block 76 which, under the action of the actuating cylinder 52, drives the punch carrier 84 and the punch 100 in axial displacement in both directions according to the vertical axis A1.

The punch carrier 84 also carries a stripper 102, also called a blank holder, which – in a known manner – is capable of cooperating with the counter-support die 38 to axially clamp a part P to be punched.

The stripper 102 is here a tubular part whose central axial bore 104 allows the coaxial passage of the punch 100 and the axial displacement of the latter relative to the stripper 102.

In addition to its central bore 104, the body of the stripper 102 comprises three guide bores 106 distributed angularly at one hundred and twenty degrees around the axis A1.

The stripper is carried by a mount 108 which also has three bores 110 aligned with the guide bores 106.

For the axial displacement guidance of the stripper 102 relative to the punch holder 84, the latter carries three screwed axial rods 112 for guiding which extend axially downwards below the lower part 90.

Each lower end head 114 of a guide rod 112 is received and slidably guided in an associated guide bore 106 of the stripper 102.

Each lower end head 114 also defines the extreme lower position of the stripper 102 with respect to the punch holder 84.

The stripper 102 is permanently elastically returned to this extreme lower position, here without limitation by three gas springs 116.

The extreme upper position of the stripper relative to the punch holder 84 (shown in ) corresponds to the abutment of the upper face 109 of the frame 108 of the stripper against the countersink 91 facing each other formed in the lower face 90 of the punch holder 84.

Each gas spring 116 is fixed inside a complementary housing 117 of the upper part 88 of the punch holder 84 and it comprises a piston rod 118 which is permanently in elastic support against a head 120 of a screw associated 122 for assembling the frame 108 and the stripper 102.

To press on the upper face of a part P to be clamped axially before its punching, the lower face of the stripper 102 here comprises a flat peripheral annular edge 103 for clamping, while the upper face of the counter-support die 38 is curved and convex and delimits a circular upper central edge 39 of smaller diameter and centered with respect to the annular clamping edge 103.

Centrally, the counter-support die 38 comprises a central steel core 37 for guiding the punch 100 after the latter has passed through the part P.

In the position illustrated in , the actuating cylinder 52 is in its rest state and the punch holder is in the high rest position with a maximum vertical distance between the stripper 102 and the counter-support die 38.

The head 20 thus has a large clearance opening making it possible to process parts of a wide variety of sizes and thicknesses.

Starting from the position illustrated in Figures 5 and 6, to pick up a part P such as a lid here, the robot positions the head 20 with respect to the part P to be picked up. This positioning can for example be carried out by means of a vision device which takes into account the various parameters of dimensions and shape of the part.

Then, the actuating cylinder 52 is activated to cause rapid movement of the punch holder 84 and of the stripper 102 in order to clamp the part P by clamping it axially between the edge 103 and the edge 39, as illustrated in FIGS. 7 and 8.

Thus clamped, part P can then be moved by the robot without risk of this part P falling.

The ram then continues its stroke in order to centrally punch part P as shown in thanks to the additional axial displacement of the punch holder 84 relative to the part P and therefore relative to the stripper 102.

Part P is thus punched and is still clamped by head 20.

The quality of the axial clamping of the part P and its punching avoids any risk of slippage and plastic deformation during machining such as peripheral grinding.

It is then possible to move the head 20 and the part P with respect to a machining tool which is for example a deburring wheel M as illustrated in .

In order to be able to machine the entire peripheral edge of the part P, the latter is driven in rotation by the stripper 102 which is itself driven in rotation by the toothed belt 94.

It is possible to machine a circular or non-circular and for example oval edge or contour by using the ability to control longitudinal displacements of the head 20 with respect to the part.

The geared motor 70 constitutes a seventh servo axis of a six-axis robot equipped with the head 20.

A robot equipped with the head according to the invention can present the part in front of a rotating machining tool and set the part in rotation in order to machine its contour. The gripping head follows the profile of the part during rotation by a servo-controlled translation movement given by the robot

The design thus allows monitoring of the profile of the part during machining for parts that are not round with:
- a reduced servo response time which allows a good correlation between the trajectories followed by the robot, the profile of the part and the machining tool;
- high precision of the servo-control in relation to the profile of the part.

The design according to the invention thus makes it possible to propose a method for machining the peripheral edge of a clamped and punched part P by means of a head 20 according to the invention which also drives it in rotation, the gripping head being carried by an arm of a robot, the paths of movement of the robot and the rotational drive of the part being controlled, in particular to allow the machining of parts of simple or complex shape and for example the machining of parts whose general shape of the periphery can be circular or oval and/or of complex geometry.

Claims (9)

Head (20) for gripping, clamping and punching a workpiece (P) which comprises a structural frame (22) of generally vertical orientation which carries:
- a lower die (38);
- an upper stripper (102) for clamping the part (P) and a punch holder (84) which are movably mounted, axially in the vertical direction, facing the lower die (38);
- an actuating cylinder (52) whose output rod is connected to the punch carrier (84) to drive it axially (A1) between a high rest position and a low punching position,
characterized:
-- in that the stripper (102) is axially movably mounted on the punch holder (84) between a lower position towards which it is elastically returned, and an upper position, so that, from the upper position of rest of the punch carrier (84), the control of the actuating cylinder (52) successively causes the clamping of the part (P), then its punching,
-- and in that the head (20) comprises a motorized unit (70) for driving the punch holder (84) in rotation to drive the stripper (102), and a part (P) clamped axially by the stripper ( 102), in rotation about an axis of rotation parallel to the axis (A1) of clamping, and the lower die (38) is rotatably mounted relative to the structural frame (22) about said axis of rotation. Head (20) according to Claim 1, characterized in that the stripper (102) is guided axially with respect to the punch holder (84), and in that at least one axially acting return spring (116) is interposed between the punch holder (84) and the stripper (102). Clamping head (20) according to any one of the preceding claims, characterized in that it comprises a mobile support which is mounted so as to slide vertically with respect to the structural frame (22), which is driven in displacement in both directions by the rod of the actuating jack (52), and on which are mounted the punch carrier (84) and the motorized unit (70) for driving the punch carrier in rotation. Head (20) according to Claim 3, characterized in that the punch carrier (84) is mounted for rotation relative to the mobile support, and in that the motorized unit (70) for driving the punch carrier in rotation (84) includes a motor which drives the punch holder (84) in rotation. Head (20) according to the preceding claim, characterized in that the motor comprises an output shaft which is parallel to the axis (A1) of rotation of the punch holder (84) and drives it in rotation by means of a transmission belt (94) or chain which extends in a horizontal plane. Head (20) according to one of Claims 4 or 5, characterized in that the structural frame (22) is C-shaped and comprises a horizontal lower branch (26) which carries the lower die (38), an upper horizontal (28) on which the support is slidably mounted, and a vertical branch (30) connecting the two horizontal branches (26, 28). Head (20) according to Claim 6, characterized in that a free end of the horizontal upper branch (28) carries a block (44) for guiding the mobile support in sliding and fixing the actuator (52). Head (20) according to the preceding claim, characterized in that the output rod of the actuating cylinder (52) extends axially in the vertical direction and, at its lower end, is connected to the punch holder (84) to drive it axially. Head (20) according to Claim 7, characterized in that the said vertical branch carries a plate (36) for fixing the head (20) to a manipulation arm, in particular to an arm of a robot.