Metal deforming – By deflecting successively-presented portions of work during... – By use of deflectors arranged to bend work longitudinally of...
Reexamination Certificate
1999-07-13
2001-02-13
Crane, Daniel C. (Department: 3725)
Metal deforming
By deflecting successively-presented portions of work during...
By use of deflectors arranged to bend work longitudinally of...
C072S173000, C072S172000
Reexamination Certificate
active
06185969
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a machine for bending tubes with a small diameter, and in particular smaller than 10 mm, which are pre-cut and have connection systems at both ends. It also relates to a bending head, which is designed to equip a machine of this type.
BACKGROUND OF THE INVENTION
The bending machines which are used at present in order to bend tubes of this type conventionally comprise a frame, on which there are mounted bending means, which are provided with support surfaces, between which the tube to be bent passes, is clamped and then bent, the bending means being mounted on a bending head, which can pivot around an axis which is coaxial relative to the axis of the bending block. In addition, these bending machines generally comprise a guide rule, which is disposed upstream of the clamping jaw, and optionally a fold-remover component, which is disposed upstream of the bending block. Finally, they comprise means for longitudinal displacement of the tube relative to the frame.
The main disadvantage of these bending machines consists in the fact that they permit bending of the tubes only on a single side, either towards the right or towards the left. Furthermore, the positioning assembly of the clamping jaw, and the assembly for displacement of the rule, require a space which limits the geometry of the finished bent parts.
In order to eliminate the disadvantage relative to the single direction of bending, three main types of bending machines exist at present.
Firstly, a first solution consists of providing the bending machines with a numerically controlled gripper, which is designed to rotate the tube around its axis, in order to change the direction of bending. However, bending machines of this type have a first disadvantage, which is derived from the fact that during changes of the direction of bending, the movements of the tube generate so-called “whip” phenomena, which in particular can detract from the shape of the part produced.
A second solution consists of providing bending machines which are provided with means for entrainment in rotation of the bending head, which can make the latter rotate around the tube. However, at present, this solution is used exclusively with tubes which are packed onto bobbins, and not with tubes which are pre-cut, and which are previously provided with connections. It has been found that putting these connections into place is more complex and takes longer when it is carried out on products which are bent initially.
Finally, a third solution consists of providing bending machines which have a double bending head, which is associated with means for entrainment in rotation and/or in translation, which make it possible to bring the second bending head into the working position. However, this solution leads to production of bending machines which are relatively complex and large, and thus have a high cost price. In addition, the change of direction of bending makes it necessary to displace the bending heads, and this operation requires a relatively long period of time, which detracts from the productivity of the machine.
OBJECT OF THE INVENTION
The object of the present invention is to eliminate all the aforementioned disadvantages of the present bending machines, and its main objective is to provide a machine which has a very simple design, and therefore a relatively low cost price and a small size, thus making it possible to produce at a very fast pace parts which have a complex geometry, which cannot be produced by means of the present machines as previously described, using straight tubes which have a small diameter, are pre-cut, and are provided with connection systems at both ends.
A further object of the invention is to produce at a fast pace parts which comprise coils.
A further object of the invention is to provide at a fast pace parts which comprise sheathed portions.
A further object of the invention is to provide at a fast pace parts which comprise a final, very short, straight end portion.
SUMMARY OF THE INVENTION
For this purpose, the invention relates to a bending machine comprising a frame, on which there is mounted at least one bending head, and means for longitudinal displacement of the tube relative to the frame, according to an axis (X). According to the invention, this bending machine is characterised in that:
the longitudinal displacement means comprise means for grasping the rear end of the tube, and means for entrainment of the grasping means along the longitudinal axis (X);
each bending head comprises:
two forming rollers, each of which has at least one peripheral groove with a semi-circular cross-section, which, in a coupled position of the rollers, is designed to form a guide duct, which has a neck with a diameter which is substantially larger than that of the tube;
means for relative displacement of the forming rollers, which can position the rollers either in their coupled position, or in a so-called opening position, which can permit passage of the tube according to an axis which is perpendicular to the axis (X);
a folding finger which is disposed upstream, and in the vicinity of the forming rollers;
means for displacement of the folding finger according to a circular path which is centred on an axis (Y) at rightangles to the axis (X);
means for displacement in translation of the folding finger according to an axis (Y,) which is parallel to (Y);
guide units for the tube, which are disposed on both sides of the axis (X), such as to come into contact with the tube upstream, and in the vicinity of the forming rollers, the guide units being designed to retract transversely under the effect of a longitudinal force which is exerted by the grasping means.
Firstly, a bending machine of this type is designed in order to permit bending of pre-cut tubes, which are provided with connection systems at both ends. In fact, firstly, the grasping means are designed to assure maintenance of the rear end of the tube, provided with its connection system, and secondly, the possibility of “opening” of the guide rollers makes it possible to pass through the straight pre-cut tube, provided with its connection systems, either manually, or by means of a loading system.
In addition, a bending machine of this type permits production of parts which have complex and varied geometries, since it makes it possible to provide:
bending by forming on the rollers, by displacing the folding finger according to its circular path which is centred on the axis (Y); and
variable radii, which are larger than the radii of the forming rollers, in particular in order to obtain coils, by placing the folding finger in a fixed position along its circular path, and by thrusting the tube by means of means for entrainment in translation of the grasping means. It should also be noted that during bending operations of this type, the guide units of the tube, which are disposed upstream of the rollers, play an essential part, since by maintaining this tube in position, they prevent any deformation of the portion of tube which extends between the grasping means and the rollers. In addition, the retractable nature of these guide units makes it possible to displace the grasping means until the latter come into contact with the rollers, and consequently to carry out bending of virtually the entire length of the tubes.
In addition, it is also essential to note that the fact that the tube is guided inside the grooves of the forming rollers makes it possible to control suitably the ovalisation of the tubes with a small diameter, during operations of bending of the latter.
The bending machine according to the invention also has the advantage that it makes it possible to bend the tubes in both directions very easily, since the only operations to be carried out in order to change the bending consist of combining displacements in translation, and a displacement according to the circular path, of the folding finger. Thus, this bending machine permits very fast paces of folding, and in addition, owing to its simple design (only the folding finger needs to
Crane Daniel C.
Robolix
Young & Thompson
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