Installation of sequential loading of bars of material in a machining center

An installation for sequential loading of bars of material in a spindle of a machine for machining the bars, the installation comprising an elongated pusher, wherein the pusher

• has a front end, which is intended to move a first end of the bar, in order to be able to ensure translatory movement of the bar,
• is placed under the control of a first device and capable of ensuring the translatory movement of the pusher in a first direction and a second direction opposite the first direction in such a way as to move the front end, in the first direction, towards the interior of the machine or, in the second direction, towards the interior of the installation and
• in the first direction, bring the front end into contact with the first end of the bar, aligned beforehand with the pusher and ensure a contact with the first end, so that at the latest after the bar has been engaged by a second end through the entrance of a passage that the machine has in the alignment of the spindle and up into a spindle nose of the spindle and at the level of which said bar can be held tightly with a view to allowing the machining of a portion which exceeds the spindle nose,
• also in the first direction, to move sequentially the front end in such a way as to move the bar by a fraction of its length so that the products can be successively machined then taken from the bar,
• in the second direction, to extract from the machine the front end of the pusher in a manner so as to allow, afterwards, a new movement of the front end in the first direction towards a first end of a new bar, preloaded, with a view to a new cycle of operations of loading and of movement of the new bar,
• the pusher comprising at least one first part which has the front end and a second part that is connected to the first device and these two parts, referred to together as sliding parts, are mounted sliding one in the other in such a way as to be mobile, one with respect to the other, along a sliding axis, and this between two states which are
• a first state which, referred to as a state of contraction, corresponds to a state in which one of said sliding parts is retracted in the other, conferring to the pusher a usable length for moving the front end between the entrance of the passage aligned on the spindle and the spindle nose, which is of minimal size, and
• a second state which, referred to as state of extension, corresponds to a state in which one of said sliding parts extends partially outside the other, and this over a distance of extension the value of which is predetermined, conferring to the pusher a usable length of a maximal value,
• this installation, wherein:
• the sliding parts are placed under the control of a second device, which makes it possible to influence the transition of the pusher from the state of contraction to the state of extension, and, reciprocally,
• the first device and the second device are placed under the control of a third device, which allows at least at the start of one of the two operations which are, on the one hand, the operation of loading of the bar into the machine and, on the other hand, and operation of movement of the bar in said machine by a first value necessary to achieve a product, taking into account the effective length of the bar during the operation under consideration and of verification by calculation of whether the usable length of the pusher under consideration in the state of contraction is sufficient to ensure at least one of the two operations consisting of
• moving the bar to bring the second end substantially up into the spindle nose, and
• moving the bar by a fraction of its length which corresponds to the value necessary to achieve a product, and
• if the usable length of the pusher in the state of contraction is of a sufficient value, then maintaining such a state of contraction and, on the contrary, if the usable length is insufficient, then activating the relative translation of the sliding parts of the pusher to obtain the state of extension of the pusher,
• one of the sliding parts bears at least two stops for exercising a function of stopping in translation along the sliding axis, and these stops, one called a contraction stop and the other an extension stop, are disposed with a certain spacing apart to define each one, or respectively the contraction state and the extension state,
• the other sliding part is equipped with an immobilization element intended to co-operate selectively with the contraction stop and the extension stop in such a way as to fix the two sliding parts, one with respect to the other,
• the immobilization element is
• retractable between a first position in which the immobilization element permits the relative sliding of the two sliding parts and a second position in which the immobilization element can co-operate, through a first male part, with one of the two stops which are the contraction stop and the extension stop and thus impede the relative sliding of said sliding parts, and
• connected to an actuation means between, on the one hand, the second position in which the immobilization element co-operates with one of the two stops, which are the contraction stop and the extension stop, to thus impede the relative sliding of the sliding parts and, on the other hand, the first position where the immobilization element is released from any one of said stops to thus allow the sliding of the two sliding parts.