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Technical Field

This invention falls within the technical field of automatic .assembly of electrical and/or electronic components (e.g. transistors, diodes, condensers, resistors, etc.), in a corresponding substrate e.g. a printed circuit board; for this operation it is necessary for the leads of each component to be parallel with each other to permit and facilitate, simultaneous insertion of the leads in the corresponding acceptance holes in the printed circuit board.
This can be achieved with two different configurations; in the first configuration, both the leads are bent perpendicular in relation to the component body; in the second configuration, only one leads is bent, or more precisely, in accordance with two consecutive bends, each at a right angle.
Automatic insertion of the leads of the components in the acceptance of holes of the printed circuit board ceases when the body of the component strikes the front of the printed circuit board, involved in the insertion operation; as regards the other face of the printed circuit board, the leads are to protrude in accordance with predetermined values to optimize the securing and welding phases of the leads to the corresponding conductor track provided for in the said circuit board.
The leads must therefore be cut before insertion in the holes in the printed circuit board. The particular technical sector covering this invention concerns the technical problem just discussed, i.e. cutting the leads.

Background Art

Known cutting devices cause localised deformation and burrs in the cutting zone, forming a stem which is larger than the cross-sectional area occupied by the lead; in other terms, the cross-sectional area corresponding to the cutting zone is greater than the section of the lead, and in addition, varies in value as a function of the tools used for cutting, as well as the actual procedure used for cutting.
In view of the above, manufacturers are obliged to provide holes in printed circuit boards of a dimension which permit free insertion of the ends of leads thus cut with the attendant problems.
A further disadvantage of the known devices is that waste material is formed (fragments, metal powder, etc.) during cutting; this obliges manufacturers to provide means to pick up this waste, as if this falls on the printed circuit board, it is detrimental to mounting components on the printed circuit board.
An object of this invention is to provide a device to cut leads for electrical and/or electronic components in accordance with predetermined geometric profiles, where the cross-sectional area does not exceed the cross-section of the lead concerned.

Disclosure of Invention

The invention provides, in one aspect, a device for cutting leads of electrical and/or electronic components to a predetermined profile, having an operating station S at which gripper mechanisms carried by an intermittently driven conveyor come to rest, the leads of at least one of the said components being clamped by the mechanisms, the leads projecting in the same direction relative to the body of the component concerned (and) in relation to the gripper mechanisms , whereby they are oriented at the operating station S in a predetermined direction characterised in that the device comprises mechanisms to grasp the part of the leads external to the gripper mechanisms, means dependent on activation of the grasping mechanisms to move the mechanisms to apply tension to the leads and phase-related to the activating mechanisms of the gripper mechanisms; upper and lower cutting assemblies heads of which are provided with cutting tools and face the gripper mechanisms (with the latter stationary at the operating station S) and are positioned between the mechanisms and mechanisms the cutting assemblies being so constructed and arranged as to carry out, in the operation of the device, an initial crushing phase in one zone for each lead defining in each zone a predetermined profile, and a second phase of complete cutting of the leads corresponding to this zone.
A preferred device embodying this invention produces components with leads of a predetermined length, following a cutting operation, dependent on the thickness of the printed circuit board concerned.
A preferred device embodying the invention is a multi-component device which can be integrated, with suitable phase-sequencing, with equipment for automatic assembly of leads on a printed circuit board, with a positive effect on the functional performance and reliability of said equipment.
There now follows a detailed description to be read with reference to the accompanying drawings of a cutting device embodying the invention. It will be realised that this device has been selected for description to illustrate the invention by way of example and the the invention, may reside in any novel feature or combination of features described.

Brief Description of Drawings

In the accompanying drawings :- Figure 1. shows a schematic side view, as a section, of a cutting device embodying the invention during the lead cutting phase;
Figure 2. shows a schematic partial view of section I-I in Figure 1;
Figure 3. shows a schematic partial view of section II-II in Figure 1;
Figure 4. shows detail A of Figure 2. magnified;
Figure 5. shows a partial view of section III-III in Figure 4;
Figures 6a, βb show details B, C as per Figures 4 and 5 solely as regards the profile of the lead in the cutting zone, whereas Figure 6c shows the profiles of the lead parts after cutting;
Figures 7a, 7b show a variant of the device in question.

Best Mode for Carrying Out the Invention

With reference to Figures 1 to 6, Figure 1. shows a carousel type conveyor 1, provided alongside gripper mechanisms 2, which comprise pincers with jaws 3a and 3b; the conveyor is motor-driven intermittently, (towards N) , by known components, not shown, so that it stops the gripper mechanisms 2 for a fixed period opposite an operating station S.
The function of gripper 2 is to clamp the leads

10 of electrical and/or electronic components, at a suitable feed station, not shown, the said projecting, in parts 10a, beyond jaws 3a, 3b of gripper 2; this clamping process orientates parts 10a at station S, according to a predetermined spatial positioning.

At station S immediately beside position Ql assumed by the ends of jaws 3a, 3b of gripper 2 at this station, the heads of two cutting assemblies 4, 5, an upper and a lower one respectively, operate.
The upper assembly 4 consists of two tools 6, 7, a first and second respectively; the head of the first tool 6 (feather-edged) is in the form of a comb, hence with teeth 6a and grooves 6b (Figure 5) ; the head of the second tool 7 is likewise in the form of a comb, (hence 0 with teeth 7a and grooves 7b) offset in relation to the comb of the first tool (Figure 5) ; more precisely, the teeth of the one comb fit into the grooves of the other comb and vice versa.
In particular, teeth 7a of the second tool 7 5 extend beyond the grooves 6b of the first tool 6 (see Figure 4) : the advantages of this constructional detail can be seen from the following.
The lower assembly 5 consists of two tools 8, 9, the third and fourth respectively; the head of the third 0 tool 8 faces the head of the first tool 6, and is also in the form of a comb, with teeth and grooves constructed symmetrically, in a horizontal plane, in relation to teeth 6a and grooves 6b of tool 6.
The head of the fourth tool 9, which is facing 5 the head of the second tool 7, is likewise in the form of a comb so that it meshes with the comb of the third tool 8, as described for tools 6, 7.
It can be seen from Figure 4 that as soon as the teeth of the first and third tools 6, 8, are in contact, C as stated below, on the position Ql side, they are sloped to form a seat, or notch, 12, of triangular section; similarly, on the opposite side of this seat 12, the teeth of the third and fourth tools 7, 9 define a seat, or notch, 13, of triangular section.
5 Tools 7, 9 (second and fourth tools) are carried in associated slides 21 (Figure 2) sliding on corresponding faces, or guides, 15, forming two flat parallel faces, constructed on opposite sides at the head of carriage 30; a similar number of metal tubes 16 are provided in the said slides, and the axes of these tubes are perpendicular to the traversing direction of the related guides.
On the metal tubes 16 are bearings 17 keyed .to the outside, sliding inside a cam track 18 constructed in a disc 19 keyed onto a shaft 20.
The other tools 6, 8 (first and third tools) are also carried in a corresponding slide 14, sliding in the direction of slide 21, guided by one side of face 22 (forming a flat parallel surface) and the other side of the aforementioned slide 21, as can be seen in Figure 2; a similar number of pins 23 are secured to slides 14, inserted similarly in the above metal tubes 16, onto which bearings 24 are keyed, sliding in a cam track 25 constructed in the said disc 19 alongside track 18.
The profile of the cam tracks 18 and 25 is such that it moves the corresponding tools 7, 9 and 6 , 8 in both directions Tl, T2; in particular, the said tracks force assemblies 4, 5 respectively to traverse in direction Tl and T2 until they are in contact with the relative heads (1st phase; see Figure 4) ; at this point, track 25 forces tools 6, 8 to halt while track 18 forces slight traversing of tools 7, 9, towards Tl, again with the relative heads in contact as described above (2nd phase) ; traversing of tools 7, 9 towards Tl (with the remaining tools 6, 8 locked) is possible due to play between the metal tubes 16 and pins 23. The shaft 20 is made to rotate by a control shaft 26, by means of known mechanisms 26a, supported radially by carriage 30, an arm 27 being keyed onto the end of this shaft, and this arm being coupled to a tie rod 29, by means of joint 28, which in turn is coupled, by means of joint 31, to the end of a lever arm 32, the other end of which is supported on a fixed structure 33.
The lever arm 32 centrally supports the pin of a small roller 34 sliding in a cam track 35 (indicated partially by a broken line in Figure 1) constructed on the peripheral surface of a drum, not shown, carried by a main shaft 36 (Figure 1) supported radially by the structure 33 and in constant rotation (direction M) via known mechanisms, not shown.
Rotation of the said drum causes oscillation of the arm 32 in a plane normal to the plane of Figure 1; this involves periodic oscillation of the control shaft 26, and hence of cam 19, following direction K_ and K., (Figure 2) .
Carriage 30, and together with this, control shaft 26, are supported by wheels 37 sliding on rails 38 coupled to structure 33; this affords traversing of carriage 30, and together with this, control shaft 26, in directions Fl, F2.
This traversing is achieved by means of a lever

39, supported . at 40 on structure 33; the arm 39a of this lever supports a small roller 41 sliding in a track 42 (shown partially as a broken line) constructed on one side of disc 96, keyed onto the said shaft 36, whilst the remaining arm 39b contains a slot 43 within which a small roller 44 is coupled, supported radially by carriage 30.
On rotation of disc 96 in direction M, lever 39 oscillates in relation to support 40; this moves the carriage 30 between two positions an operative position R (as in Figure 1) an inoperative position I respectively: as regards the latter, only the position assumed by arm 27 and the relative joint 28 are indicated in dash-line (Figure 1) .
It will be seen that between structure 33 and carriage 30, springs 90 are inserted, the function of which is that of 'recovery' of play in roller 44 relative to associated slot 43, in roller 41 relative to associated track 42 (in this way, the roller is constantly maintained in contact with the track) , and finally play in the mechanisms, already shown, which impose oscillating rotation of shaft 20.
At station S, downstream of the cutting assemblies 4, 5 (proceeding from the position Ql) is a gripper 45, the jaws of which 46, 47 are hinged respectively to a small frame 50 supported at 51 on carriage 30; these jaws are, in addition, mutually articulated at 88 as can be seen in Figure 2.
Activation of jaw 46, by means of a jack 48, determines the 'closed' and 'open' position of gripper 45.
Inside jaw 46 there is a striker plate 49 integral with it, facing the other jaw 47.
The said frame 50 is activated by a pneumatic jack 52 which is supported at 53 on carriage 30.
A description will now be given of operation of the above device..
As already stated, the pincer of the gripper mechanism 2 is positioned, by means of a carousel conveyor, locked at station S (at position Ql to be precise) for a predetermined period.
Positioning in S of sections 10a of the leads 10, external to jaws 3a, 3b of gripper mechanism 2, is not obstructed by carriage 30 since the latter is in the inoperative position I; transition from I to R of carriage 30 takes place with both assemblies 4, 5 in the maximum withdrawal position and with gripper 45 in the position shown in Figure 4. but with its jaws 46, 47 in the 'open' position.
At this point, by means of jack 48, the gripper 45 is closed (Figure 4) ; this also causes interaction of plate 49 against parts 10a of the leads which deflect downwards in consequence.

Following the above, jack 52 is deactivated; the frame 50 is acted on by resilient means e.g. the return springs (not shown) incorporated in jack 52; in this way the frame is subject to a moment which tends to make it rotate towards Z; leads 10a, grasped by gripper 45, are subjected to tension which is advantageous as explained below.
In fact, if at this point partial release of jaws 3a, 3b of gripper 2 from leads 10 is effected, component 11 traverses towards E until the relative body 11a (or of bends lib formed in the leads as in the example Figure 5) strikes against predetermined interior striking surfaces 55 constructed in the said jaws 3a, 3b; this affords production, once cutting is complete, of components 11 with leads of predetermined length which optimizes subsequent insertion of the latter in the relative holes in a printed circuit board (not shown) .
Phase-sequenced with the resetting of the maximum clamping pressure exerted by jaws 3a, 3b on leads 10, assemblies 4, 5 move towards each other traversing in the direction Tl, T2 respectively; this mutual approach ceases on contact of the relative heads as shown in Figure 4. (1st phase) . The above-mentioned first phase causes crushing of the zones 60 concerned due to the feather-edge of tools 6, 7, 8, 9, as shown in detail in Figures 6a, 6b.
In particular, in the part of zone 60 on the side of body 11a of the component, a pyramidal profile 61 is formed, whilst on the opposite part (due to the teeth sections 7a of tool 7 projecting in relation to the grooves 6b of tool 6) a profile 62 is formed consisting of a crushed section 62a, with two tongues 62b branching off it, slightly inclined downwards (cf Figures 4 and 6a) .
This initial phase which does not involve the formation of waste material, primarily comprises crushing of zones 60 to create profiles 61, 62, as above; since there is contact with cutting tools, partial detachment of the profiles 61, 62 as above is also possible, at the same time as crushing.
This detachment certainly happens in the 2nd phase in which tools 6, 8 are locked, whilst tools 7, 9 traverse in synchronization in the direction Tl; this completes cutting of zones 60 according to the profiles in Figure 6c, and the cutting operation does not form any waste material, (other than the portion 10c) as will be seen.
The. said cutting operation affords rotation of frame 50 in direction Z until it reaches its end position Zl (Figure 2) ; at this point gripper 45 moves to the 'open' position and the stress imposed by plate 49 on the portion of lead 10c contained between the jaws 46,' 47 facilitates removal of portion 10c of the lead from the operating ends 46a, 47a of the latter; this portion falls within a collecting guide 70 which leads into an appropriate container, not shown.
Mutual withdrawal of the cutting assemblies 4, 5 and traversing of carriage 30 from position R to position

I complete the basic cycle of this device.
On completion of the cycle, the carousel conveyor 1 is again driven to transfer component 11 with the leads 10, cut as above, from station S to another station (not shown) , and at the same time, feed the station S with a new component 11 whose leads 10 are to be cut identically to that described above, by means of a further gripper 2.
As can be seen from the features of this invention, the device concerned can also cut components

11, with leads also set in the same direction, which are parallel to the axis of the body 11a and not normal to the latter as in the previous case.
A variant is provided for as per Figures 7a, 7b to process the leads indicated by 100a, 100b of component

II in Figure 7a.

Opposite station S on the opposite side to the assemblies 4, 5, in relation to position Ql assumed by jaws 3a, 3b at the station S, mechanisms 80 are provided (e.g. punches and counter-punches, or suitable grippers) which deform lead 100b locally (the one projecting least from jaws 3a, 3b) to construct a small tooth 81 above this (more precisely in that part of the lead which is inside the jaws 3a, 3b - see Figure 7a) .
In addition, at station S, downstream of assemblies 4, 5, in place of one single gripper 45 as in the above case, there are two grippers 45a, 45b, a first and a second one respectively, shown schematically (in that they are similar to gripper 45) , one of which grasps the lead 100a, and the other lead 100b.
Both the grippers 45a, 45b are supported by the said frame 50 and are activated by corresponding pneumatic jacks 48a, 48b, controlled in synchronization defining the 'open' and 'closed' positions for the jaws of the said grippers.
The unit formed by the second gripper 45b and associated jack 48b can traverse, in relation to frame 50, in direction E. Activation of a jack 82, which is dependent on grasping of lead 100b by the second gripper 45b, in phase with partial release by jaws 3a, 3b of leads 100a, 100b, causes traversing of the said unit in the direction E, and sets it so that lead 100b is in tension, until the associated 'tooth' 81 strikes against the striker surface 55 on jaws 3a, 3b, of Figure 7b.
In this way once cutting is completed, leads 100a, 100b project from the said head of body 11a of component 11 according to a predetermined value: the advantages below have already been reiterated above.
This device cuts leads according to a pyramidal profile 61, see Figures 6a, 6b, 6c; this profile does not extend beyond the cross-sectional area of the relative lead which, together with the fact that it is pointed, is extremely advantageous for insertion of the leads cut as above (hence with such profiles) in the corresponding holes in a printed circuit board; it has been shown that the above profile is obtained without forming waste material, other than portion 10c.
In addition, this device provides, once cutting is complete, leads of predetermined length in both of the constructional forms considered.
The activating mechanisms of the device are 'on' or Off type: important as regards interface with a microprocessor unit.
This device is universal, i.e. able to cut leads for components 11 independently of the distance between the leads up to a maximum dependent on the physical dimensions of the device; in addition, if the heads of tools 6, 7, 8, 9 are of an appropriate form, it is possible, by means of this device, to achieve pointed ends of a profile other than a pyramidal form.