CH673246A5 - - Google Patents

Description

DESCRIPTION

A scroll saw consists of a blade stretched between the branches of a U-shaped frame to which a handle is rigidly attached. With such a tool, the possibilities of cutting into a large room are limited. We are quickly stopped by the collision of the frame against the edge of the part as soon as the saw cut describes a curve. Cutting along a closed line is impossible.

The use of cylindrical blades does not improve the tool much: the saw line is wide, the very acute angles impossible. The saw according to German patent 26 37 145 has a laterally foldable rear part. This tool retains its shape during cutting work. Cutting into a closed curve is impossible.

To remedy these drawbacks, the present invention, defined in claim 1, proposes a scroll saw whose blade can pivot on its longitudinal axis. Controlled for example by the saw handle, or by means of a wheel, this blade can be oriented during cutting, independently of the carrying frame.

We therefore see that this saw makes it possible to follow any cutting line - even closed - even in a large room.

The blade of this saw can pivot with its tenons, these extend in the form of rotation shafts. They are mounted coaxially with the blade in perforations in the arms of the frame. For this saw to work satisfactorily, it is imperative that the blade behaves in its rotation like a rigid part. The rotational movements of its two studs are therefore synchronized, as defined in claim 2, by a device whose organs run along the frame of the saw, this in order to leave the field delimited by the frame and the blade free for the movements of chopped off.

The first embodiment has a device for synchronizing the tenons of an endless belt blade, as defined in claims 9 and 10.

The second embodiment has a synchronization device with sheathed cables and bevel gears according to claim 8.

The third embodiment has a synchronization device produced by means of three shafts provided with bevel gears at their ends. It is defined in claim 7. Embodiments of this saw are described, by way of example, with reference to the accompanying drawings.

Figure 1 is a partial sectional view of the first embodiment showing the end of the upper arm of the saw frame.

Figure 2 is a sectional view.

Figures 3 to 7 are sectional views respectively along lines A A ', D D', C C ', B B' and L L'of Figure 1.

Figure 8 is a partial sectional view of the first embodiment showing the end of the lower arm of the saw frame.

FIG. 9 is a plan view of the pulley of FIG. 8.

FIGS. 10 and 11 are sectional views respectively along lines E E 'and M M' of FIG. 8.

Figure 12 is a partial sectional view of the rear part of the saw frame, according to the first embodiment.

FIG. 13 is a rear view of the part of the saw shown in FIG. 12.

FIG. 14 is a sectional view along line Q Q 'of FIG. 13.

Figures 15,16 and 17 are elevational views of the second embodiment.

The saw shown in Figures 1 to 14 comprises a toothed blade mounted at the ends of the arms 10 and 20 of a U-shaped frame.

The upper arm 10 (FIG. 1) of the latter carries a shaft 1 secured to a blade tenon 6. This shaft, pivoting in a bearing 5, is secured to a pulley 4.

The lower arm 20 (FIG. 8) to which is fixed a handle-carrying tube 21 holds a pin-holding shaft 23 dependent on a pulley 27. The shaft 23 pivots in the bearings 24 and 25, while the handle 22 s' presses on a bearing 26 for the rotation, and the bearing 24 for the thrust from bottom to top.

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The pulleys 4 and 27 are made integral by means of an endless belt. This, carried by the rollers 31, 32, 33 and 34 (Figure 13) runs along the frame of the saw. Its two strands, leading and led, are crossed so that the pulleys 4 and 27 rotate in the same direction.

Thus, a rotation of the handle 22 by an alpha angle forces the two pulleys 27 and 4 to also rotate by this same alpha angle, which drives the entire blade.

The belt tension is adjusted by a sliding part 9 which can slide along the upper arm 10 and carries two rollers 12 and 13 with a vertical axis. The two strands of the belt are supported on these rollers 12 and 13, passing through the gap between them. This interval being less than the diameter of the pulley 4, the rollers bring the two strands of belt together. By moving the part 9 towards the pulley 4, the total path of the belt is lengthened. The part 9 thus plays the role of tensor. This tensor 9 can be fixed in the appropriate position by means of a tightening screw 11. The spacing of the rollers 12 and 13 carried by the tensor 9 is such that it corresponds to the distance between the rollers located at the posterior angles of the saw frame, 31-32 and 33-34.

The lower arm 20 (FIG. 8) also carries a pair of rollers 20 30 with vertical shafts located some distance from the pulley 27. The shafts on which they pivot are fixed. Their spacing is identical to that of the rollers of the upper arm. In this first embodiment, the play of the parts in operation must be practically zero to avoid twisting of the blade. 25

The second embodiment differs from the first by the device for synchronizing the blade tenons. It is shown in Figures 15, 16 and 17.

Synchronization is achieved by the use of sheathed cables 35 which connect the upper and lower blade tenons by means of bevel gears.

The handle is rigidly fixed to the frame of the saw and controls its orientation.

The orientation of the blade - the angle it makes with the plane of the frame - is controlled by a wheel 37 which is actuated by the fingers of the hand carrying the tool. The synchronization device has a median element constituted by the gear 38 to which the rotation of the dial 37 is transmitted by means of the sheathed cable 36. From this midpoint, the controlled angle of rotation is symmetrically retransmitted by the sheathed cables 35 to the drive sprockets for the blade tenons.

The advantage of this device consists in making the mechanical play of the moving parts inoperative with respect to the torsion of the blade.

The position of the handle on the frame is set back relative to the blade, and the saw has a support 39 set back from the handle. This support allows the operator to let the tool rest on the hand that grips the handle, between the roots of the thumb and forefinger.

According to the third embodiment not shown, the sheathed cables are replaced by three shafts provided with bevel gears at their ends.

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3 sheets of drawings

Claims (12)

673,246 CLAIMS 1. Scroll saw, characterized in that its blade is arranged so as to be able to pivot without twisting with its two tenons on its longitudinal axis, in such a way that the direction of the saw cut can be oriented during the work of the saw independently the orientation of the frame. 2. Scroll saw according to claim 1, characterized in that the rotational movements of the blade tenons are made interdependent and synchronized by a device whose organs are arranged along the frame of the saw. 3. Scroll saw according to claims 1 and 2, characterized in that the device for synchronizing the blade tenons has a central element such that it divides this synchronization device into two symmetrical parts. 4. Scroll saw according to claims 1 to 3, characterized in that it comprises a member for driving the blade transmitting the rotational movement to the device for synchronizing the tenons at its point or to its median element, by a member for transmission, so that the subsequent transmission of this rotation from this point or this element to the two blade tenons is done symmetrically. 5. Scroll saw according to claims 1 to 4, characterized in that the control member of the blade direction consists of a handle which can pivot on its longitudinal axis. 6. Scroll saw according to claims 1 to 4, characterized in that it comprises a wheel mounted near or on a handle so that, to orient the blade, this wheel can be rotated by the fingers of the hand holding the handle, and in that this handle is fixed on the frame. 7. Scroll saw according to claims 1 to 4, characterized in that the device for synchronizing the blade tenons consists of three transmission shafts provided with conical toothed wheels which interconnect two toothed wheels each of one of the let's hold on. 8. Scroll saw according to claims 1 to 4, characterized in that the blade tenon synchronization device consists of a sheathed cable which, by pivoting in its sheath, connects the two tenons by bevel or screw gears unending. 9. Scroll saw according to claims 1 to 4, characterized in that its synchronization device consists of two pulleys coaxial with the blade, each secured to one of the tenons, and connected together by an endless belt with strands crossed which rests on driving rollers mounted on the frame along the path of this belt. 10. Scroll saw according to claims 1 to 4 and 9, characterized in that it is provided with a belt tensioner consisting of a piece sliding along one of the arms of the frame, which carries two rollers on rotation shafts parallel to the blade which bring the two strands of the belt together so that a displacement of this sliding part towards the pulley lengthens the path of the belt. 11. Scroll saw according to claims 1 to 4 and 6, characterized in that the handle is fixed to the frame set back from the blade so that the axes of the handle and the blade are parallel. 12. Scroll saw according to claims 1 to 4, 6 and 11, characterized in that it is provided with a support located at the root of the handle, which extends along the frame in the direction of removal. of the blade so that the saw can rest by this support on the hand which grips the handle during the work of the saw.