BROACH FOR BROACHING MACHINE

Abstract

A broach for a broaching machine is provided, which has a toothed sheet with hard-metal teeth, formed by one or more segments arranged in longitudinal correlation and a sheet-holding support in which the toothed sheet is placed; characterized in that the sheet-holding support has a recess into which a base of the toothed sheet with matching configuration fits, in order to establish mechanical coupling between the two, and in that the sheet-holding support includes tightening means for securing the toothed sheet in position in the sheet-holder.

Claims

1. A broach for a broaching machine, which comprises a toothed sheet with hard-metal teeth, formed by one or more segments arranged in longitudinal correlation and a sheet-holding support in which the toothed sheet is placed; wherein the sheet-holding support has a recess into which a base of the toothed sheet with matching configuration fits, in order to establish mechanical coupling between the two, and in that the sheet-holding support includes tightening means for securing the toothed sheet in position in the sheet-holder.

2. The broach for a broaching machine according to claim 1, wherein the tightening means are screws screwed into recesses of the sheet-holder and acting in the perpendicular direction with respect to the theoretical longitudinal axis of the toothed sheet.

3. The broach for a broaching machine according to claim 1, wherein a dolly uniformly distributing the tightening forces of the screws is arranged between the base of the toothed sheet and the tightening means.

4. The broach for a broaching machine according to claim 1, wherein the recess in which the base of the toothed sheet fits has a dovetail shape.

Description

DESCRIPTION OF THE FIGURES

[0018] FIG. 1 shows section A-A indicated in FIG. 2.

[0019] FIG. 2 is a profile view of the sheet-holding support 1 of a conventional broach.

[0020] FIG. 3 shows an elevation view of a conventional toothed sheet 2.

[0021] FIG. 4 corresponds to the elevation view of the sheet-holding support 1 and the toothed sheet 2 already assembled therein.

[0022] FIG. 5 is a profile view of FIG. 4.

[0023] FIG. 6 is a perspective view of a sheet-holding support 3 made according to this invention.

[0024] FIG. 7 corresponds to a profile view of FIG. 6.

[0025] FIG. 8 shows the elevational view of the sheet-holding support 3.

[0026] FIG. 9 is cross-section I-I indicated in FIG. 8.

[0027] FIG. 10 is cross-section II-II indicated in FIG. 8.

[0028] FIG. 11 is an elevation view of a toothed sheet 4 made according to the invention.

[0029] FIG. 12 is the profile view of the preceding figure.

[0030] FIG. 13 shows a cross-section of the broach given at the height of one of the screws 6.

[0031] FIG. 14 is also a cross-section of the broach but given here at the height of the stop 8.

DETAILED DESCRIPTION OF THE INVENTION

[0032] The object of the present invention is a broach as a tool of a broaching machine, and more specifically a broach in which the rows of teeth are made of hard-metal, for rough machining works.

[0033] FIGS. 1 to 5 show a conventional, already known embodiment of broaches of this type, identified as glue-secured broaches.

[0034] In this case, the conventional broach is made up of a support body or sheet-holder (1) and a toothed sheet (2) having the corresponding hard-metal teeth of the broach. The toothed sheet (2) may be formed by one or more segments (2.1) arranged one after the other, in longitudinal correlation, where it is seen in FIG. 4 that it is formed by three segments (2.1).

[0035] According to this known solution, the sheet-holder (1) defines a recess (1.1) for fitting therein the segments (2.1) forming the toothed sheet (2), and securing is carried out by means of gluing, which prevents coating the hard-metal teeth of the sheet by means of PVD or CVD coating techniques, thereby reducing the service life of the broach.

[0036] According to the invention, the broach continues to be formed by a sheet-holder (3), see FIG. 6, and by the toothed sheet (4) depicted in FIGS. 11 and 12, and is formed by one or more segments arranged in longitudinal correlation defining the hard-metal teeth.

[0037] According to the invention, the sheet-holder (3) here defines a preferably dovetail recess (3.1) in matching correspondence with the configuration of the base (4.1) of the toothed sheet (4), such that the segment or segments defining the toothed sheet (4) are assembled in the sheet-holder (3) by a mechanical coupling, preferably a mechanical dovetail coupling.

[0038] Preferably the dovetail coupling has been selected as it provides optimal conditions, but other alternative and known coupling shapes, such as a T-shaped, double, or half dovetail assembly, etc., could be contemplated without altering the essence of the invention.

[0039] Below the dovetail recess (3.1) there is another recess (3.2), see FIG. 7. This other recess (3.2) is intended for housing a strip (5) acting as a dolly, see FIG. 13.

[0040] The sheet-holder (3) also defines threaded holes (3.3) for securing screws (6), see FIG. 13. According to this embodiment and once the segments forming the toothed sheet (4) are assembled in the sheet-holder (3) by means of the mechanical dovetail coupling, they are secured in position by means of the tightening exerted by the screws (6). These screws (6) impinge against the lower portion of the dolly (5) in a direction perpendicular to same, such that this dolly (5) uniformly distributes the tightening pressures of the screws (6), on the segments of the toothed sheet (4).

[0041] Once the screws (6) are tightened with a preset tightening torque, they are secured in position by means of anchor pins (7) which, as seen in FIG. 13, act in the perpendicular direction with respect to the screws (6) by means of being screwed into recesses (3.4) of the sheet-holder (3).

[0042] These tightening screws (6) can obviously vary in number and arrangement, without altering the essence of the invention, and can even be replaced with other known tightening means which allow the toothed sheet (4) to be secured in position in the sheet-holder (3).

[0043] As seen in the cross-sectional view of FIG. 10, at one of the ends of the sheet-holder (3), namely at the end where strains of the broach are produced during the working phase, there is a cavity (3.5) in which a stop (8) is included, see FIG. 14, and carries out the functions of a mechanical stop for the toothed sheet (4) in the direction in which stresses of the broach are produced during the working phase.

[0044] The fact that this stop (8) is formed by another conventional solution and is not even an attached element, and it is the actual sheet-holder (3) that forms it, would not alter the essence of the invention in any way. It has further been provided for that it may not even be required in some cases.