GB2030906A

GB2030906A - Honing tool having at least two sets of honing strips

Info

Publication number: GB2030906A
Application number: GB7930897A
Authority: GB
Original assignee: Nagel Maschinen und Werkzeugfabrik GmbH
Current assignee: Nagel Maschinen und Werkzeugfabrik GmbH
Priority date: 1978-09-07
Filing date: 1979-09-06
Publication date: 1980-04-16
Also published as: FR2435325B1; FR2435325A1; DE2838948C2; GB2030906B; DE2838948A1

Abstract

The present specification discloses a honing tool (11) having at least two sets of honing strips (16, 17) whose carriers (34, 35) are separately extensible by the axial movement of at least one axially movable expansion body (20, 21). The expansion body (20, 21) has sloping surfaces (42) between which recesses (23) are located opposite the respective non- extended honing strip carriers. The expansion body (20, 21) is rotatable into positions in which one or the other set of honing strip carriers (34, 35) is located opposite the sloping surfaces (42). To rotate the expansion body through at least a circumferential distance equal to the distance between adjacent honing strip carriers (34, 35), a stepping device (24) is connected to the at least one expansion body (20, 21), the stepping device (24) effecting rotations of the expansion body (20, 21) during the axial return movement of the expansion body in the opposite direction to the direction of extension.

Description

SPECIFICATION Honing tool having at least two sets of honing strips The present invention relates to a honing tool having at least two sets of honing strips.

In particular the present invention relates to a honing tool of the type having at least two sets of honing strips whose carriers are separately extensible by the axial movement of at least one axially movable expansion body having sloping surfaces, the expansion body having, between the sloping surfaces, recesses which are located opposite to the respective non-extended honing strip carriers, and the expansion body being rotatable into positions in which one or other set of honing strip carriers is located opposite the sloping surfaces.

The purpose of honing tools of this kind is to successively extend different types of honing strips, such as coarse honing strips and fine honing strips, so as to be able to perform coarse machining and subsequent fine machining by means of a single tool. Various devices are known for selective actuation of the two sets of honing strips, some of which devices (e.g. British Patent Specification No. 12 07 399) operate with a double cone which, during axial displacement from a central position in one or the other direction, in each case extends one of the two sets.

In accordance with German Offenlegungsschrift 15 77 408, change-over is either effected manually or is controlled by reversing the direction of rotation of the honing tool. Expansion cones are then used whose sloping surfaces are formed on individual vanes. The sloping surfaces are brought into engagement with the honing strip carriers of one or the other set by swinging back and forth as a result of the reversal of the direction of rotation.

The two known devices have the disadvantage that the honing machine has to be set for the special type of honing work. In one case, an expansion rod axially movable in two different directions has to be provided, whilst, in the other case, the direction of rotation of the honing tool has to be reversible. Furthermore, the honing tool of German Offenlegungsschrift No. 1 5 77 408, is extremely expensive to manufacture and, owing to its complexity, is susceptible to trouble during operation.

An aim of the present invention is to provide a honing tool of the kind mentioned initially which can be of simple and operationally reliable construction and which can cooperate with an expansion device of a honing machine which is displaceable back and forth only in an axial direction.

According to the present invention there is provided a honing tool comprising at least two sets of honing strips whose carriers are separately extensible by the axial movement of at least one axially movable expansion body having sloping surfaces, the expansion body having, between the sloping surfaces, recesses which are located opposite the respective non-extended honing strip carriers, and the expansion body being rotatable into positions in which one or the other set of honing strip carriers is located opposite the sloping surfaces, a stepping device being connected to the at least one expansion body and being constructed to convert an axial movement of the expansion body into a rotary movement through at least the circumferential distance between two honing strip carriers of different sets.

During the normal retraction and re-advance of the expansion rod and of the expansion body connected thereto, the stepping device causes the sloping surface, actuating the honing strip carriers, of the expansion body to move towards the During the normal retraction and re-advance of the expansion rod and of the expansion body connected thereto, the stepping device causes the sloping surface, actuating the honing strip carriers of the expansion body to move towards the honing strip carriers of the following set. A greater advantage is that, in the device in accordance with the invention, an optional number of sets of honing strips can be used, for example three or more sets. This is not possible in the devices in accordance with the prior art, since these devices have only two possibilities of change-over.In the present invention, only a different correlation of the angles of rotation of the expansion body to the angular offset between the individual sets is required in order to work with several sets, such as coarse rough-honing strips, an average fineness, and subsequently with a set of finishing honing strips.

The stepping device can be combined with an expansion body in a particularly compact manner.

However, spatial separation between the expansion body and the stepping device would also be possible if this were required by, for example, the spatial conditions in the honing tool.

Preferably the grooves are provided in the expansion body and the pins are provided in the tool body. However, it would also be possible to provide the grooves in the tool body and the pins on the expansion body, or to use a different type of stepping device such as a stepping device having pauls, although the preferred embodiment has the advantage that is operates virtually without movable parts and is thus particularly robust and reliable.

Normally, it will be preferable to incorporate the stepping device in the honing tool or to provide it thereon. However, in specific embodiments, it is also possible to provide the stepping device in the honing-machine. In this latter case, the expansion body of the honing tool is not only rigidly coupled to the expansion rod in an axial direction, but is also coupled thereto so as to be non-rotatable relative thereto, so that the rotary movement can be transmitted to the expansion body.

The present invention will now be further described by way of example, with reference to the accompanying drawings, in which:~ Fig. 1 is a longitudinal section through one embodiment of a honing tool, constructed according to the present invention, taken on the line I-I of Fig.4, Fig. 2 is a view of the expansion body showing the combined stepping device, Fig. 3 is a section through a detail, taken on the line Ill-Ill of Fig.2, Fig. 4 is a section or a view taken on the line lV-lV, Fig. 5 is a section taken on the line V-V of Fig.

2, and Fig. 6 is a cross section through the honing tool, taken on the line VI-VI of Fig. 1.

The honing tool 11 illustrated in the drawings can be mounted, by means of an optional chuck 12, on the rotatingly and upwardly and downwardly driven working spindle 13 of a honing machine 14 of conventional construction. The honing machine has an expansion rod 15 which is movable in an axial direction, namely downwardly from a normal position, in order to expand the honing strips 1 6, 17 of the tool 11.

The honing tool has substantially tubular tool bbdy 1 8 in the interior of which is arranged an axially movable actuating rod 1 9 for two expansion bodies 20, 21. The actuating rod 19 is coupled to the expansion rod 15.

The lower expansion body 21, that is to say, the expansion body nearer to the free end 22 of the tool, is in the form of a cone which tapers towards this free end and which incorporates four notches or slots which, including their bottoms, extend substantially axially and are staggered through 900 relative to one another. Since the bottom region of the expansion body 20 is of the same construction, this shape can be seen in Fig. 4.

In the case of the expansion body 20, a stepping device 24 is, of course, connected to the actual expansion body and is formed in the periphery of a substantially cylindrical extension of the expansion body 20 which extension is provided on the end of the body 20 nearest to the machine 14. The cylindrical extension has internal bore 25 in which a projecting portion 26 of the actuating rod 19 is mounted by means of a projecting shoulder and a spring ring, so as to be rotatable but not axially displaceable.

The stepping device 24 includes guides, also shown particularly in Fig. 2, which are in the form of grooves and which are provided in the otherwise substantially cylindrical surface of said extension. Each set of guides has a substantially axially extending guide 27 in the form of a groove which is connected to the adjacent axial guide 27 by means of a guide surface which slopes relative to the central axis 29 of the tool and of the expansion body. The bottom of the guide groove 27 rises in a central region 30 from the free end 22 towards the end nearest the machine 14 and terminates in a shoulder 31, the face of which shoulder 31 slopes relative to the longitudinal axis of body 20 but which otherwise extends radially.

Similarly, the bottom of the guider groove 28 slopes in the direction of the arrow 32 and terminates at a shoulder 33 in the adjacent guide groove 27.

Eight sets of guides 27 and 28 are provided around the periphery of the illustrated tool, and each guide 28 slopes in the same direction.

Viewed in the direction of the arrow 32, the sloping guide commences in a central region of the axially extending guide 27 and terminates at that portion of the adjacent guide 27 which is nearer the free end 22. Thus, the number of guides provided is twice that of the number of slots 23.

The honing strips 16, 17, of which the strips 16 are coarse or rough-honing strips and, as may be seen in Fig.6, are also of different configuration, and wider, than the fine-honing strips 17, are mounted on honing strip carriers 34, 35 in the form of plates or bars which are guided in radial slots in the tool carrier. Four rough-honing strips 16, offset through 900 relative to one another, and four fine-honing strips 17, offset through 900 relative to one another, are provided. The two sets each comprising four strips are offset through 450 relative to one another. It is obvious that, instead of honing strips in the proper sense, that is to say, a grinding body secured to a strip by means of bonding agents, other types of grinding bodies can be used, such as diamond coatings provided on a metal carrier, or the like.

Guide bars 36 are arranged between each two honing strips.

Each of the honing strip carriers 34,35 has two sloping surfaces 37, and one of each two sloping surfaces faces an expansion body 20, 21. The honing strips are pulled resiliently inwardly by means of conventional spring rings 38 and, when they are not expanded, they can abut against a stop 39 on the tool body, so that their inward movement is limited.

In the illustrated embodiment, four pins 41 each loaded by a spring 40 are provided circumferentially in the tool body and adjacent to the stepping device 24 and extend into the guides 27, 28 and, by virtue of the fact that they are spring-loaded, can be pressed back by the chamfered bottom such as the region 30 of the guide 27.

The honing tool illustrated in Figs 1 to 6 operates in the following manner: The starting position is that position in which the expansion bodies are in their upper, retracted positions and are located in a rotary position such that their conical outer surfaces 42 are located opposite the sloping surfaces 37 of the honing strip carriers 34 for the rough-honing strips 1 6.

Alternatively, the conical outer surfaces of the expansion bodies could be planar sloping surfaces, so that the expansion cone would be in the form of a polyhedral pyramid. When the honing tool is put into operation in a conventional manner so that it rotates and moves up and down, the expansion bodies 20,21 are also displaced downwardly during a downward movement of the expansion rod 5 effected to expand the honing tool, and the expansion bodies move the rough-honing strips 16 outwardly into their working positions.

During the downward movement of the expansion rod 15 from its upper normal position into the working position and beyond to the desired measured value, the expansion body 20 is displaced downwardly to such an extent that the pin 41, initially located below the sloping region 30 of the guide 27, moves beyond the slope 30 into the upper region 43 of the guide 27. Thus, each pin 41 moves in the direction of the arrow 44 of Fig. 2 and is pushed back on the slope 30 against the force of the spring 41 and again springs radially inwardly behind the shoulder 31.

When the desired amount of material has been removed during the rough-honing operation, the expansion rod 15 is again moved upwardly into its normal position. The expansion body 20 follows these movements. The pin then moves initially in the guide 27, but is then guided by the sloping shoulder 31 along the sloping portion of the guide 28 (see Figure 3) until it drops into the adjacent axially extending guide 27 behind the shoulder 33. During the movement of the pin in the guide 28, the stepping device 24 and the expansion bodies 20, 21 have been further rotated by one step, that is to say, 450 in the present case. As a result of the coupling formed by the flange 26, the expansion bodies 20, 21 can rotate freely relative to the actuating rod 19 and are fixed in their rotary position only by the pins 41.

As a result of the eighth of a full rotation during retraction of the expansion rod, the expansion bodies 20,21 have now been rotated such that the carriers 34 of the rough-honing strips 16 are located opposite the slots 23, whilst the carriers 35 of the fine-honing strips 17 are located opposite the conical outer surfaces 42. Free rotation of the expansion bodies between the honing strip carriers is rendered possible by virtue of the fact that the honing strip carriers abut against the stops 39 and thus do not engage the slots 23 when the expansion rod is retracted.

When the expansion rod 15 is again moved downwardly after the fine-honing strips are in their working positions, fine-honing strips 1 7 are extended by abutment of the sloping surfaces 37 against the conical outer surfaces 42, while the rough-honing strips 16 remain in their retracted positions. This state is shown in Fig. 1. In the same manner as that described previously, the pin 41 thereby moves in the guide 27 beyond the slope 31 into the region 43 which is normally reached before the honing strips come into working contact.

Thus, it will be seen that automatic change over between rough-honing and fine-honing is effected by the normal movement of an expansion rod of a conventional honing machine, and, in the same manner as described, switching back to rough-honing for the next working operation is also effected automatically.

A large number of modifications of the described and illustrated embodiment are possible. Thus, for example, the grooves 27, 28 could be provided in the tool body, and the pins could be mounted on a member connected to the expansion body. Alternatively, the stepping device 24 could be arranged within the machine spindle 12. In this case, the two expansion bodies could be in the form of the expansion body 21 and would be connected axially and rigidly by way of an actuating rod to the stepping device forming part of the honing machine. Alternatively, the stepping device could be mounted as an accessory on a conventional honing machine in the manner of an adaptor. Although the stepping device in accordance with the invention does not substantially increase the cost of manufacturing the honing tool, the actual tool could be still further simplified in this manner, this possibly being advantageous when a large number of individual honing tools are to used in a machine.

Claims

1. A honing tool comprising at least two sets of honing strips whose carriers are separately extensible by axial movement of at least one axially movable expansion body having sloping surfaces, the expansion body having, between the sloping surfaces, recesses which are located opposite the respective non-extended honing strip carriers, and the expansion body being rotatable into positions in which one or the other set of honing strip carriers is located opposite the sloping surfaces, a stepping device being connected to the at least one expansion body and being constructed to convert an axial movement of the expansion body into a rotary movement through at least the circumferential distance between two honing strip carriers of different sets.

2. A honing tool as claimed in claim 1, in which the stepping device effects rotation of the expansion body during the axial return movement of the expansion in the opposite direction to the direction of extension.

3. A honing tool as claimed in claim 1 or 2, in which the stepping device is provided directly on an expansion body.

4. A honing tool as claimed in any one of the preceding claims, in which the stepping device has a plurality of axially extending guides and sloping guides which interconnect the latter and which cooperate with at least one complementary guide projection.

5. A honing tool as claimed in claim 4, in which the all the sloping guides slope in one direction.

6. A honing tool as claimed in claim 4 or 5, in which the axially extending guide and optionally the sloping guide, have on their bottoms a shoulder which guides the guide projection into a zig-zag path relative to the expansion body.

7. A honing tool as claimed in any one of the claims 4 to 6, in which the guides are grooves and the guide projections are pins.

8. A honing tool as claimed in claim 7, in which the pins are spring-loaded.

9. A honing tool as claimed in any one of claims 6 to 8 in which the bottoms of the axially extending and/or sloping grooves have a radially sloping region which merges into a lower region by way of a shoulder.

10. A honing tool as claimed in any one of the claims 3 to 9, in which the grooves are provided in the expansion body, and the pins are provided in the tool body.

11. A honing tool as claimed in any one of the preceding claims, in which the honing strip carriers have a limiting stop which limits the inward movement of the honing strip carriers.

12. A honing tool as claimed in any one of the preceding claims, in which a coupling which is freely rotatable, but which transmits axial movements, is connected to the expansion body.

13. A honing tool as claimed in any one of the preceding claims, in which the expansion body is connectible to the stepping device, arranged on or in a honing machine, so as to be non-rotatable relative thereto and also to transmit axial movements.

14. A honing tool constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.