WO2000062979A1

WO2000062979A1 - Gripper jaws for tools of different diameter

Info

Publication number: WO2000062979A1
Application number: PCT/US2000/009859
Authority: WO
Inventors: Aaron Durbin
Original assignee: Electro Scientific Industries, Inc.
Priority date: 1999-04-15
Filing date: 2000-04-13
Publication date: 2000-10-26
Also published as: AU4456600A

Abstract

A pair of gripper jaws are provided to gripping tools of different diameter. Each gripper jaw includes a first gripping surface for gripping small diameter tools and a second gripping surface for gripping larger diameter tools. The gripping surfaces are formed by a cylindrical groove superimposed over a V-shaped groove. The V-shaped groove is configured to provide preferably four points of contact with a first tool when gripped by both jaws. The cylindrical groove is configured to grip about twenty five per cent of the circumference of a second tool when gripped by both jaws. The gripping surface of the gripper jaws is constructed and arranged to securely grip and hold tools of different diameter without requiring a change of gripping jaws.

Description

GRIPPER JAWS FOR TOOLS OF DIFFERENT DIAMETER

Technical Field

This invention is directed to gripper jaws for use with a tool changer for changing tools having various diameters, such as, for example, ringed drill bits and ringless drill bits.

Background of the Invention

In machining processes it is desirable to provide a tool changer that is versatile to accommodate tools of various diameters. For example, in the processing of printed circuit boards some applications use a ringless drill bit that is gripped by its shank by gripping jaws of a tool changer during a tool change. Other applications may use a ringed drill bit that includes a larger diameter ring on the shank that is gripped by the gripper jaws of the tool changer.

The gripper jaws currently in use are only capable of gripping either a ringless drill bit or a ringed drill bit but not both. There are a variety of movable gripper jaws for gripping tools. For example, one type of movable jaws open and close by pivoting in an angular motion. Other jaws open and close by sliding toward and away from each other to grip the tool. Some of the sliding type of gripper jaws have a stationary jaw with an opposite jaw that slides toward and away from the stationary jaw to grip the tool. However, these gripper jaws only have one gripping surface each for contacting the tool. The gripping surfaces may be effective for gripping smaller diameter tools due to the fact that the gripping surfaces of the jaws provide adequate points of contact with the smaller diameter tool. However, while the gripping surface may be adequate for smaller diameter tools it may not be very effective for larger diameter tools. This is because the gripping surfaces of the gripper jaws do not provide enough contact with the larger diameter tools to adequately grip it. In fact, using the same gripping surfaces for both small and larger diameter tools has resulted in tool change failures on larger diameter ringed tools. Therefore, a different set of gripping jaws must be used for larger and smaller diameter tools.

Summary of the Invention In accordance with the preferred embodiment of the present invention the gripper jaws of the present invention overcome the above disadvantages by utilizing gripping surfaces that are constructed and arranged to effectively grip tools of different diameters.

The gripper jaws of the present invention are adapted for use with a tool changer that includes movable gripper jaws that are identical with each gripper jaw including a base for mounting to an associated jaw mount by bolts or other fasteners. The base has a ridge that extends from the bottom surface of the base that is received in a slot in the jaw mount to help secure and align the gripper jaw. The jaw mounts are operable to reciprocate within the jaw body to open and close in a known manner.

Each gripper jaw includes a portion that extends substantially perpendicular to the base and has an inner face that forms gripping surfaces. In order to securely grip tools of different diameter the gripper j aws of the present invention have a tool gripping face that provides separate gripping surfaces, one gripping surface for smaller diameter tools such as ringless drill bits and another gripping surface for larger diameter tools such as ringed drill bits. One of the gripping surfaces is formed by a V-shaped groove and the other gripping surface is formed by a cylindrical groove superimposed over the V-shaped groove. The V-shaped groove is configured to provide at least three points of contact with smaller diameter tools. The cylindrical groove is configured to grip a portion of the circumference of larger diameter tools to provide a secure hold on the tool. This gripping profile of the gripper jaws is constructed and arranged to securely grip and hold tools of different diameter without requiring a change of gripping jaws. It is an object of the present invention to provide gripper jaws that securely grip and hold tools of different diameters. It is another object of the present invention to provide gripper jaws that have a compound gripping surface.

Additional objects and advantages of this invention will be apparent from the following detailed description of preferred embodiments thereof which proceeds with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 is a front elevation view of an automated drilling machine utilizing the gripper jaws of the present invention.

Figure 2 is a perspective view of a tool changer with the gripper jaws of the present invention holding a ringless drill bit.

Figure 3 is a perspective view of the tool changer with the gripper jaws holding a ringed drill bit.

Figure 4 is a perspective view of a gripper jaw of the present invention. Figure 5 is an enlarged partial top view of the gripper jaw of the present invention showing the gripping surfaces in relation to ringed and ringless tools.

Figure 6 is a view similar to Fig. 5 showing the angle of the V-shaped groove and the radius of the cylindrical groove.

Figure 7 is a simplified block diagram illustrating a controller and its general connection with elements of the tool changer system. Detailed Description of Preferred Embodiment

The tool changer of the present invention is preferably used in automated drilling systems 2 of the type shown in Fig. 1 that perform operations such as drilling holes in printed circuit boards. The drilling system typically includes at least one spindle 4 that drives a replaceable drilling tool and a workpiece carrier 6 that moves within a plane, the spindle 4 being operable to move the tool relative to the workpiece carrier 6. The drilling system 2 also includes a tool changer system that includes a tool magazine 8 for releasably holding a plurality of tools, the tool magazine 8 being operable to move relative to the workpiece carrier 6. The tool changer system includes a tool gripper 10 movable relative to the workpiece carrier 6 and having gripper jaws that open and close to grip the tool by its shank and transfer it from the tool magazine 8 to the spindle 4. Some applications require tools having different diameters. For example, some applications may use a ringless drill bit having a shank diameter of about .125 inches. Other applications may use a ringed drill bit having a plastic ring on the shank. These ringed drill bits are usually gripped by the ring which typically has a diameter of about .300 inches. The tool gripper 10 of the present invention is adapted to grip both larger and smaller diameter tools. Although described as being used with machines for drilling printed circuit boards, it is understood that the tool gripper of the present invention may also be used in other systems for other operations, such as, for example, milling or routing.

Figures 2 and 3 illustrate the tool changer 10 utilizing the gripper jaws of the present invention to hold tools of different diameter. The tool changer 10 generally includes a jaw body 12 that is moved into and out of position for removing and inserting tools, such as drills to perform various operations on a workpiece, such as a printed circuit board. The jaw body 12 includes a pair of opposed gripper jaws 14 mounted on jaw mounts 16 within the jaw body 12. The jaw mounts 16 are movable within the jaw body 12 along an axis toward and away from each other to open and close the gripper jaws 14. The preferred embodiment of the gripper jaws 14 are of the sliding type with each jaw 14 sliding toward and away from each other to open and close. The gripper jaws 14 are preferably pneumatically operated through pneumatic lines 18 and 19. However, it is understood that the gripper jaws 14 could also be hydraulically or electrically operated. Although slidable jaws are shown and described in the preferred embodiment it is possible that one jaw 14 may be stationary and the opposite jaw movable to open and close the jaws. Furthermore, the jaws may be of the type that pivot to open and close.

The gripper jaws 14 are capable of effectively gripping small diameter tools such as a ringless drill bit 20 (Fig. 2) and larger diameter tools such as a ringed drill bit 22

(Fig. 3). Since the gripper jaws 14 are identical only one of the gripper jaws 14 will be described. Referring now to Fig. 4, each gripper jaw 14 has a base portion 20 for mounting onto an associated jaw mount 16 and a body portion 26 that extends substantially perpendicular to the base portion 20. The base portion 20 includes a ridge 28 that extends downwardly and is received in a slot 30 in the jaw mount 16. The gripper jaw 14 is secured to the jaw mount 16 by bolts 32 and 33 extending through threaded openings 34 and 35 in the base portion 24.

The gripper jaw 14 includes a gripping face 36 formed by the top portion of the gripper jaw 14 for gripping a tool. The gripping face 36 is formed with a V-shaped groove 38 that extends the length of the gripping face 36. As can best be seen in Figs. 5 and 6 the V-shaped groove 38 preferably forms an angle A of 110 degrees and has a depth from the gripping face 36 of about .069 inches. These dimensions are best for gripping a ringless drill bit 20 having a diameter of about .125 inches. As can best be seen in Fig. 5 the dimensions of the V-shaped groove 38 allow it to contact the shank of the ringless drill bit 20 (shown in phantom). Each side of the V-shaped groove 38 provides a point of contact with the ringless drill bit 20 so that when it is gripped by both gripper jaws 14 there are four points of contact between the gripper jaws 14 and the ringless drill bit 20 providing a secure and forceful hold.

To provide a secure grip for larger diameter tools, such as, for example, the ringed drill bit 22, the gripping face 36 has a cylindrical groove 42 superimposed over the V-shaped groove 38. The cylindrical groove 42 preferably has about the same diameter as the ring on the ringed drill bit 22 to provide more surface contact for a more secure and strong grip. In this preferred embodiment the cylindrical groove 42 also extends the length of the gripping face 36 and has a radius R of about .150 inches for gripping ringed drill bits that typically have a diameter of about .300 inches. The cylindrical groove 42 provides a contact surface that covers approximately twenty five per cent of the circumference ring of the ringed drill bit 22 when its gripped by both gripper jaws 14 providing a secure and forceful hold. In the preferred embodiment the cylindrical groove 42 is provided with a shelf 44 upon which the ring of the ringed drill bit 22 rests. Since the ring of the drill bit 22 is typically made of plastic there is a limited amount of friction between the gripper jaws 14 and the ring. The shelf 44 provides a stop to limit and control the depth of insertion of the tool into the spindle 4. The shelf 44 is formed with a diameter of about .17 inches and only extends about the cylindrical groove 42. It is understood that the angular dimension of the V-shaped groove 36 as well as the diameter of the superimposed cylindrical groove 42 may vary according to the size of the tool.

With reference now to Fig. 7 the drilling system 2 includes a controller 50 operably connected to a tool changer actuator drive 52 that drives the tool changer 10 and a tool supply 80, such as the tool magazine 8 in Fig. 1. The controller 50 is also operably connected to a spindle rotary drive 62, a spindle Z drive 60 to move the tool in the Z axis as seen in Fig. 1 , and a positioning system 70 that provides relative movement between the tool changer 10 and the tool supply 80, and also between the tool changer

10 and the spindle 2. As best seen in Fig. 1, each spindle 2 is mounted and controlled by the controller 50 for movement upwardly and downwardly toward the workpiece in a direction along the Z axis. The workpiece carrier 6 is supported for movement in directions along the X axis and along the Y axis (which is not shown but extends into the plane of Fig. 1). The workpiece carrier 6 is controlled by a controller (not shown) that is described in U.S. Pat. No. 4,761,876. The tool changer 10 is mounted adjacent the spindle 2 for transferring tools from the tool magazine 8 to the spindle 2, and vice versa for loading and unloading the spindle 2 with a selected tool.

In order to carry out a tool change, the tool changer 10 is moved under a selected tool held in the tool magazine 8. The tool magazine 8 is then moved down to a tool change position. If necessary, the tool changer 10 is then moved up and the gripper jaws 14 are closed to grip the tool. The tool changer 10 and tool magazine 8 are then moved back to their respective positions. The tool changer 10 is then positioned under the spindle 2 by movement of the workpiece carrier 6. The tool changer 10 is then raised to insert the tool into the spindle 2. Once the tool has been adequately inserted into the spindle 2 the gripper jaws 14 are opened to release the tool and the tool changer 10 is moved back to its initial position so that a drilling operation can be performed.

It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiment of this invention without departing from the underlying principles thereof. The scope of the present invention should, therefore, be determined only by the following claims.

Claims

1. A gripper jaw for gripping tools having different diameters, comprising: a body for mounting to a tool changer having a gripping face that includes a first gripping surface that provides points of contact for a first tool and a second gripping surface that provides surface contact with a second tool.

2. The gripper jaw of claim 1, wherein the second gripping surface is superimposed over the first gripping surface.

3. The gripper jaw of claim 1 , wherein the first gripping surface is a V- shaped groove.

4. The gripper jaw of claim 1 , wherein the second gripping surface is a cylindrical groove.

5. The gripper jaw of claim 3, wherein the second gripping surface is a cylindrical groove.

6. The gripper jaw of claim 3 , wherein the V-shaped groove is formed at an angle of about 110 degrees.

7. The gripper jaw of claim 4, wherein the cylindrical groove is formed at a radius of about .150 inches.

8. The gripper jaw of claim 1 , wherein the second gripping surface includes a support surface for further supporting the second tool.

9. A tool changer for changing tools of different diameters, comprising: a tool changer body having a pair of gripper jaws mounted on the tool changer body for movement along an axis toward and away from each other to open and close for gripping and releasing tools; wherein each gripper jaw includes a gripping face that has a first gripping surface that provides points of contact for a first tool and a second gripping surface that provides surface contact with a second tool.

10. The gripper j aw of claim 9, wherein the second gripping surface is superimposed over the first gripping surface.

11. The gripper jaw of claim 9, wherein the first gripping surface is a V- shaped groove.

12. The gripper jaw of claim 9, wherein the second gripping surface is a cylindrical groove.

13. The gripper jaw of claim 11 , wherein the second gripping surface is a cylindrical groove.

14. The gripper jaw of claim 11 , wherein the V-shaped groove is formed at an angle of about 110 degrees.

15. The gripper jaw of claim 12, wherein the cylindrical groove is formed at a radius of about .150 inches.

16. The gripper jaw of claim 9, wherein the second gripping surface includes a support surface for further supporting the second tool.

17. A gripper jaw for gripping tools having different diameters, comprising: a body for mounting to a tool changer having a gripping face that includes a first gripping surface that provides points of contact for a first tool having a first tool diameter and a second gripping surface that provides surface contact with a second tool having a second tool diameter larger than the first tool diameter, and wherein the first gripping surface does not contact the second tool when the second tool is being gripped by the gripper jaw.

18. The gripper jaw of claim 17, wherein the first gripping surface is a V- shaped groove.

19. The gripper jaw of claim 17, wherein the second gripping surface is a cylindrical groove.

20. The gripper jaw of claim 18, wherein the second gripping surface is a cylindrical groove superimposed over the V-shaped groove.

21. The gripper jaw of claim 17, wherein the second gripping surface includes a stop surface for providing a registration surface to register a depth of insertion of the second tool relative to the gripper jaw.

22. A tool changer for changing tools of different diameters, comprising: a tool changer body having a pair of gripper jaws mounted on the tool changer body for relative movement toward and away from each other to open and close for gripping and releasing tools, wherein each gripper jaw includes a gripping face that has a first gripping surface that provides points of contact for a first tool having a first tool diameter and a second gripping surface that provides surface contact with a second tool having a second tool diameter larger than the first tool diameter, and wherein the first gripping surface does not contact the second tool when the second tool is gripped by the gripper jaw.

23. The gripper jaw of claim 22, wherein the first gripping surface is a V- shaped groove.

24. The gripper jaw of claim 22, wherein the second gripping surface is a cylindrical groove.

25. The gripper jaw of claim 23, wherein the second gripping surface is a cylindrical groove superimposed over the V-shaped groove.

26. The gripper j aw of claim 22, wherein the second gripping surface includes a support surface for registering a depth of insertion of the second tool relative to the gripper jaw.

27. A method for changing tools of different diameter in a machine, comprising: providing a tool changer including a tool changer body having a pair of gripper jaws mounted on the tool changer body for relative movement toward and away from each other to open and close for gripping and releasing tools, wherein each gripper jaw includes a gripping face that has a first gripping surface that provides points of contact for a first tool having a first tool diameter and a second gripping surface that provides surface contact with a second tool having a second tool diameter larger than the first tool diameter, and wherein the first gripping surface does not contact the second tool when the second tool is gripped by the gripper jaw; providing relative motion between the tool changer and a first tool having a first tool diameter to position the first tool relative to the gripper jaw for gripping; performing a first tool change operation, including bringing the first gripping surface of the gripping face into contact with a portion of the first tool having the first diameter to grip the first tool by the tool changer; providing relative motion between the tool changer and a second tool having a second tool diameter larger than the first tool diameter to position the second tool relative to the gripper jaw for gripping; and performing a second tool change operation, including bringing the second gripping surface of the gripping face into contact with a portion of the second tool having the second diameter to grip the second tool by the tool changer.

28. The method of claim 27, wherein the first gripping surface is a V-shaped groove.

29. The method of claim 27, wherein the second gripping surface is a cylindrical groove.

30. The method of claim 28, wherein the second gripping surface is a cylindrical groove superimposed over the V-shaped groove.

31. The method of claim 27, wherein the second gripping surface includes a support surface for registering a depth of insertion of the second tool relative to the gripper jaw.