GB2198492A

GB2198492A - Drive transmission for a machine tool including a planetary gearing

Info

Publication number: GB2198492A
Application number: GB08622669A
Authority: GB
Inventors: Peter Banks Mcmaster
Original assignee: H & M Machinery Ltd
Current assignee: H & M Machinery Ltd
Priority date: 1986-09-19
Filing date: 1986-09-19
Publication date: 1988-06-15
Also published as: GB8622669D0

Abstract

Input shaft (11) drives a sun gear (13) and an output sleeve (16) is integral with the planet carrier (15). A splined connection (18a) selectively holds the ring (17) stationary and an electromagnetic clutch 22 selectively connects the ring (17) to the output sleeve (16) for direct drive. The splined connection (18a) is engageable by a piston and cylinder (19a, 21). The position of the piston (21) is preferably sensed by a proximity switch (23) which inputs to electronic control means for the gearing and a variable speed D.C. electric motor. <IMAGE>

Description

"DRIVE TRANSMISSION" The present invention relates to a drive transmission and more particularly to one providing for a speed change.

At the present time, multi-speed machine tools are generally driven by an A/C motor acting through a manual gear box. The latter is noisy, provides a torturous drive path and does not lend itself to electronic control.

It is an object of the present invention to provide a more efficacious form of drive transmission for the use inter alia in multispeed machine tools.

There is provided by the present invention a drive transmission for use inter alia in multi-speed machine tools, comprising a fixed-ratio reduction gear, a sun and planet gear driven from the reduction gear, a clutch which, on engagement, connects the gear ring of the sun and planet gear to the clutch output member to drive an output member, and a piston and cylinder device operating a member to engage with the ring gear to prevent rotation thereof and cause rotation of the planet carrier by the sun pinion of the sun and planetary gear; the planet carrier being connected to the output member to drive the member on such rotation of the planet carrier; whereby, when said clutch is in operation but not said piston and cylinder device, the output member is driven at one speed by the gear ring of the sun and planetary gear and, when said piston and cylinder device is in operation but not said clutch, the output member is driven at another and lesser speed by the planetary carrier of the sun and planetary gear.

The drive transmission is preferably used with an electronic control device to provide actuate/inhibit signals such as to prevent simultaneous operation of the clutch and the piston and cylinder device.

It is also preferred that a D/C motor be used as the motive power source to drive the input reduction gear; the motor being of the kind comprising an electronic infinitely-variable speed control.

Advantages of the present invention are that it provides a "straight through" constant mesh gearing with minimum gears, and therefore reduces noise, it is compact, provides high poler throughout the speed range and is easily adapted to respond to electronic signals e.g. from a computor, and to provide signals monitoring its speed for feedback to an electronic control device.

The present invention asill now be described with reference to the accompanying drawing the sole figure of which (Fig.1) is a central longitudincl section of a pcrt of an embodiment of a transmission according to the present invention.

Referring now to the sole figure, that part of the drive transmission which is illustrated is intended to be driven by a D/C motor (not shown) provided with an electronic infinitely variable speed control, having an effective range of some 700 to 50CO rpm and transmitting in this speed range a constant power. The motor drives G conventional fixed-ratio arrangement (not shown) providing a reduction of the motor speed of e.g. 22 to 1.

The drive from the fixed-ratio arrangement is applied to a shaft 11 which, for ease of construction, is in two pElts 11a lib secured together by a pin 12.

The sun wheel 13 of a sun and planet gear is secured on shaft part lia and meshes with three planet heels 14 (only one planet wheel 14 is shown in the drawing), the planet wheels are ro tatable on shifts 14 > secured to a planet carrier 15 and the planet carrier 15 is fast with a drive output sleeve 16 rotatable on shaft part 11G. The gear ring 17 of the sun and planet gear is defined by an annular member 18.

An annular housing 19, held against rotation, houses a bearing 20 for shaft part 11b and further defines an annular, hydraulic cylinder 19a concentric with the axis of shaft 11. An annular piston member 21 axially slidable in cylinder 19a presents an annular splined extension 21 > which, in an extended position of member 21 relative to housing 19, engages a complementary splined bore 18= in member 18. The piston member 21 is retained against rotation relative to member 19 by pins 19b presented by member 19.

The member 18 further slidably supports one half 22a of an electro magnetic clutch, generally indicated by-numeral 22, the other half of which is secured on output sleeve 16. The halves 22a and 22b are engaged when radial teeth 22c and 22d respectively engage.

As illustrated a bearing 23 supports member 18 on shaft 11, a bearing 24 supports sleeve 16 on shaft 11 and a be ring 25 supports member 18 on sleeve 16.

The drive transmission arrangement operates as follows.

with the drive applied to shaft 11 causing shaft parts 11a and 11b to rotate and with the electromagnetic clutch 22 open and inoperative, the piston member 21 is in its extended position wherein splined extension 21a is meshed with splined bore 18a whereupon member 18 is held against rotation and the sun and planet gear ring 17, is stationary. The drive to shaft 11 rotates sun wheel 13, drive is transmitted to planet wheels 14 and, because planet gear ring 17 is stationary, the planet wheels 14 rotate on their respective shafts to transmit drive to the planet carrier which rotates to transmit drive to the drive output sleeve 16.

Vith the drive applied to shaft 11, the electromagnetic clutch 22 closed and operative and the piston member 21 retracted within cylinder 19a to disengage the splined extension 21a from bore 18a, the annular member 18 is released for rotation and fast with the sleeve 16. The rotation of sun wheel 13 is transmitted to planet wheels 14 but as member 18 is rotatable the planet wheels 14 rotate member 18 and drive is transmitted to the sleeve 16 via the electromagnetic clutch 22. As stated hereinbefore the planet carrier 15 is frost with output sleeve 16 so that a positive drive is again obtained.

The route for the drive transmission is controlled by a proximity switch 23 mounted in housing 19 and which notes the proximity of the piston member 21 in its retracted position, indicative of disengagement of the splined extension 21a from splined bore 18a, and via a circuit (not shown) allows the electrsmagnetic clutch 22 to operate. hen the proximity of piston member 21 is not detected by switch 23 the switch 23 so affects the control circuit that electromagnetic clutch 22 is disengaged.

Thus, with the transmission arrangement as proposed above the clutch and piston and cylinder devices cannot be operated simultaneously. hen the clutch is in operation, the sun and planetary gear drives the output sleeve 16 with a 1:1 ratio via the gear ring 17.

Qhen the piston and cylinder device is in operation, the output sleeve 16 is driven ith a speed reduction ratio, in this instance, of 5:1 via the planet gears 14, and the planet carrier 15.

Due to the speed variation possible by controlling the motor, the different ratios provided by sun and planetary gear perrit a continuous variation over a speed range such as to make the transmission suitable for a wide range of machines and applications with the maximum speed achievable in the lower speed range of the transmission (i.e. with the piston and cylinder device in operation) being substantially equal to the minimum speed in the higher speed range (i.e. with the clutch in operation).

s transmission according to the present invention can readily be used to provide the drive for an existing machine and thus adapt it fo > - computor control.

It Bill be cpyreciated that for ease of construction and/or assembly of the drive transmission arrangement certain elements and members illustrated as mono-block elements may comprise sub-assemblies and, in partlculaz, the an > < ular member 18 and the housing 19 c n be of composite construction.

Claims

FHT WE CLAIM IS:

1. A drive transmission for use in multi-speed machine tools comprising a fixed-ratio reduction gear, a sun and planetary gear driven from the reduction-gear, a clutch which on engagement connects the gear ring of the sun and planetary gear to the clutch output member to drive an output member, and a piston and cylinder device operating a member to engage with the ring gear to prevent rotation thereof and cause rotation of the planet carrier by the sun pinion of the sun and planetary gear; the planet carrier being connected to the output member to drive the member on such rotation of the planet carrier; whereby, when said clutch is in operation but not said piston and cylinder device, the output member is driven at one speed by the gear ring of the sun and planetary gear and, when said piston and cylinder device is in operation but not said clutch, the output member is driven at another and lesser speed by the planet carrier of the sun and planetary gear.

2. A drive transmission as claimed in claim 1 in combination with a DC motor arranged to drive the drive transmission.

3. A drive transmission and DC motor combination as claimed in claim 2 in which said DC motor is of the kind including an electronic infinitely-variable speed control.

4. A drive transmission as claimed in claim 1, 2 or 3 in which said clutch comprises an electro-magnetic clutch.

5. A. drive transmission as claimed in claim 1, 2, 3 or 4, including means for preventing simultaneous operation of the clutch and said piston and cylinder device.

6. A drive transmission as claimed in claim 5 in which said means comprise an electronic control device which provides~ actuate/inhibit signals such as to prevent simultaneous operation of the clutch and the piston and cylinder device.

7. A drive transmission as claimed in claim 6 in which said electronic control device comprises a proximity switch in proximity to the piston of said piston and cylinder device and said proximity switch transmits actuate/inhibit signals to said clutch in dependance upon te position of the said piston relative to its co-operating cylinder.

8. A drive transmission as claimed in any preceding claim in which the fixed ratio reduction gear applies drive to a shaft which drives the sun wheel of the sun and planetary gear and the said shaft and s#id output member rotate about a common axis

9. h drive transmission as claimed in claim 8 in which said sun and planetary gear and the said clutch are concentric with the said common axis.

10. A drive transmission substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Amendments to the claims have been filed as follows 1. A drive transmission for use in multi-speed machine tools comprising a fixed-ratio reduction gear, a sun and planetary gear driven from the reduction gear, a non-slip clutch which on engagement connects the gear ring of the sun and planetary gear to the clutch output member to drive an output member, and a piston and cylinder device operating a member to engage in a non-slipping manner with the ring gear to prevent rotation thereof and cause rotation of the planet carrier by the sun pinion of the sun and planetary gear; the planet carrier being connected to the output member to drive the member on such rotation of the planet carrier; whereby, when said clutch is in operation but not said piston and cylinder device, the output member is driven at one speed by the gear ring of the sun and planetary gear and, when said piston and cylinder device is in operation but not said clutch, the output member is driven at another and lesser speed by the planet carrier of the sun and planetary gear.

3. A drive transmission and DC motor combination as claimed in claim 2 in which said DC motor is of the kind including an electronic infinitel-y-varisble speed control.

4. A drive transmission as claimed in claim 1, 2 or 3 in which said clutch comprises an electromagnetic clutch.

5. A drive transmission as claimed in claim 1, 2, 3 or 4 including means for preventing simultaneous operation of the clutch and said piston and cylinder device.

6. A drive transmission as claimed in claim 5 in which said means comprise an electronic control device which provides actuate/inhibit signals such as to prevent simultaneous operation of the clutch and the piston and cylinder device.

7 A drive transmission as claimed in claim 6 in which said electronic control device comprises a proximity switch in proximity to the piston of said piston and cylinder device and said proximity switch transmits actuate/inhibit signals to said clutch in dependence upon the position of the said piston relative to its co-operating cylinder.

8. A drive transmission as claimed in any preceding claim in which the fixed ratio reduction gear applies drive to a shaft which drives the sun wheel of the sun and planetary gear and the said shaft and said output member rotate about a common axis.

9. A drive transmission as claimed in claim 8 in which said sun and planetary gear and the said clutch are concentric with the said comnon axis.