GB2534593A

GB2534593A - System for mounting a hollow article

Info

Publication number: GB2534593A
Application number: GB1501459.0A
Authority: GB
Inventors: David Sebastien; Ely Mark
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 2015-01-29
Filing date: 2015-01-29
Publication date: 2016-08-03
Also published as: GB201501459D0

Abstract

A system for mounting a bearing on a shaft, e.g. press fit, friction fit, interference fit, comprises a hydraulic nut 100 with an annular cavity 10 and piston 11 displaceable within the cavity 10; a displacement sensor 120 for measuring the displacement of the piston 11 in the cavity 10; a pressure sensor 117 for measuring the pressure in the cavity 10; a pump 115 arranged to pump fluid into the cavity; and a remote display device (200, Fig. 4) which receives one or more of: the sensor signals, the proportion of a range from an initial value to a desired value of pressure or displacement; wherein the sensors 117,120 and remote display device (200, Fig. 4) have wireless communication capabilities, e.g. Bluetooth (RTM). The remote display device (200, Fig. 4) may display the progress of mounting the bearing in the form of a progress bar or by coloured indicia.

Description

SYSTEM FOR MOUNTING A HOLLOW ARTICLE

The invention is related to the subject of mounting hollow articles, for example on a shaft. In particular, the invention can be used for mounting articles having a conical bore on a complementarily-shaped article.

An example of this field is the mounting of a bearing on a frusto-conical seating. In the process of mounting such objects, internal stresses are generated whereby an interference fit is obtained. The conical object is stretched, whereas the shaft is compressed. The objects concerned may comprise various engineering or machinery components, such as gears, bearings, etc. Although high internal stresses lead to a correct interference fit, care should be taken not to overload the objects in order to avoid creep and the development of cracks. On the other hand, low stresses are to be avoided as well having regard to the problems of fretting or stress corrosion.

The Applicant has previously presented a method, in US5779419, for mounting a hollow object having a conically-shaped opening on a conical shaft, which provides a predictable result. That method comprises the steps of: installing the hollow object on the shaft so as to bring the conically shaped surfaces of said object and shaft into abutting relationship; driving the hollow object to a start position for providing an initial interference fit; and driving the hollow object over a predetermined distance from the initial position to a final position for providing a final interference fit. This approach relies upon the correct intervention of a user in actuating a pump with reference to tabulated data so as to obtain the desired initial abutting force and subsequent desired displacement. The Applicant has discovered that the operator's inaccuracy is exacerbated by the inaccuracy of the typical gauges used to measure the pressure and displacement, and also by the inaccuracy of the manual actuation of the hand pump typically used to provide the desired pressure.

According to the invention, there are provided systems defined by claims 1 and 5. By the use of the systems, the article may be mounted more accurately, faster, and with less reliance upon the operator.

Typically, the article will be a bearing, such as a rolling element bearing.

For a better understanding of the invention, and to show how the same may be put into effect, reference will now be made, by way of example only, to the accompanying drawings in which: Figure 1 shows a prior art arrangement for use by an operator; Figure 2 shows a schematic representation of the steps of the prior art method; and Figure 3 shows an embodiment of the invention.

Figure 1 shows a spherical rolling bearing 1, comprising an inner race 2, which has a conically shaped inner surface, an outer race 3 with a spherical race way, as well as two rows of rollers 4. The spherical roller bearing 1 is being mounted on stub 5, comprising a conically shaped part 6, as well as a screw threaded part 7. A hydraulic nut 8 has been screwed onto the screw threaded part 7. This hydraulic nut 8 comprises a nut body 9 and which has a coaxial annular chamber 10. In said chamber 10 a ring-like piston 11 has been slidingly accommodated. By means of seals 12, the piston 11 has been sealed with respect to the cylindrical walls of chamber 10. By means of connector 13, chamber 10 is connected to a hydraulic hose 14, which in turn is connected to a hydraulic hand pump 15. The oil can be pumped from pump 15 by moving handle 16 up and down. Gauge 17 shows the oil pressure. As shown in Figure 1, piston 11 rests against inner race 2 of spherical roller bearing 1. By pumping oil into chamber 10, ring 2 is driven up the conically shaped part 6 of stub 5. Piston 11 also has a radially outwardly pointing flange 18, against which measuring pin 19 rests. This pin forms part of distance measuring device 20, which contains a screw threaded housing 21 screwed into bore 22 provided in nut body 9. Dial indicator 23 is connected to the axially movable pin 19, so as to enable the measurement of the relative axial displacement between nut body 9 and piston 11.

In the process of mounting the spherical roller bearing 1 onto stub 5, bearing 1, in particular inner race 2 thereof, is slid over stub 5 until the conically shaped surfaces of inner race 2 and stub 5 abut each other. At that position, no or hardly any clamping action exists yet. This position of spherical roller bearing is indicated with A (zero position) in Figure 2. Subsequently, the inner race 2 is driven up to the start position B, by pumping oil into chamber 10 of hydraulic nut 8. Once the start position B has been reached, the inner race 2 is driven up over a distance Ss towards final position C. With reference S, the distance between the position wherein the bearing is placed by hand, and the final position has been indicated.

Figure 3 shows an embodiment of a system of the invention comprising a hydraulic nut 100, a pump 115, and a remote control device 200. In Figure 3, items similar to those of Figure 1 have been shown with the same reference numerals.

The pump 115 may be a hand pump, a power-assisted pump and/or an electrically-operated pump.

The hydraulic nut 100 is arranged to be fixedly mounted on the shaft, for example by being clamped to the shaft, or by being screwed onto a thread on the shaft.

The hydraulic nut 100 comprises a nut body 9 which has a coaxial annular chamber 10. In said chamber 10 a ring-like piston 11 has been slidingly accommodated. Preferably, seals 12 are provided to seal the piston 11 with respect to the cylindrical walls of chamber 10.

Chamber 10 is connected to a hydraulic or pneumatic hose 14, which is connected to the pump 115. Fluid can be pumped from pump 115 into the chamber 10 via the hose 14.

The hydraulic nut 100 may comprise an electric pressure sensor 117 to provide an electrical signal indicative of the pressure within chamber 10. The pressure sensor 117 may communicate wirelessly with other devices via wireless pressure transmitter 118. Preferably, wireless pressure transmitter 118 can communicate with other devices via Bluetooth.

Whilst the pressure sensor 117 and optional wireless transmitter 118 of this embodiment form part of the hydraulic nut 100, they may instead be provided as part of the pump 115 (since the pumping pressure represents the pressure in chamber 10), or as a separate device attached to the hose 14.

The pump 115 is arranged to pump fluid into chamber 10. This can provide force to drive ring 2 up the conically shaped part 6 of stub 5. The pump 115 may communicate wirelessly with other devices via wireless pump receiver 116. Preferably, wireless pump receiver 116 can receive commands by which to control the pump 115 using other devices. Preferably, wireless pump receiver 116 can communicate with other devices via Bluetooth.

In embodiments in which the pressure sensor 117 forms part of the pump 115, wireless pump receiver 116 and wireless pressure transmitter 118 may be a single communications device.

The hydraulic nut 100 comprises an electric distance measuring device 120 to provide an electrical signal indicative of the displacement of the piston 11 within chamber 10. The distance measuring device 120 may communicate wirelessly with other devices via wireless displacement transmitter 125. Preferably, wireless displacement transmitter 125 can communicate with other devices via Bluetooth.

A remote control device 200 comprises: a display 205; a communication device 210; and input means 225. In some embodiments, the display 205 and input means 225 are provided collectively as a touch-screen 205, 225.

The input means 225 is arranged to receive a user's input, which may be used to control the pump 115.

The communications device 210 is configured to wirelessly receive signals from the wireless pressure transmitter 118 and the wireless displacement transmitter 125. Preferably, the communications device 210 is configured to provide wireless control signals to the wireless pump receiver 116 for controlling the pump 115. For example, the communications device 210 can send user commands obtained from the input means 225 to the pump 115 for control thereof, e.g. to turn the pump on or off.

The display 205 is configured to display an indicium representing the signals received by the communications device from the pressure transmitter 118 and the wireless displacement transmitter 125.

The remote control device 210 can be configured to display first information representing pressure in the chamber 10 and second information representing displacement of the piston 11.

Preferably, the remote control device 200 comprises a memory for storing data. The data may be inputted via the input means 225 or, alternatively, these may be accessed from a remote server.

The data may include one or more of: the mounting arrangement (e.g., whether with or without sleeve, and the sleeve type); the type of hydraulic nut; the bearing type; the clearance reduction; the number of previous mountings; the shaft material; and/or the shaft bore size (if applicable).

Whilst in some embodiments, the inputted or accessed data may include the desired pressures and displacements for one or more types of article, in other embodiments, the desired pressure and displacement may be calculated using the remote control device 200 from the inputted or accessed data.

In some embodiments, the display 205 displays both the first information and the second information.

The indicator may vary in dependence upon the current pressure, initial pressure, and desired pressure, or in dependence upon current displacement, initial displacement, and desired displacement. In this way the indicator can represent either quantity in a simple, accurate and easily interpreted manner. Advantageously, this removes the burden from the operator of making reference to tables to determine how to operate the pump 115.

In general, the indicator may indicate the proportion of a range from an initial value to a desired value achieved by the pump 115 and hydraulic nut 100, irrespective of whether this is a pressure or a displacement.

In some embodiments, a first mode is provided in which the display 205 displays the first information and does not display the second information, and a second mode is provided in which the display 205 displays the second information and does not display the first information. Optionally, the display 205 may automatically switch from the first mode to the second mode (i.e., without requiring operator intervention). In such embodiments, the remote control device 210 may be configured to display a single indicator, which can represent the first information in the first mode and the second information in the second mode.

In some embodiments, the indicator is arranged to indicate the proportion of a range from an initial value of pressure to a desired value of pressure when the pressure is between the initial value of pressure and the desired value of pressure. Once the desired pressure has been achieved, the indicator can cease to indicate the proportion of pressure, and instead indicate the proportion of a range from an initial value of displacement to a desired value of displacement.

The indicator may be, for example, a progress bar that fills or a traffic light that turns from red to amber to green.

In preferred embodiments, the indicator is arranged to indicate the progress of the entire mounting procedure (i.e. both the stage of achieving the desired pressure and the subsequent stage of achieving the desired displacement). The operator may continue to actuate the pump 115 (whether by manual actuation, or electrically via the input means 225) until the indicator indicates the process has been completed. With such an indicator it may not be visible to the operator which stage (whether achieving the desired pressure or desired displacement) is currently being carried out.

Preferably, the indicator represents the progress such that the first half of the progression is from the initial value of pressure to the desired value of pressure and the second half of the progression is from the initial value of displacement to the desired value of displacement. In which case, the desired value of pressure will correspond with the initial value of displacement.

As a first example, the indicator may be a graphical representation of a bar that fills as the procedure progresses, in which the first half of the bar represents a range from the initial value of pressure to the desired value of pressure and the second half of the bar indicates the proportion of a range from the initial value of displacement to the desired value of displacement.

As a second example, the indicator may be a coloured representation that changes colour through a predetermined sequence of colour from a start colour via intermediate colours to an end colour (e.g. from green to amber to red -the standard "traffic light" colours) as the procedure progresses. The start colour (e.g. green) may represent the initial value of pressure, the intermediate colour (e.g. amber) may represent the desired value of pressure and the initial value of displacement, and the final colour (e.g. red) may represent the desired value of displacement.

An operator may use the indicator displayed on the display 205 to establish when and how to actuate the pump 115 (whether by manual actuation, or electrically via the input means 225).

In a second embodiment, the system is configured such that the process of mounting an article, such as a bearing, can be triggered by a single start command issued by an operator, for example, via input means 225.

For example, an operator would slide the article 1 over a conical shaft 5 until the conically shaped surfaces of the inner surface of the bore through the article 1 and the outer surface of the shaft 5 abut each other. At that position, there will be no or hardly any significant clamping action. The operator can then mount the hydraulic nut 100 on the shaft 5. This position of the article 1 is indicated with A (zero position) in Figure 2.

The operator may then issue the start command, in response to which the remote control device 200 may be programmed to carry out the following steps: (1) Transmit a control signal to activate the pump 115. The control signal may be transmitted from the communications device 210 to the wireless pump receiver 116.

(2) Receive a pressure signal from the wireless pressure transmitter 118 using the communications device 210.

(3) Compare the received pressure signal with a pressure threshold. The pressure threshold can be either a threshold stored on the remote control device 210 or obtained from a remote server.

(4) When the received pressure signal reaches the pressure threshold, receive a first displacement signal from the wireless displacement transmitter 125. Indeed, the distance measuring device 120 may be inactive until this stage and only activated once the pressure threshold has been achieved. Similarly, the pressure sensor 117 may be deactivated when the threshold is reached. (Such communications may be effected via transmitters 116 and 125, which may also be receivers).

(5) Calculate a displacement threshold. This may be calculated, for example, by adding a desired displacement (Ss in Figure 2) to the present displacement as indicated by the first displacement signal. The desired displacement can be either a threshold stored on the remote control device 210 or obtained from a remote server.

(6) Receive a further displacement signal (or continue to receive the same signal) from the wireless displacement transmitter 125. Once the pressure threshold has been achieved, the wireless displacement transmitter 125 may continue to transmit displacement signals.

(7) Compare the received further displacement signal with the displacement threshold.

(8) When the received displacement signal reaches the displacement threshold, transmit a control signal to deactivate the pump 115. The control signal may be transmitted from the communications device 210 to the wireless pump receiver 116.

(9) Provide an output signal (e.g. audibly, or via the display 205) after a predetermined amount of time. The predetermined amount of time can be either a threshold stored on the remote control device 210 or obtained from a remote server.

In response to step (1), the pump 115 will pump fluid into chamber 10 of hydraulic nut 100, thereby driving article 1 up to the start position B. Following step (4), position B will have been reached. Following step (8), the article 1 will have been driven up over a distance Ss and reached final position C. Between steps (8) and (9), any lubricant between the article 1 and the shaft 5 will egress.

Claims

CLAIMS: 1. A system for mounting a hollow component on a shaft, comprising: a hydraulic nut (100) having an annular coaxial cavity (10) and a ring like piston (110), displaceable within the cavity (10); a displacement sensor (120) for providing a displacement signal indicating the axial displacement of the piston (11) within the cavity (10); a wireless displacement transmitter (125) for transmitting the displacement signal; a pressure sensor (117) for providing a pressure signal indicating a pressure within the cavity (10); a wireless pressure transmitter (118) for transmitting the pressure signal; a pump (115) arranged to pump fluid into the chamber (10); and a remote display device (200) having a communications device (210) arranged to receive transmitted pressure and displacement signals and a display arranged to display one or more of: the sensed pressure; the sensed displacement; the proportion of a range from an initial value of pressure to a desired value of pressure; and/or the proportion of a range from an initial value of displacement to a desired value of displacement.
2. The system of claim 1, wherein the display is arranged to display the progress of a method from a start point via an intermediate point to a finish point, the method involving an increase in pressure from an initial value of pressure to a desired value of pressure followed by an increase in displacement from an initial value of displacement to a desired value of displacement, wherein: the start point corresponds to an initial value of pressure sensed by the pressure sensor (117); the intermediate point corresponds to a desired value of pressure sensed by the pressure sensor (117) and an initial value of displacement sensed by the displacement sensor (120); and the final point corresponds to a desired value of displacement sensed by the displacement sensor (120).
3. The system of claim 2, wherein the display represents the progress using one or more of: a graphical representation of a progress bar that fills up as the method progresses; and/or a coloured indicia that changes colour as the method progresses.
4. The system of claim 1, wherein the display is arranged to display the proportion of a range from an initial value of pressure to a desired value of pressure when the pressure is between the initial value of pressure and the desired value of pressure, and then the proportion of a range from an initial value of displacement to a desired value of displacement.
5. The system of claim 1 or claim 4, wherein the display is arranged to provide a single indicator that indicates one of the proportion of a range from an initial value of pressure to a desired value of pressure and the proportion of a range from an initial value of displacement to a desired value of displacement at a time.
6. The system of claim 1, claim 4 or claim 5, wherein the display is arranged to display the proportion(s) by varying the colour of the/an indicator.