HK1200141B

HK1200141B - Servo motor controlled hydraulic pump unit for tube end forming equipment

Info

Publication number: HK1200141B
Application number: HK15100656.8A
Authority: HK
Inventors: 约翰．弗瑞德瑞克．韦格特
Original assignee: 爱迪生麦基公司
Priority date: 2011-11-11
Filing date: 2012-11-07
Publication date: 2018-09-28

Description

Servo motor controlled hydraulic pump unit for pipe end forming equipment

Technical Field

The present invention relates generally to systems and methods for forming pipe, and more particularly to systems and methods for end forming pipes for use in systems, such as vehicle exhaust systems or other systems that utilize pipes.

Background

Many plumbing applications require pipe end forming. Generally, pipe end forming is used to provide some type of connection to other pipes, hoses, blocks, etc. There are several types of shaping that can be applied to the ends of the tube. These types include reduction, expansion, flaring, beading, impact (or thickening), and the like. One popular process of end forming is referred to as "punch-type end forming". Punch-type end forming is a cold work process by which the pipe to be formed is held firmly in a set of clamping blocks. The forming is completed when one or more end forming tools (e.g., punches) positioned in alignment with the target end of the tube are "punched" or pressed onto the tube end. In addition to or as an alternative to the axial force applied to the target end, an expansion punch may be used to provide radial force to the inner or outer surface of the tube.

To facilitate movement of the forming tools and/or the clamping blocks, end forming machines typically include one or more mechanical actuators. In some machines, hydraulic cylinders are used as actuators. Conventional hydraulic systems for end forming machines utilize an Alternating Current (AC) motor to drive a hydraulic pump so that hydraulic pressure is constantly available to the system. Solenoid operated valves are commonly used to control the actual flow of oil to moving parts of the machine to direct the flow of oil according to the desired machine cycle. The AC motor continuously drives the hydraulic pump even when the machine is not moving and oil pressure and/or flow is not required. As can be appreciated, constant noise, heat and energy usage are all associated with end forming machines that use conventional hydraulic power units.

Drawings

Fig. 1 depicts a block diagram of a pipe end forming machine including a servo motor controlled hydraulic pump unit according to one embodiment of the present invention.

Figure 2 depicts a cross-sectional view showing a first stage in the process of forming an enlarged end on a tube, wherein the tube is positioned between open gripper blocks.

Figure 3 depicts a cross-sectional view showing a second stage of the process of forming an enlarged end on a pipe, wherein the pipe is fixedly clamped between clamping blocks.

Fig. 4 depicts a cross-sectional view showing a third stage of the process of forming an enlarged end portion on a tube, wherein an expansion punch has entered the end of the tube and has expanded it to form an expanded end portion.

Fig. 5 depicts a cross-sectional view showing a fourth stage of the process of forming an enlarged end on a pipe, where the expansion punch has been withdrawn from the end of the pipe and the pipe has been released from the clamping block.

Detailed Description

Embodiments of the present invention are directed to systems and methods for providing a pipe-end forming apparatus or machine that takes advantage of hydraulic power without the constant noise, heat and energy usage associated with conventional hydraulic power units. Embodiments of the present invention are designed such that the hydraulic pump unit is only operated when there is a demand for oil pressure/flow from the system. In some embodiments, this is accomplished by providing a synchronous servo motor and servo drive coupled to a hydraulic pump (e.g., a fixed or variable displacement hydraulic pump). The oil pressure of the system is monitored to detect when the pressure drops below a preset value to provide closed loop control of the servo motor. The servo motor is controlled to rotate the hydraulic pump at the required speed (up to the maximum RPM of the motor/pump combination) as necessary to achieve the required system pressure.

Referring to fig. 1, there is shown one embodiment of a pipe-end forming machine 10 including a hydraulic pump unit 12 controlled by a servo motor 14 (e.g., a synchronous servo motor). The end forming machine 10 includes a servo drive 16 operable to provide power to the servo motor 14 and control its rotational speed and/or torque. The servo motor 14 provides rotational motion to the hydraulic pump unit 12 based on control signals received from the servo driver 16.

In some embodiments, hydraulic pump unit 12 is a fixed displacement hydraulic pump configured to generate oil flow and/or pressure in a hydraulic circuit that includes an actuator 18 (e.g., a hydraulic cylinder) coupled to hydraulic pump unit 12 by a hydraulic valve 20. In other embodiments, a variable displacement hydraulic pump may be used. The variable speed and/or torque of the servo motor 14 controls the flow rate and pressure of the hydraulic circuit of the end forming machine 10. As shown in fig. 1, the actuator 18 is operatively coupled to the end forming tool 22 and is operable to provide physical movement (e.g., axial movement) of the end forming tool to change the shape of the end of the tube ("tube end"). In some embodiments, additional hydraulic valves 24 and 26 may be provided that are similarly coupled to the hydraulic pump unit 12 and other actuators and end forming tools used with the end forming machine 10.

The end forming machine 10 also includes a controller 28, such as a Programmable Logic Controller (PLC) (e.g., a digital computer), which is operable to control the sequence of operations for the end forming process and the position of the end forming tool 22 (see fig. 2-5). The controller 28 is also configured to optimize hydraulic pressure and flow for the end forming process and reduce or eliminate power usage, heat generation, and noise generation by reducing or eliminating oil flow when not needed. In this regard, the controller 28 is operable to provide an indication of the system pressure requirement to the servo drive 16 and control commands to the hydraulic valves 20 (and, in use, the hydraulic valves 24 and 26) to control the flow of oil delivered to and from the actuator 18. Controller 28 is operatively coupled to servo drive 16 and hydraulic valve 20 by communication lines 30 and 32, respectively. Controller 28 also receives position feedback information from actuator 18 via communication line 34, which allows the controller to precisely control the end-forming process.

The end forming machine 10 also includes a pressure transducer 36 (or sensor) positioned in the hydraulic circuit between the hydraulic pump unit 12 and the hydraulic valve 20. The pressure transducer 36 is configured to monitor the hydraulic pressure in the system during operation. Pressure transducer 36 is operatively coupled to servo drive 16 by a feedback communication line 38 and is configured to provide pressure feedback information to the servo drive. Using feedback information received from the pressure transducer 38, the servo drive 16 is operable to adjust the speed and/or torque of the servo motor 14 as needed to maintain the hydraulic pressure required by the controller 28 to control the end-forming process.

Fig. 2-5 illustrate various stages of a pipe-end forming process that may be carried out on a pipe 50 using the end forming machine 10 of fig. 1 described above to expand an end 52 of the pipe. Referring first to fig. 2, the actuator 18 takes the form of a hydraulic cylinder-piston arrangement 54 including a working cylinder 56 including a cylindrical body portion 58 having left and right end portions 60 and 66, respectively, forming a cylindrical interior volume divided by a piston member 64. The piston member 64 is freely movable in the left and right axial directions, as shown in fig. 2 to 5. A piston member 64 is coupled to or integrally formed with the piston rod 62, the piston member extending axially from the piston member 64 in a direction toward a right end portion 66 of the working cylinder 56. The piston member 64 projects to the right in fig. 2 to 5 beyond a right end portion 66 of the working cylinder 56.

The piston member 64 defines two working pressure chambers: a first pressure chamber 68 between the left end 70 of the piston member 64 and the left end portion 60 of the cylinder 56, and a second pressure chamber 72 between the right end 74 of the piston member and the right end portion 66 of the cylinder 56. Hydraulic fluid (e.g., oil) may be selectively supplied to the first pressure chamber 68 through a hydraulic fluid port or passage 76 such that the piston member 64 is driven to the right in fig. 2-5 with the piston rod 62 when hydraulic fluid is supplied to the first pressure chamber. Similarly, hydraulic fluid may be selectively supplied to the second pressure chamber 72 through a hydraulic fluid port or passage 78 such that the piston member 64 is driven to the left with the piston rod 62 when hydraulic fluid is supplied to the second pressure chamber. The hydraulic fluid passages 76 and 78 are operatively coupled to hydraulic pumps and valves, such as the hydraulic pump 12 and the hydraulic valve 20 shown in FIG. 1.

In fig. 2-5, the end forming tool 22 of fig. 1 takes the form of an end forming tool 80 that is selectively coupled to the right end of the piston rod 62. The end forming tool 80 includes an expansion punch 82 that extends rightward (as viewed) from the end forming tool in a manner such that the expansion punch is coaxial with the piston rod 62. The expansion punch 82 is provided with a tapered portion 84 at its top end and has a diameter D equal to the desired enlarged internal diameter of the end 52 of the tube 50_E. It should be understood that the end portionsThe forming tool 80 may include other types of punches including, but not limited to, reducing punches, swaging punches, flaring punches, and capping punches.

As shown in fig. 2, piston member 64 is initially moved to the left by supplying hydraulic fluid to second pressure chamber 72 through hydraulic fluid passage 78. The tube 50 is positioned in the clamp 86 between an upper clamp block 88 and a lower clamp block 90. As shown in fig. 3, the upper 88 and lower 90 clamping blocks are moved relative to each other into a position in which the tubular 50 is secured in the clamp 86 between the clamping blocks and axially aligned with the expansion punch 82.

Next, as shown in fig. 4, hydraulic fluid under pressure is supplied to first pressure chamber 68 through hydraulic fluid passage 76, the supply of hydraulic fluid under pressure to second pressure chamber 72 has been stopped and the fluid therein is free to drain through hydraulic fluid passage 78. This action causes the piston member 64 to be driven to the right, causing the expansion punch 82 to enter the end 52 of the tube 50 and expand the tube 50 as the punch moves, causing an expanded portion 92 to be formed in the end of the tube.

When the expansion ram 82 has been inserted into the end 52 of the tube 50 by the desired amount, the supply of hydraulic fluid to the first pressure chamber 68 is stopped and hydraulic fluid under pressure is supplied to the second pressure chamber 72, wherein the fluid in the first pressure chamber is free to drain through the hydraulic fluid passage 76. Thus, as shown in fig. 5, the piston member 64 is withdrawn to the left and the expansion punch 82 is completely withdrawn from the end 52 of the tube 50. As a result of this process, a belt with an expanded diameter D is produced_EThe tube 50 of the expanded portion 92.

Table 1 below compares the operating conditions of an end-forming machine utilizing a servo motor controlled hydraulic pump unit under four different machine conditions with a conventional hydraulic end-forming machine using an AC motor.

TABLE 1

Machine state	Servo/pump state	Conventional pump condition
			The machine is idle	Not rotating	Full RPM
Actuator movement at 50% speed	50% maximum RPM	Full RPM
			Actuator movement at 100% speed	Maximum RPM of 100%	Full RPM
Actuator holding pressure	RPM required to overcome any system losses	Full RPM

As shown in table 1 above, when the end forming machine is in an idle condition, the servo motor (e.g., servo motor 14 of fig. 1) is not rotating, rotates at 50% of maximum RPM when the actuator (e.g., hydraulic cylinder) is moving at 50% speed, and rotates only at the RPM required to overcome any system losses (i.e., very slow RPM) when the actuator is holding pressure and is not moving. In contrast, the pump units used in conventional end forming machines are constantly running at full RPM, regardless of the operating state of the machine.

The embodiments disclosed herein allow for control of the oil flow rate and hence the speed of the actuator by enhancing mechanical motion control using variable speed of the servo motor/pump arrangement. This is in contrast to conventional hydraulic end forming machines, in which oil flows from the valve ports at the full flow rate available (as permitted by the valve port size and fluid lines). To accomplish this reduction in movement speed for these conventional machines, restrictions in the form of flow control valves must be placed into the fluid lines to reduce the oil flow rate and thus slow machine movement. While this approach does achieve the desired speed control, the restriction introduced into the fluid line generates heat as a byproduct of the fluid line restriction, resulting in higher energy consumption and higher heat generation.

Embodiments of the present invention also allow for enhanced operator safety. Since the hydraulic pump unit does not produce pressure or flow when not needed, the end forming machine is naturally in a low energy state when the machine is at rest. This can only be done on conventional systems by using block valves and/or vent valves in the circuit, which is not expected to cause additional heat and noise emissions.

It will be appreciated that embodiments of the present invention provide several advantages to an end forming machine that utilizes a conventional hydraulic circuit and an AC motor. That is, the embodiments disclosed herein use less energy and require less hydraulic system maintenance due to the significantly reduced duty cycle on the hydraulic pump unit, both of which reduce operating costs. The embodiments presented herein also generate less heat, generate less noise emissions, require a smaller hydraulic tank and therefore less oil to operate, have the ability to control the speed of machine action without additional components in the hydraulic circuit, and achieve a safe, low energy state when the machine is idle without additional components in the hydraulic circuit (which can increase cost and thermal noise and emissions).

The embodiments described above depict different other components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented (which can achieve the same functionality). In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being "operably connected," or "operably coupled," to each other to achieve the desired functionality.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from this invention and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention.

Furthermore, it is to be understood that the invention is solely defined by the appended claims. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) generally mean "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.).

It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an recitation is not intended to be explicitly recited in the claim, and in the absence of such recitation no such recitation is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrasesShould not be construed asThe introduction of a claim statement by the indefinite article "a" or "an" limits any particular claim containing such introduced claim statement to inventions containing only one such statement, even if the sameThe claims hereof include the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); as well as the use of definite articles for introducing claim recitations.

Claims

1. An apparatus for changing the shape of an end of a tube using an end forming tool, the apparatus comprising:

a hydraulic actuator operatively coupled to the end forming tool and configured to move the end forming tool into contact with the end of the tube to change its shape;

a hydraulic pump operatively coupled to the hydraulic actuator through a hydraulic circuit including a hydraulic valve and a hydraulic fluid, the hydraulic circuit configured to drive the hydraulic actuator;

a servo motor operably coupled to the hydraulic pump and configured to drive the hydraulic pump to pressurize hydraulic fluid in the hydraulic pump;

a servo drive coupled to the servo motor and operable to control a speed or torque of the servo motor, which in turn controls a flow rate or pressure of the hydraulic fluid in the hydraulic circuit;

a pressure transducer operatively coupled to the hydraulic circuit and the servo drive, the pressure transducer configured to monitor a hydraulic pressure of hydraulic fluid in the hydraulic circuit and provide pressure feedback information indicative of the measured hydraulic fluid pressure to the servo drive; and

a controller operatively coupled to the servo drive, the hydraulic valve, and the hydraulic actuator, the controller configured to control a flow of pressurized hydraulic fluid between the hydraulic valve and the hydraulic actuator by receiving position feedback information from the hydraulic actuator and sending (1) a valve control command to the hydraulic valve; and sending (2) a servo control signal indicative of a target hydraulic fluid pressure of the hydraulic pump to the servo drive to control the position and movement of the end forming tool, the servo drive configured to control a speed or torque of the servo motor in response to receiving the pressure feedback information and the servo control signal.

2. The apparatus of claim 1, wherein the servo motor is a synchronous servo motor.

3. The apparatus of claim 1, wherein the hydraulic pump is a fixed displacement hydraulic pump.

4. The apparatus of claim 1, wherein the hydraulic valve is positioned in the hydraulic circuit between the hydraulic pump and the hydraulic actuator, the hydraulic valve operable to control a direction of flow of the hydraulic fluid through the hydraulic circuit.

5. The apparatus of claim 1, further comprising a plurality of hydraulic actuators and a plurality of hydraulic valves, wherein each of the hydraulic valves is positioned in the hydraulic circuit between the hydraulic pump and a corresponding one of the plurality of hydraulic actuators, each of the hydraulic valves configured to control a flow of hydraulic fluid to and from the hydraulic valve corresponding to one of the hydraulic actuators.

6. The apparatus of claim 1, wherein the hydraulic actuator comprises a hydraulic cylinder-piston arrangement including a working cylinder, a piston member, and a piston rod coupled to the piston member, the piston rod being removably coupled to the end forming tool.

7. An apparatus for changing the shape of an end of a tube using an end forming tool, the apparatus comprising:

a hydraulic cylinder-piston device operatively coupled to the end forming tool and configured to move the end forming tool into contact with the end of the pipe to change its shape;

a fixed displacement hydraulic pump operatively coupled to the cylinder-piston arrangement through a hydraulic circuit including hydraulic valves and hydraulic fluid, the hydraulic circuit configured to drive the cylinder-piston arrangement;

a synchronous servo motor operably coupled to the fixed displacement hydraulic pump and configured to pressurize hydraulic fluid in the fixed displacement hydraulic pump;

a servo drive coupled to the synchronous servo motor and operable to control a speed or torque of the synchronous servo motor, which in turn controls a flow rate or pressure of the hydraulic fluid in the hydraulic circuit;

a pressure transducer operatively coupled to the hydraulic circuit and the servo drive, the pressure transducer configured to monitor a hydraulic pressure of hydraulic fluid in the hydraulic circuit and provide pressure feedback information indicative of the measured hydraulic fluid pressure to the servo drive, a hydraulic valve positioned in the hydraulic circuit positioned between the fixed displacement hydraulic pump and the cylinder-piston arrangement, the hydraulic valve operable to control a direction of flow of the hydraulic fluid through the hydraulic circuit; and

a digital computer operably coupled to the servo drive, the hydraulic valve, and the cylinder-piston arrangement, the digital computer configured to control the position and movement of the end forming tool by receiving position feedback information from the cylinder-piston arrangement, sending a servo control signal to the servo drive indicative of a target hydraulic fluid pressure of a fixed displacement hydraulic pump, and sending a valve control command to the hydraulic valve to control the direction of flow of pressurized hydraulic fluid through the hydraulic circuit, the servo drive configured to control the speed or torque of a synchronous servo motor in response to receiving the pressure feedback information and the servo control signal.

8. A method for changing the shape of an end of a tube, the method comprising:

providing a pipe end forming machine comprising:

an end forming tool;

a servo motor operably coupled to the hydraulic pump and configured to drive the hydraulic pump to pressurize hydraulic fluid in the hydraulic pump; and

controlling the position and movement of the end forming tool by performing the steps of:

monitoring a hydraulic pressure of a hydraulic fluid in the hydraulic circuit;

in response to monitoring the hydraulic pressure of the hydraulic fluid, sending pressure feedback information indicative of the measured hydraulic fluid pressure to the servo drive;

receiving position feedback information from the hydraulic actuator;

sending a servo control signal indicative of a target hydraulic fluid pressure of a hydraulic pump to the servo drive;

controlling a speed or torque of the servo motor in response to receiving the pressure feedback information and the servo control signal;

the direction of flow of pressurized hydraulic fluid between the hydraulic valve and the hydraulic actuator is controlled by sending a valve control command to the hydraulic valve.

9. The method of claim 8 wherein the servo motor of the tube end forming machine is a synchronous servo motor.

10. The method of claim 8, wherein the hydraulic pump of the pipe-end forming machine is a fixed displacement hydraulic pump.

11. The method of claim 8, wherein the hydraulic valve is positioned in the hydraulic circuit between the hydraulic pump and the hydraulic actuator, and the method further comprises controlling operation of the hydraulic valve to control a direction of flow of the hydraulic fluid through the hydraulic circuit.

12. The method of claim 8, wherein the pipe-end forming machine further comprises a plurality of hydraulic actuators and a plurality of hydraulic valves, wherein each of the hydraulic valves is positioned in the hydraulic circuit between the hydraulic pump and a corresponding one of the plurality of hydraulic actuators, the method further comprising controlling operation of the plurality of hydraulic valves to control the flow of hydraulic fluid to and from each of the plurality of hydraulic actuators.

13. The method of claim 8, wherein the hydraulic actuator of the pipe-end forming machine comprises a hydraulic cylinder-piston device including a working cylinder, a piston member, and a piston rod coupled to the piston member, the pipe-end forming machine being removably coupled to the piston rod.

14. The method of claim 8, wherein the end forming tool comprises an expansion punch.

15. A method for changing the shape of an end of a tube, the method comprising:

providing a pipe end forming machine comprising:

an end forming tool;

a servo drive coupled to the synchronous servo motor and operable to control a speed or torque of the synchronous servo motor, which in turn controls a flow rate or pressure of the hydraulic fluid in the hydraulic circuit; and

a hydraulic valve positioned in the hydraulic circuit between the fixed displacement hydraulic pump and the cylinder-piston arrangement, the hydraulic valve operable to control a direction of flow of the hydraulic fluid through the hydraulic circuit;

measuring a hydraulic pressure of a hydraulic fluid in the hydraulic circuit;

in response to measuring the hydraulic pressure of the hydraulic fluid, sending pressure feedback information indicative of the measured hydraulic fluid pressure to the servo drive;

receiving position feedback information from the cylinder-piston assembly;

controlling a speed or torque of the servo motor in response to receiving the pressure feedback information and the servo control signal; and

the direction of flow of pressurized hydraulic fluid in the hydraulic circuit is controlled by sending valve control commands to hydraulic valves.