阅读说明：本技术 一种全伺服机器人弯管机 (Full-servo robot pipe bending machine ) 是由 李聪 黄万永 刘坤 吴钰屾 周兵 王财先 于 2021-08-02 设计创作，主要内容包括：本发明公开了一种全伺服机器人弯管机,涉及到零件加工技术领域,包括安装座以及设于安装座上的弯管转臂模块、主夹模块、导夹模块、导夹随动模块和弯管模具,其中,主夹模块安装在弯管转臂模块上,且弯管转臂模块可驱动主夹模块绕Z轴方向旋转,主夹模块上设有主夹模具,导夹模块上设有导夹模具,主夹模具和导夹模具分别与弯管模具连接,且主夹模具和导夹模具分别用于弯管模具Y方向的夹紧固定,导夹随动模块与导夹模具连接,用于控制导夹模具沿X方向运动。本发明中的弯管机,可配合机器人完成弯管折弯,采用伺服电机进行弯管夹紧、折弯以及弯管时跟随,可实现高精度弯管。(The invention discloses a full-servo robot pipe bending machine, which relates to the technical field of part processing and comprises a mounting seat, a pipe bending rotating arm module, a main clamp module, a guide clamp follow-up module and a pipe bending die, wherein the pipe bending rotating arm module, the main clamp module, the guide clamp follow-up module and the pipe bending die are arranged on the mounting seat, the main clamp module is arranged on the pipe bending rotating arm module, the pipe bending rotating arm module can drive the main clamp module to rotate around the Z-axis direction, a main clamp die is arranged on the main clamp module, the guide clamp die is arranged on the guide clamp module, the main clamp die and the guide clamp die are respectively connected with the pipe bending die, the main clamp die and the guide clamp die are respectively used for clamping and fixing the pipe bending die in the Y direction, and the guide clamp follow-up module is connected with the guide clamp die and is used for controlling the guide clamp die to move along the X direction. The pipe bending machine can be matched with a robot to finish pipe bending, adopts the servo motor to clamp and bend pipes and follow the pipes during pipe bending, and can realize high-precision pipe bending.)

1. The utility model provides a full servo robot bending machine, its characterized in that, includes the mount pad and locates return bend rocking arm module, main clamp module, leads on the mount pad and press from both sides the module, lead and press from both sides follow-up module and bending die utensil, wherein, main clamp module is installed on the return bend rocking arm module, just return bend rocking arm module can drive main clamp module is rotatory around Z axle direction, be equipped with main clamp mould in the main clamp module, it presss from both sides the mould to lead to be equipped with on the clamp module, main clamp mould with lead press from both sides the mould respectively with the bending die utensil is connected, just main clamp mould with it is used for respectively to lead press from both sides the mould the clamp of bending die utensil Y direction is tight fixed, lead press from both sides follow-up module with lead to press from both sides the mould and connect, be used for control it moves along X direction to lead to press from both sides the mould.

2. The full-servo robot pipe bender according to claim 1, wherein the pipe bending tumbler module comprises a pipe bending motor, a first speed reducer, a first transition flange and a first rotation shaft, the pipe bending motor is disposed at the upper end of the mounting base, the lower end of the pipe bending motor is connected to the first speed reducer through the first transition flange, the first rotation shaft is disposed at the lower end of the mounting base, one end of the first rotation shaft is connected to the first speed reducer, and the main clamp module is mounted on the first rotation shaft.

3. The full-servo robotic bender according to claim 2, further comprising a second transition flange disposed on said first rotation axis, wherein said second transition flange is located at a lower side of said main clamp module, and another end of said first rotation axis is connected to said bending mold.

4. The full servo robotic bender according to claim 1, wherein said main clamp module comprises:

a first clamping motor;

the second speed reducer is in driving connection with the first clamping motor;

one end of the second rotating shaft is connected with the second speed reducer;

one end of the screw rod is in transmission connection with the second rotating shaft;

the first sliding block is arranged on the first lead screw, and the main clamp die is connected with the first sliding block.

5. The full servo robotic bender according to claim 4, further comprising a first gear and a second gear, said first gear being connected to said rotary shaft, said second gear being connected to one end of said first lead screw, said first gear being in meshing engagement with said second gear.

6. The full-servo robotic bender according to claim 4, wherein said first clamping motor and said second reducer are disposed at an upper end of said mounting base, and said second rotary shaft, said first lead screw, and said first slider are disposed at a lower end of said mounting base, respectively.

7. The full-servo robotic bender according to claim 1, wherein said guide-clamping module comprises a second clamping motor, a third reducer, a third rotation axis, a first pulley, a second pulley, a belt, a second lead screw, and a second slider, said second clamping motor is connected to said third reducer, the second clamping motor and the third speed reducer are both arranged at the upper end of the mounting seat, the third rotating shaft is arranged at the lower end of the mounting seat, one end of the third rotating shaft is connected with the third speed reducer, the first belt pulley is arranged on the third rotating shaft, the second belt pulley is arranged on the second lead screw, and the belt is connected with the first belt pulley and the second belt pulley, the second screw rod is provided with the second sliding block, and the second sliding block is connected with the guide clamp die.

8. The full servo robotic bender according to claim 1, further comprising a robot attachment flange provided on one side of said mounting base, said robot attachment flange for connecting said mounting base to a robot.

9. The full-servo robotic bender according to claim 1, wherein said guide clamp follower module comprises a drive motor disposed at a lower end of said mounting base, said drive motor being configured to drive said guide clamp die to move along an X-direction.

Technical Field

The invention relates to the technical field of part processing, in particular to a full-servo robot pipe bender.

Background

The processing and forming of the bent pipe is one of the processing techniques commonly used in the field of pipe fitting plastic processing, the bent pipe is processed into a bent part with a specific bending radius, bending angle and shape by a certain pipe processing and forming method, and the quality of the bent pipe directly influences the safety, stability and reliability of the product in the fields of ship manufacturing, furniture, bridges, automobile industry and the like.

At present, most of pipe bending equipment adopts a numerical control pipe bending machine or a hydraulic pipe bending machine to bend pipes, the loading and unloading are carried out by manual assistance, the upper and lower procedures can not be completely automated, the production efficiency of the processing technology is low, the required labor cost is high, and the full-automatic production and transformation of the pipes are not facilitated.

Disclosure of Invention

The invention aims to provide a full-servo robot pipe bender for solving the technical problem.

The technical scheme adopted by the invention is as follows:

the utility model provides a full servo robot bending machine, includes the mount pad and locates return bend rocking arm module, main clamp module, lead and press from both sides the module, lead and press from both sides follow-up module and bending die utensil on the mount pad, wherein, main clamp module is installed on the return bend rocking arm module, just return bend rocking arm module can drive main clamp module is rotatory around Z axle direction, be equipped with the main clamp mould on the main clamp module, it leads the clamp mould to be equipped with on the clamp module to lead, the main clamp mould with lead clamp mould respectively with the bending die utensil is connected, just the main clamp mould with lead clamp mould and be used for respectively the tight fixedly of clamp of bending die utensil Y direction, lead press from both sides follow-up module with lead the clamp mould to connect, be used for control it moves along X direction to lead the clamp mould.

Preferably, the elbow/boom module comprises an elbow motor, a first speed reducer, a first transition flange and a first rotating shaft, the elbow motor is arranged at the upper end of the mounting base, the lower end of the elbow motor is connected with the first speed reducer through the first transition flange, the lower end of the mounting base is provided with the first rotating shaft, one end of the first rotating shaft is connected with the first speed reducer, and the main clamp module is arranged on the first rotating shaft.

As a further preference, the bending die further comprises a second transition flange, the second transition flange is arranged on the first rotating shaft and is positioned on the lower side of the main clamping module, and the other end of the first rotating shaft is connected with the bending die.

Preferably, the main clip module includes:

a first clamping motor;

the second speed reducer is in driving connection with the first clamping motor;

one end of the second rotating shaft is connected with the second speed reducer;

one end of the screw rod is in transmission connection with the second rotating shaft;

the first sliding block is arranged on the first lead screw, and the main clamp die is connected with the first sliding block.

Preferably, the gear assembly further comprises a first gear and a second gear, wherein the first gear is connected with the rotating shaft, the second gear is connected with one end of the first lead screw, and the first gear is meshed with the second gear.

Preferably, the first clamping motor and the second speed reducer are arranged at the upper end of the mounting seat, and the second rotating shaft, the first lead screw and the first slider are respectively located at the lower end of the mounting seat.

Preferably, the guide clamping module comprises a second clamping motor, a third speed reducer, a third rotating shaft, a first belt pulley, a second belt pulley, a belt, a second lead screw and a second slider, the second clamping motor is connected with the third speed reducer, the third speed reducer is arranged at the upper end of the mounting seat, the third rotating shaft is arranged at the lower end of the mounting seat, one end of the third rotating shaft is connected with the third speed reducer, the third rotating shaft is provided with the first belt pulley, the second lead screw is provided with the second belt pulley, the belt is connected with the first belt pulley and the second belt pulley, the second lead screw is provided with the second slider, and the second slider is connected with the guide clamping module.

Preferably, the robot connecting device further comprises a robot connecting flange, wherein the robot connecting flange is arranged on one side of the mounting seat and is used for connecting the mounting seat and the robot.

Preferably, the guide clamp follow-up module comprises a driving motor arranged at the lower end of the mounting seat, and the driving motor is used for driving the guide clamp die to move along the X direction. The technical scheme has the following advantages or beneficial effects:

the pipe bending machine can be matched with a robot to finish pipe bending, and a servo motor is adopted to clamp and bend pipes and follow the pipes during pipe bending, so that high-precision pipe bending can be realized; the pipe bending machine can be held by a robot to realize multiple procedures of pipe fitting feeding, pipe bending, blanking and the like, so that the automation degree of pipe bending is greatly improved, and the upgrading and the transformation of an automatic pipe bending production line are facilitated; and secondly, all servo motor control can be controlled by the robot, the robot and a pipe bending machine head are highly integrated, and the robot pipe bending process is perfected.

Drawings

FIG. 1 is a schematic structural view of a full servo robot tube bender according to the present invention;

FIG. 2 is a schematic structural view of a bent pipe tumbler module according to the present invention;

FIG. 3 is a schematic structural view of a main clamp module according to the present invention;

FIG. 4 is a schematic structural view of a clip module according to the present invention;

FIG. 5 is a schematic structural view of a bending mold according to the present invention;

FIG. 6 is a schematic diagram of a robotic automated pipe bending station;

FIG. 7 is a schematic view of an application state of the full servo robot tube bender of the present invention.

In the figure: 1. a full-servo robot pipe bender; 2. a mounting seat; 3. a pipe bending die; 4. a main clamp mold; 5. a guide clamp mould; 6. a pipe bending motor; 601. a first speed reducer; 602. a first transition flange; 603. a first rotating shaft; 604. a second transition flange; 7. a first clamping motor; 701. a second speed reducer; 702. a second rotation shaft; 703. a first lead screw; 704. a first slider; 705. a first gear; 706. a second gear; 8. a second clamping motor; 801. a third speed reducer; 802. a third rotation axis; 803. a first pulley; 804. a second pulley; 805. a belt; 806. a second lead screw; 807. a second slider; 9. a robot connecting flange; 10. a drive motor; 11. a base; 12. a control cabinet; 13. an automatic feeding machine; 14. a pipe bending robot; 15. a blanking frame; 16. rotating the gripper; 17. a main clamp module; 18. the pipe fitting auxiliary supporting mechanism; 19. the pipe fitting auxiliary supporting mechanism cabinet; 20. a robot guide rail.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that, as the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, their indicated orientations or positional relationships are based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" as appearing herein are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" should be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

FIG. 1 is a schematic structural view of a full servo robot tube bender according to the present invention; FIG. 2 is a schematic structural view of a bent pipe tumbler module according to the present invention; FIG. 3 is a schematic structural view of a main clamp module according to the present invention; FIG. 4 is a schematic structural view of a clip module according to the present invention; FIG. 5 is a schematic structural view of a bending mold according to the present invention;

fig. 6 is a schematic structural diagram of a robotic automatic pipe bending workstation, please refer to fig. 1 to 6, which illustrate a preferred embodiment, showing a full servo robotic pipe bender 1, comprising a mounting base 2, and a pipe bending rotating arm module, a main clamp module 17, a guide clamp module, a guide clamp follower module and a pipe bending mold 3 arranged on the mounting base 2, wherein, the main clamping module 17 is arranged on the elbow arm module of the elbow, and the elbow arm module of the elbow can drive the main clamping module 17 to rotate around the Z-axis direction, the main clamping module 17 is provided with a main clamping mould 4, the guide clamping module is provided with a guide clamping mould 5, the main clamping mould 4 and the guide clamping mould 5 are respectively connected with the elbow mould 3, and the main clamp die 4 and the guide clamp die 5 are respectively used for clamping and fixing the bending die 3Y direction, and the guide clamp follow-up module is connected with the guide clamp die 4 and used for controlling the guide clamp die 5 to move along the X direction. In this embodiment, as shown in fig. 1, the pipe bending tumbler module is configured to drive the main clamp module 17 to rotate around the Z-axis direction to realize a pipe bending action, the main clamp module 17 is configured to control the main clamp mold 4 to clamp and fix the pipe bending mold 3, the clamp guiding module is configured to control the clamp guiding mold 5 to clamp and fix the pipe bending mold 3, and the pipe bending mold 3 is configured to connect a pipe bending. When the pipe bending die 3 rotates, the guide clamp follow-up module can be used for driving the guide clamp die 5 to perform X-direction follow-up motion. In the present embodiment, the main clamp die 4 can rotate together with the main clamp block 17 about the Z-axis direction. The pipe bender in the embodiment is used for being installed on an arm of a robot and is controlled by the robot. The main clamp mold 4 and the guide clamp mold 5 in this embodiment are both installed at the lower end of the installation base 2.

Further, as a preferred embodiment, the elbow/boom module includes an elbow motor 6, a first speed reducer 601, a first transition flange 602, and a first rotating shaft 603, the elbow motor 6 is disposed at the upper end of the mounting base 2, the lower end of the elbow motor 6 is connected to the first speed reducer 601 through the first transition flange 602, the lower end of the mounting base 2 is provided with the first rotating shaft 603, one end of the first rotating shaft 603 is connected to the first speed reducer 601, and the main clamp module 17 is mounted on the first rotating shaft 603. In this embodiment, the output shaft of the bending motor 6 is decelerated by the first speed reducer 601 and controls the first rotating shaft 603 to rotate, the first speed reducer 601 is provided to stabilize the rotating speed of the first rotating shaft 603, and the first rotating shaft 603 is used to control the main clamp module 17 to rotate.

Further, as a preferred embodiment, the bending die further includes a second transition flange 604, the second transition flange 604 is disposed on the first rotating shaft 603, the second transition flange 604 is located at the lower side of the main clamping module 17, and the other end of the first rotating shaft 603 is connected to the bending die 3. In this embodiment, when the first rotating shaft 603 rotates, the bending mold 3 also rotates, wherein the bending mold 3 is connected to the first rotating shaft 603 through the second transition flange 604, and the second transition flange 604 can facilitate the installation and detachment of the bending mold 3.

Further, as a preferred embodiment, the main clamp module 17 includes:

a first clamping motor 7;

the second speed reducer 701, the second speed reducer 701 is connected with the first clamping motor 7 in a driving way;

a second rotation shaft 702, one end of the second rotation shaft 702 being connected to the second reduction gear 701;

one end of the first lead screw 703 is in transmission connection with the second rotating shaft 702;

the first sliding block 704 is arranged on the first lead screw 703, and the main clamp die 4 is connected with the first sliding block 704. In this embodiment, the output shaft of the first clamping motor 7 drives the first lead screw 703 to rotate after being decelerated by the second speed reducer 701, so that the first sliding block 704 slides on the first lead screw 703, and the first sliding block 704 drives the main clamping mold 4 to contract, so that the main clamping mold 4 clamps or releases the pipe bending mold 3.

Further, as a preferred embodiment, the device further comprises a first gear 705 and a second gear 706, the first gear 705 is connected with the rotating shaft, the second gear 706 is connected with one end of the first lead screw 703, and the first gear 705 is meshed with the second gear 706. In this embodiment, the rotation shaft of the main clamp module 17 is connected to the rotation shaft by a gear transmission manner, or may be connected by a belt transmission manner of the guide clamp module.

Further, as a preferred embodiment, the first clamp motor 7 and the second reduction gear 701 are provided at the upper end of the mount 2, and the second rotation shaft 702, the first lead screw 703, and the first slider 704 are respectively located at the lower end of the mount 2. In this embodiment, as shown in fig. 1, the first clamping motor 7 is located at the upper end of the second speed reducer 701, and the second speed reducer 701 is connected and fixed to the mounting base 2.

Further, as a preferred embodiment, the guiding and clamping module includes a second clamping motor 8, a third speed reducer 801, a third rotating shaft 802, a first belt pulley 803, a second belt pulley 804, a belt 805, a second lead screw 806 and a second slider 807, the second clamping motor 8 is connected to the third speed reducer 801, the second clamping motor 8 and the third speed reducer 801 are both disposed at the upper end of the mounting base 2, the third rotating shaft 802 is disposed at the lower end of the mounting base 2, one end of the third rotating shaft 802 is connected to the third speed reducer 801, the third rotating shaft 802 is provided with the first belt pulley 803, the second lead screw 806 is provided with the second belt pulley 804, the belt 805 is connected to the first belt pulley 803 and the second belt pulley 804, the second lead screw 806 is provided with the second slider 807, and the second slider 807 is connected to the guiding and clamping module 5. In this embodiment, the third rotating shaft 802 of the second clamping motor 8 rotates, the third rotating shaft 802 drives the first belt pulley 803 to rotate, the first belt pulley 803 drives the second belt pulley 804 to rotate through the belt 805, so that the second belt pulley 804 drives the second lead screw 806 to rotate, and the second slider 807 slides along the axial direction of the second lead screw 806 under the rotation of the second lead screw 806, thereby controlling the guide clamp mold 5 to clamp or loosen the bending mold 3. In this embodiment, the third rotating shaft 802 and the second lead screw 806 are connected by a belt transmission, or may be connected by a gear transmission in the main clamp module 17.

Further, as a preferred embodiment, the robot connecting device further comprises a robot connecting flange 9, the robot connecting flange 9 is arranged on one side of the mounting base 2, and the robot connecting flange 9 is used for connecting the mounting base 2 and the robot.

Further, as a preferred embodiment, the guiding and clamping follow-up module comprises a driving motor 10 arranged at the lower end of the mounting base 2, and the driving motor 10 is used for driving the guiding and clamping die 5 to move along the X direction. The pipe bending motor 6, the first clamping motor 7, the second clamping motor 8 and the driving motor 10 in the embodiment all adopt servo motors, all the servo motors are directly controlled by the robot demonstrator, and the driving motor 10 can also adopt an air cylinder or an oil cylinder to replace. In this embodiment, the first clamping motor 7 and the second clamping motor 8 can both rotate forward and backward, so as to slide the first slider 704 and the second slider 807 back and forth. The bending die 3 in this embodiment is a multi-layer die, and here, a double-layer die is adopted, which corresponds to different pipes and different bending radii, respectively, as shown in fig. 5. In the pipe bending process, the pipe bending die 3 rotates, and the driving motor 10 drives the guide clamp die 5 to move along the X direction. After the pipe bending is finished, the driving motor 10 drives the guide clamp mould 5 to return to the original position. The driving motor 10 in this embodiment may be driven by replacing it with an air cylinder or an oil cylinder.

The process of bending the pipe comprises the following steps:

the method comprises the following steps: the robot (pipe bending robot 14) holds the full-servo robot pipe bender 1, and the first clamping motor 7 in the robot control main clamping module 17 controls the main clamping die 4 to clamp the pipe fitting, so that the pipe fitting is grabbed. And the tubular is placed in the rotary gripper 16.

Step two: the robot controls a first clamping motor 7 in a main clamping module 17 to drive a main clamping die 4 to loosen, controls a second clamping motor 8 in the guide clamping module to drive a guide clamping die 5 to clamp a pipe fitting, does not need to completely clamp the pipe fitting at the moment, enables the pipe fitting to be in a half-clamping state, and can rotate and move in a pipe bending die 3.

Step three: the robot holds the full-servo robot pipe bender 1 by hand and moves to a first bending point of a pipe fitting, the robot controls the main clamping mold 4 to clamp the pipe bending mold 3, the guide clamping mold 5 clamps the pipe bending mold 3, and the pipe fitting is clamped completely at the moment. The robot controls the pipe bending motor 6 to enable the main clamping module 17 and the pipe bending die 3 to integrally rotate, and meanwhile, the robot controls the driving motor 10 to enable the guide clamping die 5 to move along the X direction, so that the pipe fitting is bent to a required angle.

Step four: the robot controls the second clamping motor 8 to loosen the guide clamping mould 5, enables the guide clamping mould 5 to return to the original position, and controls the first clamping motor 7 to loosen the main clamping mould 4. At this time, the pipe bender loosens the pipe fitting, and the robot controls the pipe bending motor 6 to return the main clamping module 17 to the zero position.

Step five: and (4) moving the robot hand-held full-servo robot pipe bender 1 to the next bending point position of the pipe fitting, and repeating the third step and the fourth step to finish the bending of other bending points of the pipe fitting. After the pipe bending is finished, the pipe bending motor 6 returns to the zero position, the first clamping motor 7 drives the main clamping mold 4 to clamp tightly, and the second clamping motor 8 drives the guide clamping mold 5 to clamp tightly. The rotary clamp 16 is loosened, the robot clamps the pipe fittings for blanking, and the pipe fittings are grabbed to the blanking frame 15 after the pipe bending is completed.

The above description is only a preferred embodiment of the present application, and does not limit the scope and the embodiments of the present application.

The present application further includes, on the basis of the above preferred embodiment, the following implementation modes:

as shown in fig. 6, fig. 6 is a schematic diagram of a robot automatic pipe bending workstation, the robot automatic pipe bending workstation includes a base 11 and a control cabinet 12 disposed on the base 11, an automatic feeding machine 13 is disposed on one side of the control cabinet 12, a pipe bending robot 14 is disposed on one side of the automatic feeding machine 13, a full servo robot pipe bender 1 is disposed on an arm of the pipe bending robot 14, a blanking rack 15 is disposed on one side of the pipe bending robot 14 away from the automatic feeding machine 13, and a rotary gripper 16 is further disposed on one side of the pipe bending robot 14. The control cabinet 12 in this embodiment is used to control the automatic feeder 13, and the full servo robot bender 1.

As shown in fig. 7, fig. 7 shows a scenario where the full servo robot bender is applied to a robot. The pipe bending machine comprises a pipe bending robot 14, a full-servo robot pipe bending machine 1, a rotary clamp 16, a pipe fitting auxiliary supporting mechanism 18, a pipe fitting auxiliary supporting mechanism cabinet 19 and a robot guide rail 20, wherein the pipe bending robot 14 is arranged on the robot guide rail 20 and can slide on the robot guide rail 20, the full-servo robot pipe bending machine 1 is arranged on a mechanical arm of the pipe bending robot 14, two pipe fitting auxiliary supporting mechanism cabinets 19 are arranged on one side of the robot guide rail 20 along the length direction of the robot guide rail 20, one end of each pipe fitting auxiliary supporting mechanism cabinet 19 is respectively provided with one pipe fitting auxiliary supporting mechanism 18, and the rotary clamp 16 is arranged between the two pipe fitting auxiliary supporting mechanism cabinets 19. The pipe auxiliary support mechanism cabinet 19 is used to control the pipe auxiliary support mechanism 18. While the tubular auxiliary support mechanism 18 is used to support the tubular and the rotary gripper 16 is used to grip the tubular.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.