阅读说明：本技术 一种便于调整角度的双工位换模台车 (Double-station die changing trolley convenient for angle adjustment ) 是由 范磊 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种便于调整角度的双工位换模台车,包括移动车体,所述移动车体的上表面通过旋转机构转动连接有工作平台,所述工作平台上表面的左右两侧设置有第一工位和第二工位,所述第一工位包括滚轮机构、定位机构和推拉机构,所述滚轮机构设置在工作平台的上表面,所述推拉机构沿着工作平台的竖向设置,本发明在工作平台上设置第一工位和第二工位,换模时第三电机带动丝杆旋转,丝杆在旋转的过程中能够带动安装块在长槽内移动,安装块在移动的过程中能够带动挂钩组件移动,通过挂钩组件与模具牢牢地扣在一起,将更换的模具拉出到第二工位,通过第一工位放入新模具,从而提高了换模台车的工作效率。(The invention discloses a double-station die change trolley convenient for angle adjustment, which comprises a movable trolley body, wherein the upper surface of the movable trolley body is rotatably connected with a working platform through a rotating mechanism, the left side and the right side of the upper surface of the working platform are provided with a first station and a second station, the first station comprises a roller mechanism, a positioning mechanism and a push-pull mechanism, the roller mechanism is arranged on the upper surface of the working platform, and the push-pull mechanism is arranged along the vertical direction of the working platform. Thereby improving the working efficiency of the die change trolley.)

1. The double-station die changing trolley convenient for angle adjustment is characterized by comprising a moving trolley body (1), wherein the upper surface of the moving trolley body (1) is rotatably connected with a working platform (3) through a rotating mechanism (2), a first station (4) and a second station (5) are arranged on the left side and the right side of the upper surface of the working platform (3), the first station (4) comprises a roller mechanism (6), a positioning mechanism (7) and a push-pull mechanism (8), the roller mechanism (6) is arranged on the upper surface of the working platform (3) and used for being in contact with a die and helping the die to slide, so that the friction force between the die and the working platform (3) is reduced, the push-pull mechanism (8) is arranged along the vertical direction of the working platform (3) and used for being fixed with the die and driving the die to be dragged and pulled onto the working platform (3) so as to finish the die taking-out work, the positioning mechanisms (7) are located on the left side and the right side of the push-pull mechanism (8) and used for clamping the mold on the first station (4) or the second station (5) to achieve automatic centering, the mold is prevented from being excessively deviated and damaged when moving, and the first station (4) and the second station (5) are identical in structure.

2. The double-station die change trolley convenient for angle adjustment according to claim 1, characterized in that: rotary mechanism (2) include mounting groove (201), bearing (202), ring gear (203) and first motor (204), the upper surface at removal automobile body (1) is seted up in mounting groove (201), one side of bearing (202) and the last fixed surface who removes automobile body (1) are connected, the opposite side of bearing (202) and the lower fixed surface of work platform (3) are connected, the lower fixed surface of first motor (204) is connected at the inner diapire of mounting groove (201), the output fixedly connected with pivot (205) of first motor (204), the one end fixedly connected with driving gear (206) of first motor (204) are kept away from in pivot (205), driving gear (206) are connected with ring gear (203) meshing, the upper surface of ring gear (203) and the lower fixed surface of work platform (3) are connected.

3. The double-station die change trolley convenient for angle adjustment according to claim 1, characterized in that: a fixing plate (9) is arranged between the first station (4) and the second station (5), and the lower surface of the fixing plate (9) is fixed to the upper surface of the working platform (3).

4. The double-station die change trolley convenient for angle adjustment according to claim 1, characterized in that: roller mechanism (6) include round bar (601) and gyro wheel (602), a plurality of recesses (603) have been seted up to the upper surface of work platform (3), both ends rotate with the left and right sides inner wall of recess (603) respectively about round bar (601) and are connected, gyro wheel (602) fixed connection is at the surface of round bar (601), the upper surface of gyro wheel (602) exceeds the upper surface of work platform (3).

5. The double-station die change trolley convenient for angle adjustment according to claim 1, characterized in that: the positioning mechanism (7) comprises a second motor (701), a rotating shaft (702) and two positioning plates (703), a placing groove (704) is arranged on the upper surface of the working platform (3), a movable block (705) is fixedly connected to the middle part of the lower surface of the positioning plate (703), the movable block (705) is positioned in the placing groove (704), the positioning plate (703) is connected with the working platform (3) in a sliding way, the second motor (701) is fixedly connected with the working platform (3), one end of the rotating shaft (702) is fixedly connected with the output end of the second motor (701), the other end of the rotating shaft (702) sequentially penetrates through the two movable blocks (705) and is rotationally connected with the inner wall of the placing groove (704), the left end and the right end of the outer surface of the rotating shaft (702) are respectively provided with a left-handed thread and a right-handed thread, and the rotating shaft (702) is in threaded connection with the movable block (705).

6. The double-station die change trolley convenient for angle adjustment according to claim 5, characterized in that: the front side and the rear side of the lower surface of the positioning plate (703) are fixedly connected with sliding blocks (706), the upper surface of the working platform (3) is provided with a sliding groove (707), and the sliding groove (707) is matched with the sliding blocks (706).

7. The double-station die change trolley convenient for angle adjustment according to claim 1, characterized in that: the push-pull mechanism (8) comprises a third motor (801), a screw rod (802), an installation block (803) and a hook assembly (804), wherein an elongated slot (805) is formed in the upper surface of the working platform (3), the installation block (803) is connected in the elongated slot (805) in a sliding mode, the third motor (801) is fixedly connected to the front side of the working platform (3), one end of the screw rod (802) is fixedly connected with the output end of the third motor (801), the other end of the screw rod (802) penetrates through the installation block (803) and is rotatably connected with the inner wall of the back side of the elongated slot (805), the screw rod (802) is in threaded connection with the installation block (803), and the hook assembly (804) is fixedly connected to the upper surface of the installation block (803).

8. The double-station die change trolley convenient for angle adjustment according to claim 7, characterized in that: the left side and the right side of the mounting block (803) are fixedly connected with guide blocks (806), the inner walls of the left side and the right side of the long groove (805) are provided with guide grooves (807), and the guide blocks (806) are matched with the guide grooves (807).

9. The double-station die change trolley convenient for angle adjustment according to claim 7, characterized in that: couple subassembly (804) includes diaphragm (810), couple main part (811), spring (812), L shaped plate (813) and electric putter (814), the lower surface of diaphragm (810) and the last fixed surface of installation piece (803) are connected, couple main part (811) rotate through round pin axle (815) and connect on diaphragm (810), the back of couple main part (811) is circular arc structure, the one end of spring (812) and the last fixed surface of diaphragm (810) are connected, the other end of spring (812) and the lower fixed surface of couple main part (811) are connected, the bottom of L shaped plate (813) and the last fixed surface of diaphragm (810) are connected, the top and the L shaped plate (813) fixed connection of electric putter (814), electric putter (814) are located the right side top of couple main part (811).

10. The double-station die-changing trolley convenient for angle adjustment according to claim 9, wherein: the telescopic end of the electric push rod (814) is fixedly connected with a U-shaped plate (816), and a rotating wheel (817) is rotatably connected in the U-shaped plate (816).

Technical Field

The invention relates to the technical field of die change trolleys, in particular to a double-station die change trolley convenient for angle adjustment.

Background

The mold is a mold or a tool for obtaining various required products by injection molding, blow molding, extrusion, die casting or forging molding, smelting, stamping and the like, is the core of modern manufacturing industry, and is widely applied to modern factories due to the aspect of production and manufacturing. The mould has the characteristics of large volume and heavy mass due to the stability requirement, so that the position of the mould is difficult to move easily. But the current machining factory generally does not only process one or more products, but manufactures or provides a mould for processing production according to the requirement of a customer. Since few customer orders require a machining plant to perform manufacturing for several months, frequent mold changes are often required to produce for different customers.

When the mould needs to be changed in the completion of the production of current mould, need stop production facility, the mould is changed again in the manual work of taking off, when needs installation mould or removal mould, this work often is more difficult, need use a plurality of manual works and cooperate corresponding moving tool, wastes time and energy, perhaps adopts modes such as overhead traveling crane hoist and mount, fork truck transport and manual lift platform, seriously influences production efficiency, makes the extension of delivery cycle.

Disclosure of Invention

The invention aims to provide a double-station die changing trolley convenient for angle adjustment so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme:

a double-station die changing trolley convenient for angle adjustment comprises a moving trolley body, wherein the upper surface of the moving trolley body is rotatably connected with a working platform through a rotating mechanism, the left side and the right side of the upper surface of the working platform are provided with a first station and a second station, the first station comprises a roller mechanism, a positioning mechanism and a push-pull mechanism, the roller mechanism is arranged on the upper surface of the working platform and used for being in contact with a die and helping the die slide, so that the friction force between the die and the working platform is reduced, the push-pull mechanism is arranged along the vertical direction of the working platform and used for being fixed with the die and driving the die to drag onto the working platform, so that the die is taken out, the positioning mechanism is arranged on the left side and the right side of the push-pull mechanism and used for clamping the die on the first station or the second station to realize automatic centering and avoid the die from being damaged when the die is excessively deviated during moving, the first station and the second station have the same structure.

Preferably, rotary mechanism includes mounting groove, bearing, ring gear and first motor, the upper surface at the removal automobile body is seted up to the mounting groove, one side of bearing and the last fixed surface who removes the automobile body are connected, the opposite side of bearing and work platform's lower fixed surface are connected, the lower fixed surface of first motor is connected at the inner diapire of mounting groove, the output fixedly connected with pivot of first motor, the one end fixedly connected with driving gear of first motor is kept away from in the pivot, the driving gear is connected with the ring gear meshing, the upper surface of ring gear and work platform's lower fixed surface are connected.

Preferably, a fixing plate is arranged between the first station and the second station, and the lower surface of the fixing plate is fixed with the upper surface of the working platform.

Preferably, roller mechanism includes round bar and gyro wheel, a plurality of recesses have been seted up to work platform's upper surface, both ends rotate with the left and right sides inner wall of recess respectively about the round bar to be connected, gyro wheel fixed connection is at the surface of round bar, the upper surface of gyro wheel exceeds work platform's upper surface.

Preferably, positioning mechanism includes second motor, pivot and two locating plates, work platform's upper surface begins to have the standing groove, the lower surface middle part fixedly connected with movable block of locating plate, the movable block is located the standing groove, locating plate and work platform sliding connection, second motor and work platform fixed connection, the one end of pivot and the output fixed connection of second motor, the other end of pivot run through two movable blocks in proper order and be connected with the inner wall rotation of standing groove, left-handed thread and right-handed thread have been seted up respectively at both ends about the pivot surface, pivot and movable block threaded connection.

Preferably, the front side and the rear side of the lower surface of the positioning plate are fixedly connected with sliding blocks, the upper surface of the working platform is provided with a sliding groove, and the sliding groove is matched with the sliding blocks.

Preferably, the push-pull mechanism comprises a third motor, a screw rod, an installation block and a hook assembly, an elongated slot is formed in the upper surface of the working platform, the installation block is connected in the elongated slot in a sliding mode, the third motor is fixedly connected to the front side of the working platform, one end of the screw rod is fixedly connected with the output end of the third motor, the other end of the screw rod penetrates through the installation block and is rotatably connected with the inner wall of the back side of the elongated slot, the screw rod is in threaded connection with the installation block, and the hook assembly is fixedly connected to the upper surface of the installation block.

Preferably, the left side and the right side of the mounting block are both fixedly connected with guide blocks, the inner walls of the left side and the right side of the elongated slot are both provided with guide grooves, and the guide blocks are matched with the guide grooves.

Preferably, the couple subassembly includes diaphragm, couple main part, spring, L shaped plate and electric putter, the lower surface of diaphragm and the last fixed surface of installation piece are connected, the couple main part rotates through the round pin axle and connects on the diaphragm, the back of couple main part is the circular arc structure, the one end of spring and the last fixed surface of diaphragm are connected, the other end of spring and the lower fixed surface of couple main part are connected, the bottom of L shaped plate and the last fixed surface of diaphragm are connected, electric putter's top and L shaped plate fixed connection, electric putter is located the right side top of couple main part.

Preferably, the telescopic end of the electric push rod is fixedly connected with a U-shaped plate, and a rotating wheel is rotatably connected in the U-shaped plate.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the die changing trolley, the first motor drives the connecting shaft to rotate, the connecting shaft can drive the driving gear to rotate in the rotating process, the driving gear can drive the gear ring to rotate in the rotating process, and the gear ring can drive the working platform to rotate in the rotating process, so that the working platform rotates by a certain angle, the first station or the second station is aligned with processing equipment, and the die changing trolley can conveniently work;

2. the rotating shaft is driven to rotate by the second motor, the two movable blocks can be driven to approach each other in the rotating process of the rotating shaft, the positioning plates can be driven to move by the movable blocks in the moving process, the dies on the first station or the second station are clamped by the two positioning plates to realize automatic centering, and the dies are prevented from being excessively deviated and damaged in the moving process;

3. according to the invention, the first station and the second station are arranged on the working platform, the third motor drives the screw rod to rotate during die change, the screw rod can drive the mounting block to move in the long groove during rotation, the mounting block can drive the hook assembly to move during movement, the hook assembly is firmly buckled with the die, the replaced die is pulled out to the second station, and a new die is placed in the die through the first station, so that the working efficiency of the die change trolley is improved.

Drawings

FIG. 1 is a schematic perspective view of the present invention;

FIG. 2 is a schematic structural diagram of a work platform according to the present invention;

FIG. 3 is a schematic structural view of the rotating mechanism of the present invention;

FIG. 4 is a schematic structural view of the push-pull mechanism of the present invention;

FIG. 5 is an enlarged view of the structure at A in FIG. 3 according to the present invention;

FIG. 6 is a schematic view of a positioning plate according to the present invention;

FIG. 7 is a schematic view of the hook assembly of the present invention.

In the figure: 1-moving the vehicle body; 2-a rotating mechanism; 3-a working platform; 4-a first station; 5-a second station; 6-a roller mechanism; 7-a positioning mechanism; 8, a push-pull mechanism; 9-fixing the plate; 201-mounting grooves; 202-a bearing; 203-gear ring; 204-a first motor; 205-a connecting shaft; 206-a drive gear; 601-round bar; 602-a roller; 603-grooves; 701-a second motor; 702-a rotating shaft; 703-positioning plate; 704-a placement slot; 705-active block; 706-a slider; 707-a chute; 801-a third electric machine; 802-lead screw; 803-mounting block; 804-a hook component; 805-elongated slots; 806-a guide block; 807-a guide groove; 810-a transverse plate; 811-hook body; 812-a spring; 813-L shaped plate; 814-an electric push rod; 815-a pin roll; 816-U-shaped plates; 817-rotating wheel.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.

Referring to fig. 1-7, a double-station die-changing trolley convenient for angle adjustment in the figures includes a moving trolley body 1, the upper surface of the moving trolley body 1 is rotatably connected with a working platform 3 through a rotating mechanism 2, a first station 4 and a second station 5 are arranged on the left and right sides of the upper surface of the working platform 3, the first station 4 includes a roller mechanism 6, a positioning mechanism 7 and a push-pull mechanism 8, the roller mechanism 6 is arranged on the upper surface of the working platform 3 and is used for contacting with a die to help the die to slide, so as to reduce the friction between the die and the working platform 3, the push-pull mechanism 8 is arranged along the vertical direction of the working platform 3 and is used for fixing with the die to drive the die to be dragged onto the working platform 3, so as to complete the taking-out work of the die, the positioning mechanism 7 is arranged on the left and right sides of the push-pull mechanism 8 and is used for clamping the die on the first station 4 or the second station 5 to realize automatic centering, the mould is prevented from being excessively deviated and damaged during movement, and the first station 4 and the second station 5 are identical in structure.

Wherein, the rotating mechanism 2 comprises a mounting groove 201, a bearing 202, a gear ring 203 and a first motor 204, the mounting groove 201 is arranged on the upper surface of the moving vehicle body 1, one side of the bearing 202 is fixedly connected with the upper surface of the moving vehicle body 1, the other side of the bearing 202 is fixedly connected with the lower surface of the working platform 3, the lower surface of the first motor 204 is fixedly connected with the inner bottom wall of the mounting groove 201, the output end of the first motor 204 is fixedly connected with a connecting shaft 205, one end of the connecting shaft 205 far away from the first motor 204 is fixedly connected with a driving gear 206, the driving gear 206 is meshed and connected with the gear ring 203, the upper surface of the gear ring 203 is fixedly connected with the lower surface of the working platform 3, the first motor 204 is opened to drive the connecting shaft 205 to rotate, the connecting shaft 205 can drive the driving gear 206 to rotate in the rotating process, the driving gear 206 can drive the gear ring 203 to rotate in the rotating process, the gear ring 203 can drive the working platform 3 to rotate in the rotating process, so that the working platform 3 rotates a certain angle and the second station 5 is aligned with the processing equipment;

meanwhile, a fixing plate 9 is arranged between the first station 4 and the second station 5, the lower surface of the fixing plate 9 is fixed with the upper surface of the working platform 3, and the fixing plate 9 is arranged to facilitate the installation of the first station 4 and the second station 5;

the roller mechanism 6 comprises a round rod 601 and a roller 602, the upper surface of the working platform 3 is provided with a plurality of grooves 603, the left end and the right end of the round rod 601 are respectively rotatably connected with the inner walls of the left side and the right side of the grooves 603, the roller 602 is fixedly connected with the outer surface of the round rod 601, the upper surface of the roller 602 is higher than the upper surface of the working platform 3, and when a mold is dragged onto the working platform 3 from machining equipment, the friction force between the mold and the working platform 3 is reduced by contact with the roller 602;

meanwhile, the positioning mechanism 7 comprises a second motor 701, a rotating shaft 702 and two positioning plates 703, a placing groove 704 is formed on the upper surface of the working platform 3, a movable block 705 is fixedly connected to the middle of the lower surface of the positioning plate 703, the movable block 705 is positioned in the placing groove 704, the positioning plate 703 is connected with the working platform 3 in a sliding manner, the second motor 701 is fixedly connected with the working platform 3, one end of the rotating shaft 702 is fixedly connected with the output end of the second motor 701, the other end of the rotating shaft 702 sequentially penetrates through the two movable blocks 705 and is rotatably connected with the inner wall of the placing groove 704, left-handed threads and right-handed threads are respectively formed at the left end and the right end of the outer surface of the rotating shaft 702, the rotating shaft 702 is in threaded connection with the movable blocks 705, the second motor 701 is turned on to drive the rotating shaft 702 to rotate, the rotating shaft 702 can drive the two movable blocks 705 to approach each other, and the movable blocks 705 can drive the positioning plate 703 to move in the moving process, the mold on the first station 4 is clamped by the two positioning plates 703 to realize automatic centering;

in addition, the front side and the rear side of the lower surface of the positioning plate 703 are fixedly connected with sliding blocks 706, the upper surface of the working platform 3 is provided with a sliding groove 707, the sliding groove 707 is matched with the sliding block 706, the positioning plate 703 is more stably moved by matching the sliding block 706 with the sliding groove 707, and the phenomenon that the positioning plate 703 is inclined and clamped is avoided;

meanwhile, the push-pull mechanism 8 comprises a third motor 801, a screw rod 802, an installation block 803 and a hook assembly 804, an elongated slot 805 is formed in the upper surface of the working platform 3, the installation block 803 is slidably connected in the elongated slot 805, the third motor 801 is fixedly connected to the front surface of the working platform 3, one end of the screw rod 802 is fixedly connected with the output end of the third motor 801, the other end of the screw rod 802 penetrates through the installation block 803 and is rotatably connected with the inner wall of the back surface of the elongated slot 805, the screw rod 802 is in threaded connection with the installation block 803, the hook assembly 804 is fixedly connected to the upper surface of the installation block 803, the third motor 801 is turned on to drive the screw rod 802 to rotate, and the screw rod 802 can drive the installation block 803 to move in the elongated slot 805 in the rotating process;

the left side and the right side of the mounting block 803 are fixedly connected with guide blocks 806, the inner walls of the left side and the right side of the long groove 805 are provided with guide grooves 807, the guide blocks 806 are matched with the guide grooves 807, and the guide blocks 806 are matched with the guide grooves 807 to enable the mounting block 803 to move more stably, so that the mounting block 803 is prevented from rotating along with the screw rod 802;

wherein, the hook component 804 comprises a horizontal plate 810, a hook body 811, a spring 812, an L-shaped plate 813 and an electric push rod 814, the lower surface of the horizontal plate 810 is fixedly connected with the upper surface of the mounting block 803, the hook body 811 is rotatably connected on the horizontal plate 810 through a pin 815, the back of the hook body 811 is in an arc structure, one end of the spring 812 is fixedly connected with the upper surface of the horizontal plate 810, the other end of the spring 812 is fixedly connected with the lower surface of the hook body 811, the bottom end of the L-shaped plate 813 is fixedly connected with the upper surface of the horizontal plate 810, the top end of the electric push rod 814 is fixedly connected with the L-shaped plate 813, the electric push rod 814 is positioned above the right side of the hook body 811, the mounting block 803 can drive the horizontal plate 810 to move in the moving process, the horizontal plate 810 can drive the hook body 811 to move in the moving process, because the back of the hook body 811 is in an arc structure, the hook body 811 is in contact with the hanging rod on the mold, the hook main body 811 rotates around the pin 815 and stretches the spring 812, and after the hook main body 811 moves to a position, the hook main body 811 resets through the restoring force of the spring 812 and is firmly buckled with the mold, so that falling off when the mold is moved is avoided;

meanwhile, a U-shaped plate 816 is fixedly connected to the telescopic end of the electric push rod 814, a rotating wheel 817 is rotatably connected to the U-shaped plate 816, the rotating wheel 817 is driven to move by the extension of the electric push rod 814, and at the moment, the rotating wheel 817 is in contact with the hook main body 811 to rotate around the pin 815 against the pulling force of the spring 812, so that the hook main body 811 is separated from the mold.

Principle of retooling platform truck: the movable car body 1 is driven to the side of equipment needing to replace a mould, then the first motor 204 is opened to drive the connecting shaft 205 to rotate, the connecting shaft 205 can drive the driving gear 206 to rotate in the rotating process, the driving gear 206 can drive the gear ring 203 to rotate in the rotating process, the gear ring 203 can drive the working platform 3 to rotate in the rotating process, so that the working platform 3 can rotate for a certain angle, the second station 5 is aligned with processing equipment, then the third motor 801 is opened to drive the screw rod 802 to rotate, the screw rod 802 can drive the mounting block 803 to move in the long groove 805 in the rotating process, the mounting block 803 is more stable to move due to the matching of the guide block 806 and the guide groove 807, the mounting block 803 is prevented from rotating along with the screw rod 802, the mounting block 803 can drive the transverse plate 810 to move in the moving process, and the transverse plate 810 can drive the hook body 811 to move in the moving process, because the back of the hook body 811 is in a circular arc structure, the hook body 811 is contacted with a hanging rod on a mold at the moment, so that the hook body 811 rotates around a pin 815 and stretches a spring 812, when the hook body 811 moves to the position, the hook body 811 is reset by restoring force of the spring 812 and firmly buckled with the mold to avoid falling off when the mold is moved, then the third motor 801 is reversed to enable the mold to be dragged to a working platform 3 from a processing device, friction between the mold and the working platform 3 is reduced by contacting with a roller 602, so that the mold is taken out, then the second motor 701 is opened to drive the rotating shaft 702 to rotate, the rotating shaft 702 can drive two movable blocks 705 to approach each other in the rotating process, the movable blocks 705 can drive the positioning plate 703 to move in the moving process, and the mold on the first station 4 is clamped by the two positioning plates 703 to realize automatic centering, and finally, moving the vehicle body 1 to replace the new mold on the first station 4.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.